6 Topics to be covered. What is spectroscopy? 2Y Spectroscopy: Topic 1. Introduction to Spectroscopy. Quantitative Spectroscopy:
|
|
- Benjamin Dean
- 6 years ago
- Views:
Transcription
1 Spectroscopy 3 lectures leading to one exam question Texts: Elements of Physical Chemistry 4 th ed. by Atkins & de Paula, Chapter 19 & Chapter 20 Foundations of Spectroscopy By Duckett & Gilbert, Chapter Various Specialist texts in Hardiman Library Need this for CH205 in second semester. Need this for 3, 4 year chemistry. Notes & Links available on my website. This version 22/11/2010: minor errors corrected. 6 Topics to be covered Introduction to Spectroscopy. Quantitative Spectroscopy: Beer-Lambert. Electronic spectroscopy. Vibrational Spectroscopy: FT-IR and Raman spectroscopy. Energies of Vibrational transitions. Polyatomic Vibrational spectroscopy Y Spectroscopy: Topic 1 Introduction to spectroscopy: Electromagnetic spectrum. Quantisation of energy & energy levels. Selection rules. Bohr condition. Absorption, Emission, & Scattering Spectroscopies. Need to Know: EM spectrum, how to interconvert from wavelength, wavenumber, or frequency to energy, and the different types of spectroscopy. What is spectroscopy? Interaction of electromagnetic radiation with matter: Absorption. Emission. Scattering. Many different scales: Astronomy (single stars). Microscopy (single molecules). Everything from forensics to living cells 3 4 Page 1
2 5 Spectrum (pl. spectra) Map of the energy states of a compound or molecule. In principle, each spectrum is unique. Spectrum is a molecular fingerprint : Tool for qualitative analysis (FT-IR, Raman). Also ideal for quantitative analysis via the Beer- Lambert Law: UV-Vis (exp. 2)..protein conc. in biochemistry. FT-IR, NIR, Raman spectroscopies in industry. The Electromagnetic Spectrum Region Frequency s 1 Wavelength Radio F m Micro Wave mm IR µm UV-VIS nm X-RAY pm γ-ray pm 6 Wavenumber (cm -1 ) Quantisation of energy. Quantum Theory.molecules exists in discrete energy levels (electronic, vibrational, rotational). Transitions between allowed energy states. Spectra reflect these defined changes (band structure). 500 nm = 0.5 x10-4 cm = 20,000 cm -1 Visible (high energy) 1000 nm = 1 x10-4 cm = 10,000 cm -1 Near IR 2000 nm = 2 x10-4 cm = 5,000 cm nm = 5 x10-4 cm = 2000 cm -1 IR (low energy) 7 8 INTENSITY (arb. units) Cocaine hydrochloride raman shift, cm -1. Page 2
3 E Schematic molecular energy levels UV-VISIBLE INFRARED MICROWAVE Selection Rules There are rules for each type of spectroscopy. In general: Interaction between oscillating electric (or magnetic field) with the dipole moment of the molecule. Transitions only between allowed energy levels (QChem). two electric charges +q and q separated by a distance R ELECTRONIC VIBRATIONAL ROTATIONAL TRANSLATIONAL 9 10 The Bohr frequency condition: E (molecule) = E (photon) PHOTON ENERGY Absorption spectroscopy Can refer to the absorption of any frequency of radiation, most common are: UV-visible absorption (electronic) IR absorption (vibrational) Microwave absorption (rotational) These are all types of molecular spectroscopy. Energy of the radiation energy of transition. 11 BEFORE DURING AFTER ε = hν = hc / λ = hcν 12 Page 3
