INFRARED ABSORPTION SPECTROSCOPY. References: See relevant sections in undergraduate text. Learn from your instructor how to use the spectrometer.
|
|
- Geoffrey Melton
- 6 years ago
- Views:
Transcription
1 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 interrelations: Reduced mass, µ Frequency, ν (sec -1 ) Wave number, " (cm -1 ) Rotational constant, B e (cm -1 ) "Equilibrium internuclear separation," r e Anharmonicity constant, x e Objectives: Vibration-rotation interaction constant, α e Quantum numbers υ and J P and R branches Moment of inertia, I Measurement of: 1) Vibration-rotation spectrum of HCl gas 2) Frequency of rotational lines of HCl gas Computation of: 1) Vibration-rotation interaction constant, α e 2) Rotational constant, B e 3) Fundamental vibration frequency, " 0 (cm -1 ) 4) Moment of inertia of HCl 5) Bond length of HCl, r e 6) Force constant for the H-Cl bond
2 Physical Chemistry Laboratory Chemicals: Apparatus: Conc. H 2 SO 4, NaCl and anhydrous CaCl 2 IR gas cell and filling system Research grade IR spectrometer Remarks: Theory and Spectral Analysis The spectra of molecular systems can be quite complicated and the "sorting out" of the profusion of lines and their assignment to the appropriate transitions may be a formidable task. However a proper molecular model may be used towards this objective as well as the deduction of structural parameters of the molecule of interest. The vibrational-rotational band: An infrared, high resolution spectrum of a heteronuclear diatomic molecule, such as HCl gas, consists of a vibrational-rotational band due to transitions in which both vibrational and rotational energies change. Such a band can be conveniently considered to have three portions as shown in Figure (1). 1) The zero gap is the central portion and is signified by no absorption. 2) The P- branch is the low frequency (cm -1 ) portion to the right of the zero gap. It consists of several lines which diverge towards low frequency. 3) The R- branch is the high frequency (cm -1 ) portion to the left of the zero gap. It consists of several lines which converge towards high frequency. The vibrotor model: The spectral features of the vibrationalrotational band of HCl (gas) may be explained in terms of a model for a diatomic molecule simultaneously executing both vibrational and rotational motions. The simplest model is an approximate one in which the vibrational and rotational motions are treated independently. For the vibrational motion the molecule is assumed to vibrate as a simple harmonic oscillator. The energy of the allowed vibrational levels is given by:
3 E(υ) = hν(υ + 1/2) (1) 2,.. The vibrational quantum number υ is of integral values 0, 1, The rotational motion of the molecule is that of a rigid rotor with the energy of the allowed levels given by: E( J ) = h 2 8! 2 I J( J +1) (2) The rotational quantum number J is of integral values 0, 1, 2,. The moment of inertia I is related to the internuclear distance r, and the reduced mass by: I = µr 2 (3) As a first approximation the energy of a vibrating rotating molecule (vibrotor) is the sum of expressions (1) and (2): # E(!, J ) = h"! + 1 % $ 2& + h2 8' 2 I J( J +1) (4) Each vibrational energy level consists of closely spaced rotational energy levels. A more complete expression, but not necessarily the most exact one, should include: 1) The effect of anharmonicity which is accounted for by a term involving the anharmonicity constant, x e. 2) A term involving the distortion constant, B e, which accounts for the centrifugal stretching. This results from the stretching of the non-ridged chemical bond during rotation and is important at high rotational energies (high J). 3) A term involving the vibration-rotation interaction constant, α e, which accounts for changes in r during vibrations. The vibrational-rotation energy expression of a vibrotor may be represented by:
4 Physical Chemistry Laboratory ( ) = E (!, J) T!, J (4) hc T (!, J) = " #! + 1 % e $ 2 & ' x "! # % e e $ 2 & + B e J( J +1) + D e J 2 ( J +1 ) 2 ' ( #! + 1 % e $ 2 & J( J + 1) (5) where T (υ, J) is in cm -1. The frequency " e (cm -1 ) refers to the frequency of the molecule vibrating about its equilibrium internuclear separation r e. The rotational constant B e is defined by (c is the speed of light, cm/s): B e = h 8! 2 Ic (6) Selection Rules: The fine structure of the P- and R- branches represents transitions from a particular rotational level (J = J") in a given vibrational state (υ = υ") to a different rotational level (J = J') in an excited vibrational state (υ = υ'). The superscripts (') and (") refer to high and low vibrational states, respectively. A common pitfall for students first exposed to spectroscopy is to confuse energy levels T (υ, J) with transitions between energy levels Δ[T (υ, J)] where Δ [T(υ, J)] = T (υ', J') - T (υ", J") (7) It is the latter which is directly observed. For transitions to be allowed the selection rules for a diatomic molecule to be infrared active are: 1) Δυ = ± 1 2) ΔJ = ± 1 3) Change to dipole moment 0 during vibration. A homonuclear diatomic molecule, being nonpolar, has a dipole moment equal to zero, and invariant, unless the molecule is in a unique chemical environment. Thus, homonuclear diatomic molecules are, in general, infrared inactive. In the present experiment the transitions take place from
