THE VIBRATIONAL SPECTRUM OF A POLYATOMIC MOLECULE (Revised 4/7/2004)

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "THE VIBRATIONAL SPECTRUM OF A POLYATOMIC MOLECULE (Revised 4/7/2004)"

Transcription

1 INTRODUCTION THE VIBRATIONAL SPECTRUM OF A POLYATOMIC MOLECULE (Revised 4/7/2004) The vibrational motion of a molecule is quantized and the resulting energy level spacings give rise to transitions in the mid-ir portion of the electromagnetic spectrum (4000 to ca. 400 cm -1 ). As you know from study of the diatomic harmonic oscillator, the energies (or wavenumber positions, cm -1 ) of these transitions are related to the bond strength (force constant), bond length, and atomic masses (reduced mass). In polyatomic spectra, the positions and relative intensities of the vibrational modes depend on the symmetry (i.e. shape or structure) of the molecule, as well as the bond strengths and masses. For this reason, vibrational spectra (IR and Raman) can provide detailed structural information. This analysis, or interpretation, of an infrared spectrum to obtain structural information is the objective of this lab. In this experiment you will obtain an infrared spectrum of a polyatomic molecule, predict its selection rules, assign vibrational modes, and then compare these with the vibrational mode positions and intensities predicted for that molecule using HyperChem. Using group theory, we shall predict the spectral selection rules, i.e. predict the spectra for a particular structural model. Assignment of vibrational modes in a spectrum involves relating the experimental spectrum and the predicted spectrum so that each observed vibrational band is identified as to its theoretical origin. A series of empirical rules is provided below to aid in this assignment. Also, a chart defining the well-known positions of group frequencies will be available. (These charts summarize the vast knowledge obtained from the extensive, experimental spectral database that has been collected, literally, over the past 60 years.) Finally, the results of the HyperChem calculation will be compared with the above. Because these calculated normal mode positions will be harmonic frequencies, they must be multiplied by a constant to relate them to the empirical, anharmonic band positions. This constant depends upon the orbital basis set that you use. BACKGROUND For a non-linear polyatomic molecule containing n atoms, there will be 3n-6 vibrational degrees of freedom (3n-5 for a linear molecule) [1]. This number represents the maximum number of vibrational modes for the molecule. However, often the observed number is less because of degeneracies and selection rules. Because of the symmetry (i.e. structure), some transitions may be degenerate, and some transitions may be forbidden and not observed; others will be allowed and observed. Allowed or forbidden transitions are also referred to as active or inactive vibrational modes, respectively. For an IR absorption to be allowed between two vibrational levels, a change in dipole moment (µ) must occur as the atoms move, and υ must equal ± 1. A fundamental vibrational mode will involve a transition from the υ = 0 level to the υ = 1 level. Group theory is used to predict the characteristic or normal modes of vibration for a molecule. (Normal refers to the fact that these modes of vibration are orthogonal to each other, i.e. independent of each other.) For molecules with many atoms, 3n-6 becomes very large, and this

2 can result in a seemingly complex IR spectral pattern. However, the presence of symmetry in a molecule often simplifies the vibrational spectrum. Recognition of this symmetry simplifies and allows the interpretation of even complex vibrational spectra, both IR and Raman. The predicted symmetry species define the activity of each (allowed or forbidden) vibrational mode in the IR and in the Raman spectra, and these are referred to as selection rules. Also, the stretching modes can be predicted to distinguish them from the bending and torsional vibrations. The atom masses and force constants determine the precise region of the spectrum at which each normal mode vibrates, i.e., the energy (or frequency or wavenumber) for each. The general region in which various species will absorb can be obtained from group frequency charts, which summarize empirical information. Vibrational transitions may also be observed using Raman spectroscopy. The selection rules for IR and for Raman spectra differ so that the two techniques provide complementary information, not redundant information. Therefore, the Raman spectrum provides significant new structural information, in addition to that provided by the IR spectrum. To be Raman active (i.e. allowed), there must be a change in polarizability (α ij ) during the vibration. This can be better understood as a changing induced dipole. Empirical Rules Used to Interpret Spectra When we interpret a spectrum, we shall relate (or assign) each band in the spectrum to its origin as predicted by the group theoretical selection rules. The following empirical rules are used in this assignment process for molecular species. The band position (cm -1 ) provides information about the type of vibration. Vibrational modes can be of three basic types, stretching modes (ν), bending modes (δ) or torsional modes (τ). Stretching modes of vibration occur at higher energy, i.e. higher wavenumber, than bending modes. Torsional modes appear at even lower energy. Both the type of vibration and the symmetry species of each vibrational mode influence the relative band intensities. The intensities of asymmetric stretching modes will be greater than asymmetric bending (or torsional) modes in the IR. If one compares asymmetric species with symmetric species of each type (stretch or bend), the asymmetric species will, in general, be stronger in the IR spectrum. (For a Raman spectrum, the opposite is true; the symmetric species are stronger.) The spectra, both the IR and Raman, will contain some weak bands that are fundamental vibrations and some weak bands that are overtone or combination bands. (Overtone and combination bands are not allowed, and therefore exhibit reduced intensities.) To distinguish the two, compare the IR and Raman spectra. If a band is weak in both the IR and the Raman, it is more likely to be an overtone. A fundamental is expected to be strong in one and weak in the other. However, it is possible, on occasion, to have a mode be weak in both. When comparing IR and Raman band positions, how do you decide if the bands may be ascribed to the "same" vibrational mode, i.e. that these are coincident in the IR and the Raman? This is defined by the experimental error in each spectrum. The maximum precision (for a sharp band) is defined by the spectral resolution used for the scan. For example, if you used 2 cm -1 resolution, then your precision (or uncertainty) is ±2 cm -1. For the Raman spectrum, assume 2-3 cm -1 for a sharp peak. For broad bands in either spectrum, the precision will be less; assume ± 3-

3 4 cm -1 for this lab experiment. The criterion for coincidence is then the sum of the two uncertainties. Group Theoretical Analysis The first point group that you use to predict the IR and Raman spectral selection rules should be the ideal structure, the highest symmetry point group possible. Sometimes, more than one structure (and point group) is possible. Do the group theoretical calculation for both and determine which applies to the real spectrum. For example, when calculating the minimum energy geometry, you may find that this geometry has lower symmetry than the ideal and belongs to a lower symmetry point group. You will then need to predict the IR and Raman selection rules for this point group. When comparing the two sets of predictions with the experimental data, you may then decide which agrees better with the experimental results. There are two "background" pages that will be given to you as handouts in class. These are a) How is Group Theory Used? and b) Applying Group Theory: Representations of Vibrational Motion. Copies of these follow this experiment for your convenient reference. HyperChem Output, Anharmonicity Correction, Negative Frequencies, and Degeneracy HyperChem calculates all of the fundamental modes, both IR and Raman, as well as the IR intensities. Thus it outputs two spectra, one with all of the bands plotted, and the second with just the IR active modes. Since it does not calculate Raman intensities, it cannot plot a Raman spectrum. HyperChem also identifies the symmetry species of each mode. Since you know the IR and Raman activity from your group theoretical calculations, you can identify the Raman activity of each mode yourself. You can predict the approximate Raman intensities from the group theoretical predictions (the totally symmetric species will be stronger in the Raman). The frequencies calculated using HyperChem (or any other ab initio calculation) are harmonic frequencies. To correct for anharmonicity the calculated, harmonic frequencies are multiplied by a constant. This constant depends upon the basis set used. Professor Brown recommends use of the HF/6-13G* basis set (select the 6-13G* basis in the setup) to minimize the energy and to calculate the geometry. Multiply your calculated values by if you use the 6-13G* basis set [2]. This correction will allow you to compare your experimental values with your calculated values. Be sure to place this information in a table and discuss it. This correction factor is an empirically determined value which can vary from 0.89 to The precise value needed for each molecule or even for each fundamental vibrational mode may differ slightly. This is especially true for the lower frequency vibrational modes such as bending and torsional modes. After you "assign" each fundamental vibration and compare the experimental and harmonic, calculated values, you can calculate the precise coefficient needed for each mode. (These could be placed in a second table.) The overall average coefficient for your molecule, as well as the average values for just the stretching modes and for just the bending plus torsional modes will be interesting to calculate and discuss in your report. How much do these differ from the literature value reported above (0.8929)?

4 If a negative frequency (an imaginary energy) is obtained, this means that you are on a saddle point. You are not at the minimum energy structure. Go back and recalculate the minimum energy structure. If your molecule exhibits degenerate vibrational modes (E or T species), HyperChem will calculate 2 or 3 essentially identical (i.e. within experimental error) frequencies for doubly or triply degenerate vibrational modes, respectively. ASSIGNED COMPOUNDS GROUP 1a: methyl iodide, CH 3 I GROUP 1b: formamide, HCONH 2 nitromethane, CH 3 NO 2 GROUP 2a: acetonitrile, CH 3 CN GROUP 2b: nitromethane, CH 3 NO 2 formamide, HCONH 2 GROUP 3a: chloroform, CHCl 3 GROUP 3b: methylene chloride, CH 2 Cl 2 EXPERIMENTAL PROCEDURE 1. Obtain an IR spectrum of your group s assigned compound using the Mattson FTIR located in room 601B. (Instructions for it s operation are also available in 601B.) You will need to schedule the IR with the lab supervisor with at least 1 day s notice. Prepare your sample by placing it on an adsorbent polymer sample card (obtained from the lab supervisor). The strongest absorption bands in your IR spectrum should absorb no more than 1 absorbance unit (A 1); at least 10% transmittance (10-15% is better) is required to insure resolution of multiple peaks within very strong peaks. You may want to record and/or report two IR spectra, one that clearly resolves all bands, even the strongest, and a second (more concentrated or thicker), which provides good definition of the weaker bands in the spectrum. 2. Use HyperChem to draw your molecule, calculate the minimum energy configuration, and generate the vibrational energies for your assigned compound. A negative frequency means that you have not obtained the minimum energy configuration. Ideally, the symmetry of this configuration and that used for your group theoretical analysis should be the same; however, the former symmetry may be of lower symmetry. 3. Predict the infrared and Raman spectra for your molecule (using group theory) and assign the observed vibrational modes (i.e. relate the experimental spectra to the group theoretical predictions). Raman spectral data will be provided for each molecule. 4. Submit a group report (see below) that presents the above data and results in tables and figures, and includes a comparison of the group theoretical analysis of the experimental spectra and the vibrational absorptions generated by HyperChem. Evaluate how well the

5 three compare. LABORATORY REPORT FORMAT Although you are experimentally obtaining the IR spectrum yourself, your report will interpret both the IR spectrum and the Raman spectrum. The reason for this is that the two, together, provide more detailed structural information than either by itself. The report should include the following: a) a results section with Figure(s) of your IR spectrum (with the IR spectral band positions written in near each major band). Your Raman spectral data should be included as a Figure (or in a table) as well. b) a Table containing the IR and Raman band positions for your compound and your assignments for each band (these should include ν, δ, or τ, the atoms involved, and the symmetry species). Indicate the intensity of each band in your table by using the following symbols: vs=very strong, s=strong, m=medium, w=weak, vw=very weak c) a concise discussion to explain how you made your band assignments. d) a discussion relating part c (your empirical band positions and assignments) to your calculated frequencies. e) a conclusion as to what the actual structure of your molecule is, based on your data. NOTE: No preliminary report is required for this experiment. Reports submitted by Monday, April 26 th will be proof-read (for style, formatting, grammar, punctuation, etc.) and returned to you. This report must then be re-submitted to the lab s faculty advisor, Professor Cornilsen, for grading. The final report is due no later than Thursday, April 29 th. REFERENCES 1. Ira N. Levine, Physical Chemistry, 5 th edn., McGraw-Hill Co. Inc., N.Y., 2002, pp J. B. Foresman and A. Frisch, Exploring Chemistry with Electronic Structure Methods, 2 nd Edn., Gaussian, Inc., Pittsburgh, PA, 1995, p. 64.

6 Applying Group Theory: Representations of Vibrational Motion April 12, BCC The following is an introduction to the use of group theory. To apply the group theory, we must represent some physical entity that defines the property of interest. For vibrational spectroscopy, we represent the vibrational motion of the molecule in terms of 3 unit Cartesian displacement vectors on each atom. Thus 3n degrees of motion (or degrees-of-freedom) are defined, where n is the number of atoms in the molecule. This is referred to as the basis set. The 3n-6 normal modes of vibration will be combinations of these Cartesian displacement vectors. Six of the 3n degrees of freedom will be rotations (3) and translations (3) of the molecule as a whole. The remaining 3n-6 degrees of freedom represent the normal (i.e. mathematically unique and independent) modes of vibration. After the point group is defined for a molecule, a reducible representation (Γ) is produced by operating on the basis set with each symmetry operation, R. For each atom that is not shifted during the operation (i.e. left invariant) the vectors are summed, with a +1 if the vector is not inverted, and a -1 if the vector is inverted. These sums produce the character for that operation, χ(r). This reducible representation actually represents the chosen basis set, which is the 3n degrees of vibrational freedom in this case. See how this representation and the vibrational selection rules are obtained for a tetrahedral molecule (or tetrahedral ion) in Cotton s text, in a section entitled Tetrahedral Molecules, Such as Methane. * A second method of representing molecular motion is to use internal coordinates (bond lengths, bond angles, or torsional angles) for the basis set. Cotton* also obtains reproducible representations (Γ) for the CH stretches and HCH bends. How these reducible representations are obtained and how the reducible representations are reduced will be discussed in class (and in Levine s text, Chap. 21). * F. A. Cotton, Chemical Applications of Group Theory, 3 rd edn., Wiley, NY, 1990.