5 various J" - levels of the vibrational ground state (υ" = 0) to J' - levels of the first excited vibrational state (υ' = 1). Frequencies of the P- and R- lines: From the selection rules, and application of equation (7) with proper substitution from eq (5) the frequencies (cm -1 ) of the P- and R- lines are: P- branch: ΔJ = -1 ; which is J' - J" where J" = 1, 2, 3 R- branch: ΔJ = + 1 ; J' = J" + 1! P =! 0 " 2( B e " # e )J " # e J 2 ; (8) and! R =! 0 "( 2B e " 3# e ) + ( 2B e " 2# e )J " a e J 2 (9)! 0 =! e " 2x e! e (10) where " 0 is the frequency of the forbidden transition (ΔJ = 0). It corresponds to the missing line, somewhere near the midpoint in the zero gap. In the derivation of equations (8) and (9) from equation (7) the term in D e is neglected. The frequency of the P- and R- branches, in the observed spectrum can be represented by the empirical equation: where m is a running number which is: +1, +2, +3, for the R- branch " = c + dm + em 2 (11) and -1, -2, -3, for the P- branch. A single equation similar to equation (11) may be obtained from equations (8) and (7) by substituting for J as follows: for the P- branch (equation 8): J = -m and for the R- branch (equation 9): J = m - 1 This leads to:! =! 0 " 2( B e "# e )m "# e m 2 (12)
6 Physical Chemistry Laboratory The separation between adjacent lines in each branch is given by:! " ( m) = "( m +1) # "( m) = 2B e # 3$ e ( ) # 2$ e m (13) ( ) as ordinate and m as abscissa, a If we plot values of " # m fit of the best straight line through the points has its slope equal to -2α e, yielding the vibrotor interaction constant. If the points are from a sufficiently highly resolved spectrum and are plotted on a sufficiently large scale, the best fit will be a slightly curved line. The slope of the tangent to the curve at m = 0 should be used to obtain α e. The intercept of the curve with the " #( m) axis gives a value from which B e, the rotational constant, is obtained. The value of " 0 is obtained from equation (12) by using α e, B e and with data from an m that has a " # that falls on the least squares line. The moment of inertia, and hence the bond length, are obtained from the definition for B e. Procedure: Specific instructions for the operation of the infrared spectrometer to be used will be given in the laboratory. This is a precision research instrument -- use it carefully. If in doubt about anything after being instructed in its use, ask the instructor. Don't take chances with expensive equipment when you are unsure. The gas cell is constructed from a 10 cm length of large diameter PTFE tubing with stopcocks attached. Infraredtransparent windows are attached to the ends by an adhesive or by mechanical clamps or both. The windows are cut from large crystals of NaCl and are easily fogged by moisture from atmosphere or skin. Never touch the windows and store the cell in a desiccator when not in use. Connect the dropping funnel and flask (properly supported by a ring stand) to the drying tube and cell, with stopcocks open. This setup must be in a fume hood. To about 25 g NaCl, slowly add about 25 ml concentrated sulfuric acid to produce a steady evolution of gas, probably not all the acid will be needed. Check the open end of the cell for HCl evolution as evidenced by white fumes and/or blue litmus turning pink. Allow the gas to continue passing through the cell for a few minutes then disconnect and close the stopcocks. This usually provides
7 a reasonable partial pressure of HCl in the cell. Record the spectrum on a fresh piece of paper using the highest expansion of wavelength scale available with the instrument. This spectrum should run between values of 2700 cm -1 and 3000 cm -1 the frequencies as recorded by the FTIR are then used for the calculations. Results and Calculations: 1) In a single table, list the following information for each identifiable peak in your high resolution spectrum: ( ) J,! 0, P or R branch, m,! " m 2) Using the method given above, i.e. the plot of Δν~ (m) vs. m, from the tabulated data compute: a) α e b) c) B e! 0 3) Using the value of B e computed above, obtain a value for I, the moment of inertia of the HCl molecule. 4) Using x kg and x kg for the masses of individual atoms of hydrogen and chlorine, respectively, compute the reduced mass, µ, and bond length r e (in Angstroms and nm) for HCl from I = µ r e 2. 5) Calculate the force constant for the HCl bond. 6) Repeat steps 1-5 for the DCl spectrum given by the instructor.