7 HOW IS GROUP THEORY USED? April 12, BCC After we learn to classify molecules in terms of their symmetry, i.e. assign a molecule to the appropriate point group, we wish to apply it to specific examples. This general application process is outlined in the following, using vibrational spectroscopy as an example. Other examples are included in parentheses. 1. First, the point group is assigned. 2. Secondly, a basis set is chosen to represent the physical entities that we wish to study, e.g. vibrational modes of a molecule. (Other examples include atomic orbital basis sets to represent and determine hybrid orbitals or molecular orbitals.). For vibrational modes two different basis sets are useful. The first is a Cartesian coordinate basis set, which represents all motions (translation, as well as rotation & vibration about the center-of-mass) of a molecule. The second type of basis set uses internal coordinates, which represent specific inter-atomic motions. In each case our final result will be a group theoretical representation of this basis set which will allow determination of the symmetry of the excited state, vibrational energy levels (and of their corresponding wavefunctions). 3. The symmetry operations of the molecule are applied to the basis set to obtain a reducible representation which represents all of the properties in question. 4. The reducible representation is reduced to form irreducible representations (i.e. it is reduced into "symmetry species") which represent the results of our application. These species represent the excited vibrational states of the molecule, the normal modes of vibration. 5. The irreducible representations (or symmetry species) obtained are then used to determine selection rules for transitions between the energy levels in question, i.e. to predict spectral selection rules for infrared and Raman spectra. The ground state vibrational level is always represented by the totally symmetric symmetry species. (If we represent electronic energy levels or molecular orbitals, selection rules for electronic transitions can be predicted.)

16.1 Molecular Vibrations

16.1 Molecular Vibrations 16.1 Molecular Vibrations molecular degrees of freedom are used to predict the number of vibrational modes vibrations occur as coordinated movement among many nuclei the harmonic oscillator approximation

More information

USING THE OCEAN OPTICS R-2000 RAMAN SPECTROMETER IN THE UNDERGRADUATE LABORATORY

USING THE OCEAN OPTICS R-2000 RAMAN SPECTROMETER IN THE UNDERGRADUATE LABORATORY Proceedings of the South Dakota Academy of Science, Vol. 79 (2000) 63 USING THE OCEAN OPTICS R-2000 RAMAN SPECTROMETER IN THE UNDERGRADUATE LABORATORY Deanna L. Donohoue, Gary W. Earl and Arlen Viste Department

More information

Vibrations of Carbon Dioxide and Carbon Disulfide

Vibrations of Carbon Dioxide and Carbon Disulfide Vibrations of Carbon Dioxide and Carbon Disulfide Purpose Vibration frequencies of CO 2 and CS 2 will be measured by Raman and Infrared spectroscopy. The spectra show effects of normal mode symmetries

More information

V( x) = V( 0) + dv. V( x) = 1 2

V( x) = V( 0) + dv. V( x) = 1 2 Spectroscopy 1: rotational and vibrational spectra The vibrations of diatomic molecules Molecular vibrations Consider a typical potential energy curve for a diatomic molecule. In regions close to R e (at

More information

Spectroscopic Selection Rules

Spectroscopic Selection Rules E 0 v = 0 v = 1 v = 2 v = 4 v = 3 For a vibrational fundamental (Δv = ±1), the transition will have nonzero intensity in either the infrared or Raman spectrum if the appropriate transition moment is nonzero.

More information

Introduction to Molecular Vibrations and Infrared Spectroscopy

Introduction to Molecular Vibrations and Infrared Spectroscopy hemistry 362 Spring 2017 Dr. Jean M. Standard February 15, 2017 Introduction to Molecular Vibrations and Infrared Spectroscopy Vibrational Modes For a molecule with N atoms, the number of vibrational modes

More information

/2Mα 2 α + V n (R)] χ (R) = E υ χ υ (R)

/2Mα 2 α + V n (R)] χ (R) = E υ χ υ (R) Spectroscopy: Engel Chapter 18 XIV 67 Vibrational Spectroscopy (Typically IR and Raman) Born-Oppenheimer approx. separate electron-nuclear Assume elect-nuclear motion separate, full wave fct. ψ (r,r) =

More information

Infrared Spectroscopy: Identification of Unknown Substances

Infrared Spectroscopy: Identification of Unknown Substances Infrared Spectroscopy: Identification of Unknown Substances Suppose a white powder is one of the four following molecules. How can they be differentiated? H N N H H H H Na H H H H H A technique that is

More information

Quote from Eugene Paul Wigner

Quote from Eugene Paul Wigner Quote from Eugene Paul Wigner See also: Current Science, vol. 69, no. 4, 25 August 1995, p. 375 From the preface to his book on group theory: Wigner relates a conversation with von Laue on the use of group

More information

PAPER No. : 8 (PHYSICAL SPECTROSCOPY) MODULE No. : 5 (TRANSITION PROBABILITIES AND TRANSITION DIPOLE MOMENT. OVERVIEW OF SELECTION RULES)

PAPER No. : 8 (PHYSICAL SPECTROSCOPY) MODULE No. : 5 (TRANSITION PROBABILITIES AND TRANSITION DIPOLE MOMENT. OVERVIEW OF SELECTION RULES) Subject Chemistry Paper No and Title Module No and Title Module Tag 8 and Physical Spectroscopy 5 and Transition probabilities and transition dipole moment, Overview of selection rules CHE_P8_M5 TABLE

More information

Lecture 10 Diatomic Vibration Spectra Harmonic Model

Lecture 10 Diatomic Vibration Spectra Harmonic Model Chemistry II: Introduction to Molecular Spectroscopy Prof. Mangala Sunder Department of Chemistry and Biochemistry Indian Institute of Technology, Madras Lecture 10 Diatomic Vibration Spectra Harmonic

More information

Infrared Spectroscopy

Infrared Spectroscopy Infrared Spectroscopy IR Spectroscopy Used to identify organic compounds IR spectroscopy provides a 100% identification if the spectrum is matched. If not, IR at least provides information about the types

More information

Symmetrical: implies the species possesses a number of indistinguishable configurations.

Symmetrical: implies the species possesses a number of indistinguishable configurations. Chapter 3 - Molecular Symmetry Symmetry helps us understand molecular structure, some chemical properties, and characteristics of physical properties (spectroscopy) used with group theory to predict vibrational

More information

Determining the Normal Modes of Vibration

Determining the Normal Modes of Vibration Determining the ormal Modes of Vibration Introduction vibrational modes of ammonia are shown below! 1 A 1 ) symmetric stretch! A 1 ) symmetric bend! 3a E) degenerate stretch Figure 1 Vibrational modes!

More information

INFRARED ABSORPTION SPECTROSCOPY. References: See relevant sections in undergraduate text. Learn from your instructor how to use the spectrometer.

INFRARED ABSORPTION SPECTROSCOPY. References: See relevant sections in undergraduate text. Learn from your instructor how to use the spectrometer. INFRARED ABSORPTION SPECTROSCOPY References: See relevant sections in undergraduate text Background: Learn from your instructor how to use the spectrometer. Know definitions of the following and their

More information

Molecular energy levels and spectroscopy

Molecular energy levels and spectroscopy Molecular energy levels and spectroscopy 1. Translational energy levels The translational energy levels of a molecule are usually taken to be those of a particle in a three-dimensional box: n x E(n x,n

More information

Symmetric Stretch: allows molecule to move through space

Symmetric Stretch: allows molecule to move through space BACKGROUND INFORMATION Infrared Spectroscopy Before introducing the subject of IR spectroscopy, we must first review some aspects of the electromagnetic spectrum. The electromagnetic spectrum is composed

More information

Structure Determination. How to determine what compound that you have? One way to determine compound is to get an elemental analysis

Structure Determination. How to determine what compound that you have? One way to determine compound is to get an elemental analysis Structure Determination How to determine what compound that you have? ne way to determine compound is to get an elemental analysis -basically burn the compound to determine %C, %H, %, etc. from these percentages

More information

Determining the Normal Modes of Vibration

Determining the Normal Modes of Vibration Determining the ormal Modes of Vibration Introduction at the end of last lecture you determined the symmetry and activity of the vibrational modes of ammonia Γ vib 3 ) = A 1 IR, pol) + EIR,depol) the vibrational

More information

IR absorption spectroscopy

IR absorption spectroscopy IR absorption spectroscopy IR spectroscopy - an analytical technique which helps determine molecules structure When a molecule absorbs IR radiation, the vibrational energy of the molecule increase! The

More information

MOLECULAR SPECTROSCOPY

MOLECULAR SPECTROSCOPY MOLECULAR SPECTROSCOPY First Edition Jeanne L. McHale University of Idaho PRENTICE HALL, Upper Saddle River, New Jersey 07458 CONTENTS PREFACE xiii 1 INTRODUCTION AND REVIEW 1 1.1 Historical Perspective

More information

Advanced Physical Chemistry Chemistry 5350 ROTATIONAL AND VIBRATIONAL SPECTROSCOPY

Advanced Physical Chemistry Chemistry 5350 ROTATIONAL AND VIBRATIONAL SPECTROSCOPY Advanced Physical Chemistry Chemistry 5350 ROTATIONAL AND VIBRATIONAL SPECTROSCOPY Professor Angelo R. Rossi http://homepages.uconn.edu/rossi Department of Chemistry, Room CHMT215 The University of Connecuticut

More information

Asymmetry of Peaks in the XPS of Polymers

Asymmetry of Peaks in the XPS of Polymers Asymmetry of Peaks in the XPS of Polymers When a photon is absorbed by a material, the energy transferred may cause the excitation of both the electronic and atomic structure of the compounds on the surface.

More information

VIBRATION-ROTATION SPECTRUM OF CO

VIBRATION-ROTATION SPECTRUM OF CO Rice University Physics 332 VIBRATION-ROTATION SPECTRUM OF CO I. INTRODUCTION...2 II. THEORETICAL CONSIDERATIONS...3 III. MEASUREMENTS...8 IV. ANALYSIS...9 April 2011 I. Introduction Optical spectroscopy

More information

SPECTROSCOPY MEASURES THE INTERACTION BETWEEN LIGHT AND MATTER

SPECTROSCOPY MEASURES THE INTERACTION BETWEEN LIGHT AND MATTER SPECTROSCOPY MEASURES THE INTERACTION BETWEEN LIGHT AND MATTER c = c: speed of light 3.00 x 10 8 m/s (lamda): wavelength (m) (nu): frequency (Hz) Increasing E (J) Increasing (Hz) E = h h - Planck s constant

More information

Chemistry 5325/5326. Angelo R. Rossi Department of Chemistry The University of Connecticut. January 17-24, 2012

Chemistry 5325/5326. Angelo R. Rossi Department of Chemistry The University of Connecticut. January 17-24, 2012 Symmetry and Group Theory for Computational Chemistry Applications Chemistry 5325/5326 Angelo R. Rossi Department of Chemistry The University of Connecticut angelo.rossi@uconn.edu January 17-24, 2012 Infrared

More information

Infra-red Spectroscopy

Infra-red Spectroscopy Molecular vibrations are associated with the absorption of energy (infrared activity) by the molecule as sets of atoms (molecular moieties) vibrate about the mean center of their chemical bonds. Infra-red

More information

SIMPLE QUANTUM SYSTEMS

SIMPLE QUANTUM SYSTEMS SIMPLE QUANTUM SYSTEMS Chapters 14, 18 "ceiiinosssttuu" (anagram in Latin which Hooke published in 1676 in his "Description of Helioscopes") and deciphered as "ut tensio sic vis" (elongation of any spring

More information

Ultraviolet-Visible and Infrared Spectrophotometry

Ultraviolet-Visible and Infrared Spectrophotometry Ultraviolet-Visible and Infrared Spectrophotometry Ahmad Aqel Ifseisi Assistant Professor of Analytical Chemistry College of Science, Department of Chemistry King Saud University P.O. Box 2455 Riyadh 11451

More information

Vibrations. Matti Hotokka

Vibrations. Matti Hotokka Vibrations Matti Hotokka Identify the stuff I ve seen this spectrum before. I know what the stuff is Identify the stuff Let s check the bands Film: Polymer Aromatic C-H Aliphatic C-H Group for monosubstituted

More information

Chemistry 218 Spring Molecular Structure

Chemistry 218 Spring Molecular Structure Chemistry 218 Spring 2015-2016 Molecular Structure R. Sultan COURSE SYLLABUS Email: rsultan@aub.edu.lb Homepage: http://staff.aub.edu.lb/~rsultan/ Lectures: 12:30-13:45 T, Th. 101 Chemistry Textbook: P.