Experiment 4 INFRARED SPECTROSCOPY
Experiment INFRARED SPECTROSCOPY Infrared (IR) spectroscopy is one tool for the study of molecular structure. In the case of diatomic molecules, one can extract bond lengths and bond force constants from
More informationVibration-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 informationThe 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 informationCHM Physical Chemistry II Chapter 12 - Supplementary Material. 1. Einstein A and B coefficients
CHM 3411 - Physical Chemistry II Chapter 12 - Supplementary Material 1. Einstein A and B coefficients Consider two singly degenerate states in an atom, molecule, or ion, with wavefunctions 1 (for the lower
More informationNORTH CAROLINA STATE UNIVERSITY Department of Chemistry. Physical Chemistry CH437 Problem Set #4 Due Date: September 22, 2015
NORTH CAROLINA STATE UNIVERSITY Department of Chemistry Name Physical Chemistry CH437 Problem Set #4 Due Date: September 22, 2015 Using a Fourier Transform Infra-red (FTIR) spectrometer we can obtain sufficiently
More information24/ Rayleigh and Raman scattering. Stokes and anti-stokes lines. Rotational Raman spectroscopy. Polarizability ellipsoid. Selection rules.
Subject Chemistry Paper No and Title Module No and Title Module Tag 8/ Physical Spectroscopy 24/ Rayleigh and Raman scattering. Stokes and anti-stokes lines. Rotational Raman spectroscopy. Polarizability
More informationeigenvalues 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 informationEXPERIMENT 12. SPECTROSCOPIC STUDIES OF HCL AND DCL
EXPERIMENT 12. SPECTROSCOPIC STUDIES OF HCL AND DCL High resolution infrared spectroscopy is one of the most useful tools for investigating the structure of small molecules. In this experiment you will
More informationPAPER No. : 8 (PHYSICAL SPECTROSCOPY) MODULE NO. : 23 (NORMAL MODES AND IRREDUCIBLE REPRESENTATIONS FOR POLYATOMIC MOLECULES)
Subject Chemistry Paper No and Title Module No and Title Module Tag 8/ Physical Spectroscopy 23/ Normal modes and irreducible representations for polyatomic molecules CHE_P8_M23 TABLE OF CONTENTS 1. Learning
More informationVibrational 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 informationV( 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 information2. Infrared spectroscopy
2. Infrared spectroscopy 2-1Theoretical principles An important tool of the organic chemist is Infrared Spectroscopy, or IR. IR spectra are acquired on a special instrument, called an IR spectrometer.