More information

Vibrational Raman Spectroscopy

Vibrational Raman Spectroscopy CHEM 3421 1 Background Vibrational Raman Spectroscopy The basic theory of Raman spectroscopy and a partial description of this experimental procedure are given in your lab text 1 as experiment 35. Much

More information

The Vibrational-Rotational Spectrum of HCl

The Vibrational-Rotational Spectrum of HCl CHEM 332L Physical Chemistry Lab Revision 2.2 The Vibrational-Rotational Spectrum of HCl In this experiment we will examine the fine structure of the vibrational fundamental line for H 35 Cl in order to

More information

Chemistry 416 Spectroscopy Fall Semester 1997 Dr. Rainer Glaser

Chemistry 416 Spectroscopy Fall Semester 1997 Dr. Rainer Glaser Chemistry 416 Spectroscopy Fall Semester 1997 Dr. Rainer Glaser Third 1-Hour Examination Vibrational Spectroscopy Monday, November 24, 1997, 8:40-9:30 Name: Answer Key Question 1 (Combination) 25 Question

More information

Topic 2.11 ANALYTICAL TECHNIQUES. High Resolution Mass Spectrometry Infra-red Spectroscopy

Topic 2.11 ANALYTICAL TECHNIQUES. High Resolution Mass Spectrometry Infra-red Spectroscopy Topic 2.11 ANALYTICAL TECHNIQUES High Resolution Mass Spectrometry Infra-red Spectroscopy HIGH RESOLUTION MASS SPECTROMETRY The technique of mass spectrometry was used in Unit 1 to: a) determine the relative

More information

Infrared Spectroscopy

Infrared Spectroscopy Infrared Spectroscopy Introduction Spectroscopy is an analytical technique which helps determine structure. It destroys little or no sample. The amount of light absorbed by the sample is measured as wavelength

More information

Vibrational and Rotational Analysis of Hydrogen Halides

Vibrational and Rotational Analysis of Hydrogen Halides Vibrational and Rotational Analysis of Hydrogen Halides Goals Quantitative assessments of HBr molecular characteristics such as bond length, bond energy, etc CHEM 164A Huma n eyes Near-Infrared Infrared

More information

Chemistry 4715/8715 Physical Inorganic Chemistry Fall :20 pm 1:10 pm MWF 121 Smith. Kent Mann; 668B Kolthoff; ;

Chemistry 4715/8715 Physical Inorganic Chemistry Fall :20 pm 1:10 pm MWF 121 Smith. Kent Mann; 668B Kolthoff; ; Chemistry 4715/8715 Physical Inorganic Chemistry Fall 2017 12:20 pm 1:10 pm MWF 121 Smith Instructor: Text: be made available). Kent Mann; 668B Kolthoff; 625-3563; krmann@umn.edu R.S. Drago, Physical Methods

More information

Lab 6. Use of VSEPR to Predict Molecular Structure and IR Spectroscopy to Identify an Unknown

Lab 6. Use of VSEPR to Predict Molecular Structure and IR Spectroscopy to Identify an Unknown Lab 6. Use of VSEPR to Predict Molecular Structure and IR Spectroscopy to Identify an Unknown Prelab Assignment Before coming to lab: In addition to reading introduction of this lab handout, read and understand

More information

eigenvalues eigenfunctions

eigenvalues eigenfunctions Born-Oppenheimer Approximation Atoms and molecules consist of heavy nuclei and light electrons. Consider (for simplicity) a diatomic molecule (e.g. HCl). Clamp/freeze the nuclei in space, a distance r

More information

Principles of Molecular Spectroscopy

Principles of Molecular Spectroscopy Principles of Molecular Spectroscopy What variables do we need to characterize a molecule? Nuclear and electronic configurations: What is the structure of the molecule? What are the bond lengths? How strong

More information

Chapter 12 Mass Spectrometry and Infrared Spectroscopy

Chapter 12 Mass Spectrometry and Infrared Spectroscopy Organic Chemistry, 6 th Edition L. G. Wade, Jr. Chapter 12 Mass Spectrometry and Infrared Spectroscopy Jo Blackburn Richland College, Dallas, TX Dallas County Community College District 2006, Prentice

More information

Spectroscopy. Empirical Formula: Chemical Formula: Index of Hydrogen Deficiency (IHD)

Spectroscopy. Empirical Formula: Chemical Formula: Index of Hydrogen Deficiency (IHD) Spectroscopy Empirical Formula: Chemical Formula: Index of Hydrogen Deficiency (IHD) A)From a structure: B)From a molecular formula, C c H h N n O o X x, Formula for saturated hydrocarbons: Subtract the

More information

PAPER No. 12: ORGANIC SPECTROSCOPY MODULE No. 4: Basic principles and Instrumentation for IR spectroscopy

PAPER No. 12: ORGANIC SPECTROSCOPY MODULE No. 4: Basic principles and Instrumentation for IR spectroscopy Subject Chemistry Paper No and Title Module No and Title Module Tag Paper 12: Organic Spectroscopy Module 4: Basic principles and Instrumentation for IR spectroscopy CHE_P12_M4_e-Text TABLE OF CONTENTS

More information

obtained in Chapter 14 to this case requires that the E1 approximation

obtained in Chapter 14 to this case requires that the E1 approximation Chapter 15 The tools of time-dependent perturbation theory can be applied to transitions among electronic, vibrational, and rotational states of molecules. I. Rotational Transitions Within the approximation

More information

INPUT DESCRIPTION FOR SQM version 2.0

INPUT DESCRIPTION FOR SQM version 2.0 INPUT DESCRIPTION FOR SQM version 2.0 INTRODUCTION SQM is an add-on module for the PQS program which scales force constants to produce a Scaled Quantum Mechanical (SQM) Force Field. This can correct for

More information

A COMPUTERIZED PROGRAM FOR FINDING THE SYMMETRIES OF THE MOLECULAR NORMAL MODES OF VIBRATION

A COMPUTERIZED PROGRAM FOR FINDING THE SYMMETRIES OF THE MOLECULAR NORMAL MODES OF VIBRATION Journal of Optoelectronics and Advanced Materials Vol. 5, No. 2, June 23, p. 479-491 A COMPUTERIZED PROGRAM FOR FINDING THE SYMMETRIES OF THE MOLECULAR NORMAL MODES OF VIBRATION Ath. Trutia * University

More information

Absorption Spectra. ! Ti(H 2 O) 6 3+ appears purple (red + blue) because it absorbs green light at ~500 nm = ~20,000 cm 1.

Absorption Spectra. ! Ti(H 2 O) 6 3+ appears purple (red + blue) because it absorbs green light at ~500 nm = ~20,000 cm 1. Absorption Spectra! Colors of transition metal complexes result from absorption of a small portion of the visible spectrum with transmission of the unabsorbed frequencies. Visible Spectra of [M(H 2 O)

More information

Quiz 5 R = lit-atm/mol-k 1 (25) R = J/mol-K 2 (25) 3 (25) c = X 10 8 m/s 4 (25)

Quiz 5 R = lit-atm/mol-k 1 (25) R = J/mol-K 2 (25) 3 (25) c = X 10 8 m/s 4 (25) ADVANCED INORGANIC CHEMISTRY QUIZ 5 and FINAL December 18, 2012 INSTRUCTIONS: PRINT YOUR NAME > NAME. QUIZ 5 : Work 4 of 1-5 (The lowest problem will be dropped) FINAL: #6 (10 points ) Work 6 of 7 to 14

More information

Spectral Resolution. Spectral resolution is a measure of the ability to separate nearby features in wavelength space.

Spectral Resolution. Spectral resolution is a measure of the ability to separate nearby features in wavelength space. Spectral Resolution Spectral resolution is a measure of the ability to separate nearby features in wavelength space. R, minimum wavelength separation of two resolved features. Delta lambda often set to

More information

5.80 Small-Molecule Spectroscopy and Dynamics

5.80 Small-Molecule Spectroscopy and Dynamics MIT OpenCourseWare http://ocw.mit.edu 5.80 Small-Molecule Spectroscopy and Dynamics Fall 2008 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms. 5.80 Lecture

More information

ABC of DFT: Hands-on session 4 Molecular vibrations

ABC of DFT: Hands-on session 4 Molecular vibrations ABC of DFT: Hands-on session 4 Molecular vibrations Tutor: Alexej Bagrets Wann? 29.11.2012, 11:30-13:00 Wo? KIT Campus Süd, Flachbau Physik, Geb. 30.22, Computerpool, Raum FE-6 1 ABC of DFT, Hands-on session

More information

Spectra of Atoms and Molecules. Peter F. Bernath

Spectra of Atoms and Molecules. Peter F. Bernath Spectra of Atoms and Molecules Peter F. Bernath New York Oxford OXFORD UNIVERSITY PRESS 1995 Contents 1 Introduction 3 Waves, Particles, and Units 3 The Electromagnetic Spectrum 6 Interaction of Radiation

More information

Downloaded from UvA-DARE, the institutional repository of the University of Amsterdam (UvA)

Downloaded from UvA-DARE, the institutional repository of the University of Amsterdam (UvA) Downloaded from UvA-DARE, the institutional repository of the University of Amsterdam (UvA) http://dare.uva.nl/document/351205 File ID 351205 Filename 5: Vibrational dynamics of the bending mode of water

More information

Infrared Spectroscopy

Infrared Spectroscopy Infrared Spectroscopy (Chapter 12) 1 This reaction from Ochem 1 How do we know if it worked? The reactant is cyclohexene; the product is cyclohexanol. How can we tell the difference? Infrared Spectroscopy

More information

Chapter 2 Vibrational Spectroscopy

Chapter 2 Vibrational Spectroscopy Chapter 2 Vibrational Spectroscopy 2.1 Introduction 2.1.1 Infrared (IR) Spectroscopy The absorption of infrared (IR) radiation causes excitation of vibrations of the atoms of a molecule or the crystal

More information

Dissociation energy of the C-H bond in chloroform

Dissociation energy of the C-H bond in chloroform Dissociation energy of the C-H bond in chloroform Purpose This experiment is to determine the dissociation energy of the carbonhydrogen bond in chloroform. Dissociation energy will be calculated from fundamental

More information

INPUT DESCRIPTION FOR SQM version 1.0

INPUT DESCRIPTION FOR SQM version 1.0 INPUT DESCRIPTION FOR SQM version 1.0 INTRODUCTION SQM is an add-on module for the PQS program which scales force constants to produce a Scaled Quantum Mechanical (SQM) Force Field. This can correct for

More information

ORGANIC LABORATORY ANALYSIS REPORT. JOB NUMBER C0BEE907 PO NUMBER Credit Card. for

ORGANIC LABORATORY ANALYSIS REPORT. JOB NUMBER C0BEE907 PO NUMBER Credit Card. for ISO 17025 ORGANIC LABORATORY ANALYSIS REPORT Testing Cert. #2797.01 JOB NUMBER C0BEE907 PO NUMBER Credit Card for Prepared by: David Saperstein, PhD Scientist, FTIR, GCMS and Raman Services (Tel. 408-530-3750;

More information

Valence Bond Theory - Description

Valence Bond Theory - Description Bonding and Molecular Structure - PART 2 - Valence Bond Theory and Hybridization 1. Understand and be able to describe the Valence Bond Theory description of covalent bond formation. 2. Understand and

More information

Session #1: Theoretical background and computer simulations of molecular vibrations.

Session #1: Theoretical background and computer simulations of molecular vibrations. Raman Spectroscopy Session #1: Theoretical background and computer simulations of molecular vibrations. Goals: Understand the origin of the Raman effect. Understand the vibrational normal modes of molecules.

More information

Ethene. Introduction. The ethene molecule is planar (i.e. all the six atoms lie in the same plane) and has a high degree of symmetry:

Ethene. Introduction. The ethene molecule is planar (i.e. all the six atoms lie in the same plane) and has a high degree of symmetry: FY1006 Innføring i kvantefysikk og TFY4215 Kjemisk fysikk og kvantemekanikk Spring 2012 Chemical Physics Exercise 1 To be delivered by Friday 27.04.12 Introduction Ethene. Ethylene, C 2 H 4, or ethene,

More information

Influence of Dilution with Methanol on Fermi's Resonance inccl 4 Vibrational Spectra

Influence of Dilution with Methanol on Fermi's Resonance inccl 4 Vibrational Spectra International Journal of ChemTech Research CODEN( USA): IJCRGG ISSN : 0974-4290 Vol.6, No.1, pp 521-526, Jan-March 2014 Influence of Dilution with Methanol on Fermi's Resonance inccl 4 Vibrational Spectra

More information

Chemical Bonding II: Molecular Geometry and Hybridization of Atomic Orbitals

Chemical Bonding II: Molecular Geometry and Hybridization of Atomic Orbitals Chemical Bonding II: and Hybridization of Atomic Orbitals Chapter 10 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Valence shell electron pair repulsion (VSEPR)

More information

Degrees of Freedom and Vibrational Modes

Degrees of Freedom and Vibrational Modes Degrees of Freedom and Vibrational Modes 1. Every atom in a molecule can move in three possible directions relative to a Cartesian coordinate, so for a molecule of n atoms there are 3n degrees of freedom.

More information

Putting Near-Infrared Spectroscopy (NIR) in the spotlight. 13. May 2006

Putting Near-Infrared Spectroscopy (NIR) in the spotlight. 13. May 2006 Putting Near-Infrared Spectroscopy (NIR) in the spotlight 13. May 2006 0 Outline What is NIR good for? A bit of history and basic theory Applications in Pharmaceutical industry Development Quantitative

More information

Paper 12: Organic Spectroscopy

Paper 12: Organic Spectroscopy Subject Chemistry Paper No and Title Module No and Title Module Tag Paper 12: Organic Spectroscopy 31: Combined problem on UV, IR, 1 H NMR, 13 C NMR and Mass - Part III CHE_P12_M31 TABLE OF CONTENTS 1.