More informationCHAPTER 13 LECTURE NOTES
CHAPTER 13 LECTURE NOTES Spectroscopy is concerned with the measurement of (a) the wavelengths (or frequencies) at which molecules absorb/emit energy, and (b) the amount of radiation absorbed at these
More informationAn Aside: Application of Rotational Motion. Vibrational-Rotational Spectroscopy
An Aside: Application of Rotational Motion Vibrational-Rotational Spectroscopy Rotational Excited States of a Diatomic Molecule are Significantly Populated at Room Temperature We can estimate the relative
More informationPhysical Chemistry - Problem Drill 15: Vibrational and Rotational Spectroscopy
Physical Chemistry - Problem Drill 15: Vibrational and Rotational Spectroscopy No. 1 of 10 1. Internal vibration modes of a molecule containing N atoms is made up of the superposition of 3N-(5 or 6) simple
More informationMolecular 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 informationSynthesis 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 informationVIBRATION-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 informationTHE VIBRATIONAL SPECTRA OF A POLYATOMIC MOLECULE (Revised 3/27/2006)
THE VIBRATIONAL SPECTRA OF A POLYATOMIC MOLECULE (Revised 3/27/2006) 1) INTRODUCTION The vibrational motion of a molecule is quantized and the resulting energy level spacings give rise to transitions in
More informationVibrational Spectroscopy
Vibrational Spectroscopy In this part of the course we will look at the kind of spectroscopy which uses light to excite the motion of atoms. The forces required to move atoms are smaller than those required
More information16.1 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( ) electron gives S = 1/2 and L = l 1
Practice Modern Physics II, W018, Set 1 Question 1 Energy Level Diagram of Boron ion B + For neutral B, Z = 5 (A) Draw the fine-structure diagram of B + that includes all n = 3 states Label the states
More informationVibrational-Rotational Spectroscopy. Spectroscopy
Applied Spectroscopy Vibrational-Rotational Spectroscopy Recommended Reading: Banwell and McCash Section 3.2, 3.3 Atkins Section 6.2 Harmonic oscillator vibrations have the exact selection rule: and the
More informationMolecular spectroscopy Multispectral imaging (FAFF 020, FYST29) fall 2017
Molecular spectroscopy Multispectral imaging (FAFF 00, FYST9) fall 017 Lecture prepared by Joakim Bood joakim.bood@forbrf.lth.se Molecular structure Electronic structure Rotational structure Vibrational
More information( )( s 1
Chemistry 362 Dr Jean M Standard Homework Problem Set 6 Solutions l Calculate the reduced mass in kg for the OH radical The reduced mass for OH is m O m H m O + m H To properly calculate the reduced mass
More informationLaser Induced Fluorescence of Iodine
Laser Induced Fluorescence of Iodine (Last revised: FMH 29 Sep 2009) 1. Introduction In this experiment we are going to study the laser induced fluorescence of iodine in the gas phase. The aim of the study
More informationThe Iodine Spectrum. and
The Iodine Spectrum George Long Department of Chemistry Indiana University of Pennsylvania Indiana, PA 15705 grlong@grove.iup.edu and Department of Chemistry, Medical Technology, and Physics Monmouth University
More informationTHE VIBRATIONAL SPECTRUM OF A POLYATOMIC MOLECULE (Revised 4/7/2004)
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
More information5.3 Rotational Raman Spectroscopy General Introduction
5.3 Rotational Raman Spectroscopy 5.3.1 General Introduction When EM radiation falls on atoms or molecules, it may be absorbed or scattered. If λis unchanged, the process is referred as Rayleigh scattering.
More informationPhysical Chemistry II Laboratory
Kuwata Spring 2003 Physical Chemistry II Laboratory The Rovibrational Spectra of H 35 Cl and H 37 Cl Using FTIR Write-Up Due Date: Thursday, April 17 (You may record spectra and write your reports in teams
More informationExercises 16.3a, 16.5a, 16.13a, 16.14a, 16.21a, 16.25a.
SPECTROSCOPY Readings in Atkins: Justification 13.1, Figure 16.1, Chapter 16: Sections 16.4 (diatomics only), 16.5 (omit a, b, d, e), 16.6, 16.9, 16.10, 16.11 (omit b), 16.14 (omit c). Exercises 16.3a,
More informationExperiment 3: The Rovibrational Spectrum of HCl (was Experiment 4 in the syllabus, but the original Experiment 3 was canceled)
Varberg and Kuwata Chemistry 312 Spring 28 Experiment 3: The Rovibrational Spectrum of HCl (was Experiment 4 in the syllabus, but the original Experiment 3 was canceled) Meet for lab on Thursday, April
More informationAdvanced Chemistry 2008
Advanced Chemistry 008 Vibration - Rotation Spectrum of a Diatomic Molecule Analysis of the Fundamental Bands of the H 9 Br and H 8 Br Molecules 0 The vibration-rotation spectrum of the HBr molecule in
More information6.2 Polyatomic Molecules
6.2 Polyatomic Molecules 6.2.1 Group Vibrations An N-atom molecule has 3N - 5 normal modes of vibrations if it is linear and 3N 6 if it is non-linear. Lissajous motion A polyatomic molecule undergoes a
More informationNPTEL/IITM. Molecular Spectroscopy Lectures 1 & 2. Prof.K. Mangala Sunder Page 1 of 15. Topics. Part I : Introductory concepts Topics
Molecular Spectroscopy Lectures 1 & 2 Part I : Introductory concepts Topics Why spectroscopy? Introduction to electromagnetic radiation Interaction of radiation with matter What are spectra? Beer-Lambert
More informationSpectroscopy in Inorganic Chemistry. Vibration and Rotation Spectroscopy
Spectroscopy in Inorganic Chemistry Vibrational energy levels in a diatomic molecule f = k r r V = ½kX 2 Force constant r Displacement from equilibrium point 2 X= r=r-r eq V = ½kX 2 Fundamental Vibrational
More informationWorkshop 4: Diatomic molecule vibrational and rotational spectra CH351 Physical Chemistry, Fall 2004
Workshop 4: Diatomic molecule vibrational and rotational spectra CH35 Physical Chemistry, Fall 004 http://quantum.bu.edu/courses/ch35/pltl/4.pdf Last updated Monday, November 9, 004 6:59:3-05:00 Copyright
More informationPhysical Chemistry Lab II CHEM 4644 Spring 2011 Final Exam 5 questions at 3 points each equals 15 total points possible.
Physical Chemistry Lab II Name: KEY CHEM 4644 Spring 2011 Final Exam 5 questions at 3 points each equals 15 total points possible. Constants: c = 3.00 10 8 m/s h = 6.63 10-34 J s 1 Hartree = 4.36 10-18
More informationLecture 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 informationModel for vibrational motion of a diatomic molecule. To solve the Schrödinger Eq. for molecules, make the Born- Oppenheimer Approximation:
THE HARMONIC OSCILLATOR Features Example of a problem in which V depends on coordinates Power series solution Energy is quantized because of the boundary conditions Model for vibrational motion of a diatomic
More information6.05 Computational Raman Spectroscopy
2nd/3rd year Physical Chemistry Practical Course, Oxford University 6.05 Computational Raman Spectroscopy (5 points) Raman spectra are obtained by irradiating a sample with very intense monochromatic radiation,
More informationInfrared Spectroscopy
Infrared Spectroscopy The Interaction of Light with Matter Electric fields apply forces to charges, according to F = qe In an electric field, a positive charge will experience a force, but a negative charge
More informationWhat happens when light falls on a material? Transmission Reflection Absorption Luminescence. Elastic Scattering Inelastic Scattering
Raman Spectroscopy What happens when light falls on a material? Transmission Reflection Absorption Luminescence Elastic Scattering Inelastic Scattering Raman, Fluorescence and IR Scattering Absorption
More information4. Molecular spectroscopy. Basel, 2008
4. Molecular spectroscopy Basel, 008 4.4.5 Fluorescence radiation The excited molecule: - is subject to collisions with the surrounding molecules and gives up energy by decreasing the vibrational levels
More informationChemistry 2. Assumed knowledge
Chemistry 2 Lecture 8 IR Spectroscopy of Polyatomic Molecles Assumed knowledge There are 3N 6 vibrations in a non linear molecule and 3N 5 vibrations in a linear molecule. Only modes that lead to a change
More informationPhysical Chemistry Laboratory II (CHEM 337) EXPT 9 3: Vibronic Spectrum of Iodine (I2)
Physical Chemistry Laboratory II (CHEM 337) EXPT 9 3: Vibronic Spectrum of Iodine (I2) Obtaining fundamental information about the nature of molecular structure is one of the interesting aspects of molecular
More informationIntroduction 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 informationLecture 4: Polyatomic Spectra
Lecture 4: Polyatomic Spectra 1. From diatomic to polyatomic Ammonia molecule A-axis. Classification of polyatomic molecules 3. Rotational spectra of polyatomic molecules N 4. Vibrational bands, vibrational
More informationSIMPLE 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 informationQUANTUM CHEMISTRY PROJECT 3: PARTS B AND C
Chemistry 460 Fall 2017 Dr. Jean M. Standard November 6, 2017 QUANTUM CHEMISTRY PROJECT 3: PARTS B AND C PART B: POTENTIAL CURVE, SPECTROSCOPIC CONSTANTS, AND DISSOCIATION ENERGY OF DIATOMIC HYDROGEN (20
More informationMolecular Constants of CO by Infrared Spectroscopy
Molecular Constants of CO by Infrared Spectroscopy Purpose This experiment uses infrared spectroscopy to determine the bond length, vibration frequency, anharmonicity, and other properties of the carbon
More informationChem 442 Review of Spectroscopy
Chem 44 Review of Spectroscopy General spectroscopy Wavelength (nm), frequency (s -1 ), wavenumber (cm -1 ) Frequency (s -1 ): n= c l Wavenumbers (cm -1 ): n =1 l Chart of photon energies and spectroscopies