More information

SMK SULTAN ISMAIL JB, NUR FATHIN SUHANA BT AYOB

SMK SULTAN ISMAIL JB, NUR FATHIN SUHANA BT AYOB SMK SULTAN ISMAIL JB, NUR FATHIN SUHANA BT AYOB POLAR AND NON POLAR BONDS BOND POLARITY 1. Atoms with different electronegative from polar bonds (difference in EN) 2. Depicted as polar arrow : 3. Example

More information

Lecture 13 Organic Chemistry 1

Lecture 13 Organic Chemistry 1 EM 232 rganic hemistry I at hicago Lecture 13 rganic hemistry 1 Professor Duncan Wardrop February 23, 2010 1 EM 232 rganic hemistry I at hicago Spectroscopy & Spectrometry hapter 13 2 EM 232 rganic hemistry

More information

MOLECULAR LIGHT SCATTERING AND OPTICAL ACTIVITY

MOLECULAR LIGHT SCATTERING AND OPTICAL ACTIVITY MOLECULAR LIGHT SCATTERING AND OPTICAL ACTIVITY Second edition, revised and enlarged LAURENCE D. BARRON, F.R.S.E. Gardiner Professor of Chemistry, University of Glasgow 122. CAMBRIDGE UNIVERSITY PRESS

More information

Example 9.1 Using Lewis Symbols to Predict the Chemical Formula of an Ionic Compound

Example 9.1 Using Lewis Symbols to Predict the Chemical Formula of an Ionic Compound Example 9.1 Using Lewis Symbols to Predict the Chemical Formula of an Ionic Compound For Practice 9.1 Use Lewis symbols to predict the formula for the compound that forms between magnesium and nitrogen.

More information

Computer Algebraic Tools for Studying the Symmetry Properties of Molecules and Clusters. Katya Rykhlinskaya, University of Kassel

Computer Algebraic Tools for Studying the Symmetry Properties of Molecules and Clusters. Katya Rykhlinskaya, University of Kassel Computer Algebraic Tools for Studying the Symmetry Properties of Molecules and Clusters Katya Rykhlinskaya, University of Kassel 02. 06. 2005 Computational techniques in the theoretical investigations

More information

Dye molecule spectrum experiment (Experiment 34 Absorption Spectrum of a Conjugated Dye) Figure 1. Structure of dye molecules.

Dye molecule spectrum experiment (Experiment 34 Absorption Spectrum of a Conjugated Dye) Figure 1. Structure of dye molecules. Lab Reports Second Three Experiments Dye molecule spectrum experiment (Experiment 34 Absorption Spectrum of a Conjugated Dye) Some of the analysis you will do for this experiment is based on material in

More information

LAB 11 Molecular Geometry Objectives

LAB 11 Molecular Geometry Objectives LAB 11 Molecular Geometry Objectives At the end of this activity you should be able to: Write Lewis structures for molecules. Classify bonds as nonpolar covalent, polar covalent, or ionic based on electronegativity

More information

Use of group theory for the analysis of vibrational spectra

Use of group theory for the analysis of vibrational spectra Computer Physics Communications 162 (2004) 124 142 www.elsevier.com/locate/cpc Use of group theory for the analysis of vibrational spectra K. Rykhlinskaya,S.Fritzsche Fachbereich Physik, Universität Kassel,

More information

Assignment for the Infrared Spectrum of Solid Sodium Propionate from Low-Temperature Measurements in Combination with,3 C Isotopic Shifts

Assignment for the Infrared Spectrum of Solid Sodium Propionate from Low-Temperature Measurements in Combination with,3 C Isotopic Shifts Assignment for the Infrared Spectrum of Solid Sodium Propionate from Low-Temperature Measurements in Combination with,3 C Isotopic Shifts Masato Kakihana and Tadashi Nagumo Department of Chemistry, The

More information

Infrared Spectroscopy

Infrared Spectroscopy x-rays ultraviolet (UV) visible Infrared (I) microwaves radiowaves near I middle I far I λ (cm) 8 x 10-5 2.5 x 10-4 2.5 x 10-3 2.5 x 10-2 µ 0.8 2.5 25 250 ν (cm -1 ) 13,000 4,000 400 40 ν (cm -1 1 ) =

More information

Infrared Spectroscopy

Infrared Spectroscopy Reminder: These notes are meant to supplement, not replace, the laboratory manual. Infrared Spectroscopy History and Application: Infrared (IR) radiation is simply one segment of the electromagnetic spectrum

More information

Synthesis and Infrared Spectrum of Nitric Oxide 1

Synthesis and Infrared Spectrum of Nitric Oxide 1 Synthesis and Infrared Spectrum of Nitric Oxide 1 Purpose: Infrared spectroscopy is used to determine the force constant of the bond in nitric oxide. Prelab: Reading: Section 6.1 and 6.2 in Brown, LeMay,

More information

Experiment 4 Spectroscopic study of Cu(II) Complexes: Crystal Field Theory

Experiment 4 Spectroscopic study of Cu(II) Complexes: Crystal Field Theory Experiment 4 Spectroscopic study of Cu(II) Complexes: Crystal Field Theory Objective: To study the effect of ligands on crystal field splitting energy ( E) Theory The color of coordination compounds of

More information

CHEM 301: Homework assignment #12

CHEM 301: Homework assignment #12 CHEM 301: Homework assignment #12 Solutions 1. Let s practice converting between wavelengths, frequencies, and wavenumbers. (10%) Express a wavelength of 442 nm as a frequency and as a wavenumber. What

More information

Chiral Sum Frequency Generation for In Situ Probing Proton Exchange in Antiparallel β-sheets at Interfaces

Chiral Sum Frequency Generation for In Situ Probing Proton Exchange in Antiparallel β-sheets at Interfaces Supporting Information for Chiral Sum Freuency Generation for In Situ Probing Proton Exchange in Antiparallel β-sheets at Interfaces Li Fu, Deuan Xiao, Zhuguang Wang, Victor S. Batista *, and Elsa C. Y.

More information

The Absorption Spectrum of Anisole and the Anisole/CO 2 1:1-Cluster. The Influence of Intermolecular Interaction on Intramolecular Vibrations

The Absorption Spectrum of Anisole and the Anisole/CO 2 1:1-Cluster. The Influence of Intermolecular Interaction on Intramolecular Vibrations Z. Phys. Chem. 218 (2004) 123 153 by Oldenbourg Wissenschaftsverlag, München The Absorption Spectrum of Anisole and the Anisole/CO 2 1:1-Cluster. The Influence of Intermolecular Interaction on Intramolecular

More information

CHEM 6343 Advanced Computational Chemistry. Elfi Kraka, 231 FOSC, ext ,

CHEM 6343 Advanced Computational Chemistry. Elfi Kraka, 231 FOSC, ext , CHEM 6343 Advanced Computational Chemistry Class location: Lectures, time and location: Lab times and location: Instructor: Elfi Kraka, 231 FOSC, ext 8-2480, ekraka@smu.edu http://smu.edu/catco/ Office

More information

Vibration-Rotation Spectrum of HCl

Vibration-Rotation Spectrum of HCl HCl report.pb 1 Vibration-Rotation Spectrum of HCl Introduction HCl absorbs radiation in the infrared portion of the spectrum which corresponds to the molecule changing its vibrational state. A concommitant

More information

IFM Chemistry Computational Chemistry 2010, 7.5 hp LAB2. Computer laboratory exercise 1 (LAB2): Quantum chemical calculations

IFM Chemistry Computational Chemistry 2010, 7.5 hp LAB2. Computer laboratory exercise 1 (LAB2): Quantum chemical calculations Computer laboratory exercise 1 (LAB2): Quantum chemical calculations Introduction: The objective of the second computer laboratory exercise is to get acquainted with a program for performing quantum chemical

More information

Principles of Molecular Spectroscopy: Electromagnetic Radiation and Molecular structure. Nuclear Magnetic Resonance (NMR)

Principles of Molecular Spectroscopy: Electromagnetic Radiation and Molecular structure. Nuclear Magnetic Resonance (NMR) Principles of Molecular Spectroscopy: Electromagnetic Radiation and Molecular structure Nuclear Magnetic Resonance (NMR) !E = h" Electromagnetic radiation is absorbed when the energy of photon corresponds

More information

A Quantum Mechanical Model for the Vibration and Rotation of Molecules. Rigid Rotor

A Quantum Mechanical Model for the Vibration and Rotation of Molecules. Rigid Rotor A Quantum Mechanical Model for the Vibration and Rotation of Molecules Harmonic Oscillator Rigid Rotor Degrees of Freedom Translation: quantum mechanical model is particle in box or free particle. A molecule

More information

Table 8.2 Detailed Table of Characteristic Infrared Absorption Frequencies

Table 8.2 Detailed Table of Characteristic Infrared Absorption Frequencies Table 8.2 Detailed Table of Characteristic Infrared Absorption Frequencies The hydrogen stretch region (3600 2500 cm 1 ). Absorption in this region is associated with the stretching vibration of hydrogen

More information

Experiment 6: Vibronic Absorption Spectrum of Molecular Iodine

Experiment 6: Vibronic Absorption Spectrum of Molecular Iodine Experiment 6: Vibronic Absorption Spectrum of Molecular Iodine We have already seen that molecules can rotate and bonds can vibrate with characteristic energies, each energy being associated with a particular

More information

DENSITY FUNCTIONAL THEORY STUDIES ON IR SPECTRA OF THE TRIPHENYLENE DERIVATIVES. A SCALED QUANTUM MECHANICAL FORCE FIELD APPROACH

DENSITY FUNCTIONAL THEORY STUDIES ON IR SPECTRA OF THE TRIPHENYLENE DERIVATIVES. A SCALED QUANTUM MECHANICAL FORCE FIELD APPROACH Vol. 98 (2000) ACTA PHYSICA POLONICA A No. 5 Proceedings of the International Conference "Condensed Matter Physics", Jaszowiec 2000 DENSITY FUNCTIONAL THEORY STUDIES ON IR SPECTRA OF THE TRIPHENYLENE DERIVATIVES.

More information

Chem 673, Problem Set 5 Due Tuesday, December 2, 2008

Chem 673, Problem Set 5 Due Tuesday, December 2, 2008 Chem 673, Problem Set 5 Due Tuesday, December 2, 2008 (1) (a) Trigonal bipyramidal (tbp) coordination is fairly common. Calculate the group overlaps of the appropriate SALCs for a tbp with the 5 d-orbitals

More information

Organic Chemistry I Dr Alex Roche Organic chemistry is the chemistry of Carbon and its compounds. Organic molecules constitute the essence of life (fats, sugars, proteins, DNA), and also permeate our everyday

More information

CHM 451 (INORGANIC CHEMISTRY)

CHM 451 (INORGANIC CHEMISTRY) EXAM ONE PART ONE DR. MATTSON 29 SEPTEMBER 2014 CHM 451 (INORGANIC CHEMISTRY) NAME: Instructions: This exam has two parts. In Part One, only a pencil and molecular models may be used. When you have completed

More information

13 Applications of molecular symmetry and group theory

13 Applications of molecular symmetry and group theory Subject Chemistry Paper No and Title Module No and Title Module Tag 13 Applications of molecular symmetry and 26 and and vibrational spectroscopy part-iii CHE_P13_M26 TABLE OF CONTENTS 1. Learning Outcomes

More information

Chapter 10 Chemical Bonding II: Molecular Shapes, Valence Bond Theory, and Molecular Orbital Theory

Chapter 10 Chemical Bonding II: Molecular Shapes, Valence Bond Theory, and Molecular Orbital Theory 10.1 Artificial Sweeteners: Fooled by Molecular Shape 425 10.2 VSEPR Theory: The Five Basic Shapes 426 10.3 VSEPR Theory: The Effect of Lone Pairs 430 10.4 VSEPR Theory: Predicting Molecular Geometries

More information

MO Calculation for a Diatomic Molecule. /4 0 ) i=1 j>i (1/r ij )

MO Calculation for a Diatomic Molecule. /4 0 ) i=1 j>i (1/r ij ) MO Calculation for a Diatomic Molecule Introduction The properties of any molecular system can in principle be found by looking at the solutions to the corresponding time independent Schrodinger equation

More information

1.1 Is the following molecule aromatic or not aromatic? Give reasons for your answer.

1.1 Is the following molecule aromatic or not aromatic? Give reasons for your answer. Page 1 QUESTION ONE 1.1 Is the following molecule aromatic or not aromatic? Give reasons for your answer. 1.2 List four criteria which compounds must meet in order to be considered aromatic. Page 2 QUESTION

More information

6.2. Introduction to Spectroscopic states and term symbols

6.2. Introduction to Spectroscopic states and term symbols Chemistry 3820 Lecture Notes Dr. M. Gerken Page62 6.2. Introduction to Spectroscopic states and term symbols From the number of absorption bands we have already seen that usually more d-d transitions are

More information

BioMolecular Optical Spectroscopy:

BioMolecular Optical Spectroscopy: BioMolecular Optical Spectroscopy: Part 1: Infrared and Raman Vibrational Spectra Background Special Lectures for Chem 344 Fall, 2007 im Keiderling University of Illinois at Chicago tak@uic.edu Vibrational

More information