More informationIntroduction to Franck-Condon Factors
Introduction to Franck-Condon Factors Theresa Julia Zielinski Monmouth University Department of Chemistry, Medical Technology, and Physics West Long Branch, NJ 07764 tzielins@monmouth.edu and La Salle
More informationChapter 8 Problem Solutions
Chapter 8 Problem Solutions 1. The energy needed to detach the electron from a hydrogen atom is 13.6 ev, but the energy needed to detach an electron from a hydrogen molecule is 15.7 ev. Why do you think
More informationPAPER 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 informationCHEM Atomic and Molecular Spectroscopy
CHEM 21112 Atomic and Molecular Spectroscopy References: 1. Fundamentals of Molecular Spectroscopy by C.N. Banwell 2. Physical Chemistry by P.W. Atkins Dr. Sujeewa De Silva Sub topics Light and matter
More information5.61 Physical Chemistry Final Exam 12/16/09. MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Chemistry Chemistry Physical Chemistry
5.6 Physical Chemistry Final Exam 2/6/09 MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Chemistry Chemistry - 5.6 Physical Chemistry Final Examination () PRINT your name on the cover page. (2) It
More informationLecture 8. Assumed knowledge
Chemistry 2 Lecture 8 IR Spectroscopy of Polyatomic Molecles Assumed knowledge There are 3N 6 vibrations in a non linear molecule and 3N 5 vibrations in a linear molecule. Only modes that lead to a change
More informationAdvanced 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 informationEXPERIMENT: LIMITING REAGENT. NOTE: Students should have moles of reactants in DATASHEET converted into masses in grams prior to the lab period.
Revised 12/2015 EXPERIMENT: LIMITING REAGENT Chem 1104 Lab NOTE: Students should have moles of reactants in DATASHEET converted into masses in grams prior to the lab period. INTRODUCTION Limiting reactant
More informationMOLECULAR ENERGY LEVELS DR IMRANA ASHRAF
MOLECULAR ENERGY LEVELS DR IMRANA ASHRAF OUTLINE q q q q MOLECULE MOLECULAR ORBITAL THEORY MOLECULAR TRANSITIONS INTERACTION OF RADIATION WITH MATTER q TYPES OF MOLECULAR ENERGY LEVELS q MOLECULE q In
More informationIR Spectrography - Absorption. Raman Spectrography - Scattering. n 0 n M - Raman n 0 - Rayleigh
RAMAN SPECTROSCOPY Scattering Mid-IR and NIR require absorption of radiation from a ground level to an excited state, requires matching of radiation from source with difference in energy states. Raman
More informationEffect of mass attached to the spring: 1. Replace the small stopper with the large stopper. Repeat steps 3-9 for each spring set.
EXERCISE 1: Representing molecular vibrations with spring oscillations A spring is a common model for covalent chemical bonds. One of the interesting interpretations of quantum mechanics is that bonds
More informationRotational Raman Spectroscopy
Rotational Raman Spectroscopy If EM radiation falls upon an atom or molecule, it may be absorbed if the energy of the radiation corresponds to the separation of two energy levels of the atoms or molecules.
More informationTHEORY OF MOLECULE. A molecule consists of two or more atoms with certain distances between them
THEORY OF MOLECULE A molecule consists of two or more atoms with certain distances between them through interaction of outer electrons. Distances are determined by sum of all forces between the atoms.
More informationAtoms, Molecules and Solids (selected topics)
Atoms, Molecules and Solids (selected topics) Part I: Electronic configurations and transitions Transitions between atomic states (Hydrogen atom) Transition probabilities are different depending on the
More informationSpectroscopy in Inorganic Chemistry. Vibration and Rotation Spectroscopy
Spectroscopy in Inorganic Chemistry Symmetry requirement for coupling combination bands and Fermi resonance 2 3 V 3 1505 cm -1 (R, IR) E' stretches v 1 888 cm -1 (R) A 1 ' stretch V 2 718 cm -1 (IR) A
More informationYour Name: Question 1. Electromagnetic Spectrum. (10, diagrams adopted from images in the online public domain)
Question 1. Electromagnetic Spectrum. (10, diagrams adopted from images in the online public domain) (a) In the yellow-shaded areas, provide the most appropriate term to describe the wave. (5 points) (b)
More informationSymmetric 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 informationATMO 551a Fall Resonant Electromagnetic (EM) Interactions in Planetary atmospheres. Electron transition between different electron orbits
Resonant Electromagnetic (EM) Interactions in Planetary atmospheres There are three classes of energy states that interact with EM radiation that we are interested in to understand how light (EM radiation)
More informationCHEM 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 informationChemistry 881 Lecture Topics Fall 2001
Chemistry 881 Lecture Topics Fall 2001 Texts PHYSICAL CHEMISTRY A Molecular Approach McQuarrie and Simon MATHEMATICS for PHYSICAL CHEMISTRY, Mortimer i. Mathematics Review (M, Chapters 1,2,3 & 4; M&S,
More informationPhysical Chemistry II Exam 2 Solutions
Chemistry 362 Spring 2017 Dr Jean M Standard March 10, 2017 Name KEY Physical Chemistry II Exam 2 Solutions 1) (14 points) Use the potential energy and momentum operators for the harmonic oscillator to
More informationVibronic Spectra of Diatomic Molecules and the Birge-Sponer Extrapolation
Vibronic Spectra of Diatomic Molecules and the Birge-Sponer Extrapolation George M Shalhoub Department of Chemistry LaSalle University Philadelphia, PA 9 shalhoub@lasalleedu and Theresa Julia Zielinski
More informationVibrational spectroscopy., 2017 Uwe Burghaus, Fargo, ND, USA
Vibrational spectroscopy, 017 Uwe Burghaus, Fargo, ND, USA CHEM761 Rotational spectroscopy is concerned with the measurement of the energies of transitions between quantized rotational states... microwave
More informationExperiment 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( ) x10 8 m. The energy in a mole of 400 nm photons is calculated by: ' & sec( ) ( & % ) 6.022x10 23 photons' E = h! = hc & 6.
Introduction to Spectroscopy Spectroscopic techniques are widely used to detect molecules, to measure the concentration of a species in solution, and to determine molecular structure. For proteins, most
More informationExperiment #9. Atomic Emission Spectroscopy
Introduction Experiment #9. Atomic Emission Spectroscopy Spectroscopy is the study of the interaction of light with matter. This interaction can be in the form of the absorption or the emission of electromagnetic
More informationVibrations 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 informationAssignment: Read Atkins, Chapter 27 sections 7 and 8 or McQuarrie and Simon, Chapter 30 sections 7 and 10, before coming to lab on Monday
Classical Trajectory 1 Classical Trajectory Calculations H + H-F H-H + F Assignment: Read Atkins, Chapter 27 sections 7 and 8 or McQuarrie and Simon, Chapter 30 sections 7 and 10, before coming to lab
More informationRadiative Transfer and Molecular Lines Sagan Workshop 2009
Radiative Transfer and Molecular Lines Sagan Workshop 2009 Sara Seager Trent Schindler Trent Schindler MIT Lecture Contents Overview of Equations for Planetary Atmospheres Radiative Transfer Thermal Inversions
More informationChem120a : Exam 3 (Chem Bio) Solutions
Chem10a : Exam 3 (Chem Bio) Solutions November 7, 006 Problem 1 This problem will basically involve us doing two Hückel calculations: one for the linear geometry, and one for the triangular geometry. We
More informationDetermination of the K a Value and Molar Mass of an Unknown Weak Acid
10 Determination of the K a Value and Molar Mass of an Unknown Weak Acid Introduction In this experiment you will titrate a monoprotic weak acid with a strong base, and measure the titration curve with
More informationDetermination of Orthophosphate Ion
Determination of Orthophosphate Ion Introduction Phosphorous, in the form of phosphate, is one of several important elements in the growth of plants. Excessive algae growth in water is stimulated by the
More informationChemistry 543--Final Exam--Keiderling May 5, pm SES
Chemistry 543--Final Exam--Keiderling May 5,1992 -- 1-5pm -- 174 SES Please answer all questions in the answer book provided. Make sure your name is clearly indicated and that the answers are clearly numbered,
More informationExperiment#1 Beer s Law: Absorption Spectroscopy of Cobalt(II)
: Absorption Spectroscopy of Cobalt(II) OBJECTIVES In successfully completing this lab you will: prepare a stock solution using a volumetric flask; use a UV/Visible spectrometer to measure an absorption
More informationhigh energy state for the electron in the atom low energy state for the electron in the atom
Atomic Spectra Objectives The objectives of this experiment are to: 1) Build and calibrate a simple spectroscope capable of measuring wavelengths of visible light. 2) Measure several wavelengths of light
More information(2) Read each statement carefully and pick the one that is incorrect in its information.
Organic Chemistry - Problem Drill 17: IR and Mass Spectra No. 1 of 10 1. Which statement about infrared spectroscopy is incorrect? (A) IR spectroscopy is a method of structure determination based on the
More informationEXPERIMENT THREE THE CANNIZARO REACTION: THE DISPROPORTIONATION OF BENZALDEHYDE
EXPERIMENT THREE THE CANNIZARO REACTION: THE DISPROPORTIONATION OF BENZALDEHYDE H C O HO C O H H C OH KOH 2x + DISCUSSION In planning the laboratory schedule, it should be observed that this experiment
More informationHeadspace Raman Spectroscopy
ELECTRONICALLY REPRINTED FROM SEPTEMBER 2014 Molecular Spectroscopy Workbench Raman Spectroscopy We examine vapor-phase Raman spectroscopy through the acquisition of spectra from gas molecules confined
More informationVibrational Spectra (IR and Raman) update Tinoco has very little, p.576, Engel Ch. 18, House Ch. 6
Vibrational Spectra (IR and Raman)- 2010 update Tinoco has very little, p.576, Engel Ch. 18, House Ch. 6 Born-Oppenheimer approx. separate electron-nuclear Assume elect-nuclear motion separate, full wave
More informationCollisionally Excited Spectral Lines (Cont d) Diffuse Universe -- C. L. Martin
Collisionally Excited Spectral Lines (Cont d) Please Note: Contrast the collisionally excited lines with the H and He lines in the Orion Nebula spectrum. Preview: Pure Recombination Lines Recombination
More informationChemistry 483 Lecture Topics Fall 2009
Chemistry 483 Lecture Topics Fall 2009 Text PHYSICAL CHEMISTRY A Molecular Approach McQuarrie and Simon A. Background (M&S,Chapter 1) Blackbody Radiation Photoelectric effect DeBroglie Wavelength Atomic
More informationChem Page VII - 1 LAB MANUAL Dipole Moment 07_dipo131.docx EXPERIMENT VII
Chem 366-3 Page VII - 1 EXPERIMENT VII DIPOLE MOMENT OF POLAR MOLECULES IN SOLUTION (S&G 5 th ed. Expt 31, 6 th and 7 th eds. Expt. 30, 8 th ed. Expt.29) The heterodyne-beat frequency method is used to
More informationIntroduction to Vibrational Spectroscopy
Introduction to Vibrational Spectroscopy Harmonic oscillators The classical harmonic oscillator The uantum mechanical harmonic oscillator Harmonic approximations in molecular vibrations Vibrational spectroscopy
More information12AL Experiment 11 (3 days): Nucleophilic Substitution Reactions
12AL Experiment 11 (3 days): Nucleophilic Substitution Reactions Instructor note: Day 1 (half of the class); Day 2 (other half); Day 3 (everyone to finish up any separation & purification steps etc). Initial
More informationA56. Raman Spektroscopy. Jan Publisher: Institute of Physical Chemistry
Physikalische-Chemisches Praktikum für Anfänger A56 Raman Spektroscopy Jan. 2017 Publisher: Institute of Physical Chemistry 1 Objectives 1. Take the Raman spectra of CO 2 (s), CS 2 (l), C 6 H 6 (l) and
More informationMolecular spectroscopy
10 Molecular spectroscopy Answers to worked examples W.E. 10.1 Using the Beer-Lambert law (on p. 462 in Chemistry 3 ) What concentration of the solution is required to absorb 35% of the light at the same
More informationA 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 informationInfrared Spectroscopy An Instrumental Method for Detecting Functional Groups
Infrared Spectroscopy An Instrumental Method for Detecting Functional Groups 1 The Electromagnetic Spectrum Infrared Spectroscopy I. Physics Review Frequency, υ (nu), is the number of wave cycles that
More information