4 Absorption spectrometer Light absorbed by sample. Grating/frequency analyser Single channel (PMT) or multichannel (CCD) detectors (visible) Emission spectroscopy Emission of any frequency of radiation. Concerned with the properties of emitted photons. UV-VIS-NIR (electronic transitions): Fluorescence, Phosphorescence, Chemiluminescence, photoluminescence. Fluorescence underpins nearly all of modern biology. Based on chemistry & physics Scattering spectroscopy We look at how light scatters from molecules: Not absorbed, doesn t have to pass thru. Can use everything from neutrons to x-rays etc. Most Important is Raman spectroscopy: Molecular technique. Great for forensics etc. 2Y Spectroscopy: Topic 2 Quantitative spectroscopy: Beer-Lambert Law. Absorbance & Transmittance. Molar Absorption co-efficient. Calculations. Limitations. Know the Beer-Lambert law & calculations, how to interconvert from transmittance to absorbance. Limitations of method. Sec & 19.2: Atkins (Elements of Phys. Chem, 4 ed ) Page 4
5 17 I 0 Beer-Lambert Law: Quantitative Sample, Concentration C I T Pathlength, l At a fixed temperature and a single wavelength: the intensity of light, I T, transmitted through a sample depends upon: the pathlength or sample thickness,l the concentration of the absorbing species, C the incident light intensity, I 0 18 Beer Lambert Law I = I 10 λ ( e l C) T 0... at constant Temp. and a single wavelength ( ) e molar absorptivity, l pathlength, C concentration of absorbing species log(i ) = log(i ) e l C.... rearrange to: T 0 log(i ) log(i ) = e l C... we know: log a T 0 0 IT a log b =log b ( ) ( ) I T I 0 log = e l C... rearrange to: log = e l C, I 0 I T I absorbance, A = log A = e l C Application of Beer-Lambert law (1) Calculate: Molar abs. Co-eff. of Tryptophan (comp. of proteins) 280 nm 1 mm pathlength Needed Info Aqueous solution, 0.50 mmol L -1 54% of light passes through A = - log T = εlc step 1, write eqn. ε = - log T / l C step 2, rearrange eqn. Application of Beer-Lambert law (2) What is the Absorbance for 1 mm & 5 mm? For 1 mm: A = -log T = -log 0.54 = 0.27 For 5 mm, A = εlc A = (5.4 x10 2 Lmol -1 mm -1 )(5 mm)(5.0 x 10-4 mol L -1 ) = 1.35 ε ε = ( moll ) x (1 mm ) = Lmol mm, or ε = log , Lmol cm Step 3, put in values. Simple equation, always check the units Defined wavelength 20 Page 5
6 21 Limitations of Beer-Lambert law Works with relatively dilute solutions Does not work with turbid samples Need to avoid scattering Fixed single wavelength / fixed temperature Most commonly used with UV-Visible absorption spectroscopy. Can be used with FT-IR etc. 22 2Y Spectroscopy: Topic 3 Electronic Spectroscopy: UV-Visible absorption. Franck-Condon Principle. Fluorescence. Phosphorescence. Stokes shift, Lifetimes, Quantum yield. Understand and be able to explain the different spectroscopies. Chapter 20, Elements of Physical Chemistry Sections 20.1, 20.3, 20.4, and 29.5 Visible spectrum Absorption spectrum 23 Complementary colours opposite ---- Numbers = nm (wavelength) Absorb Red looks Green Absorbs blue looks orange Useful rule of thumb, but not accurate enough for scientific purposes Observer dependant Absorption spectrum of chlorophyll in the visible region. Absorbs in the red and blue regions, green light is not absorbed. 24 Page 6
7 UV-Vis absorption 190 to 1000 nm Organic Chromophores absorb in UV/Vis/NIR C=C, C=O, C=N E = E E = hν ( photon) 2 1 Franck-Condon Principle Nuclei are much more massive than electrons, so Electronic transitions take place faster than nuclei can respond. most intense vibronic transition is from the ground vibrational state to the vibrational state lying vertically above it. Transitions to other vibrational levels also occur, but with lower intensity Absorption in gaseous state The electronic spectra of some molecules show significant vibrational structure. Absorption in solution Very broad, ill defined UV spectrum of gaseous SO 2 at 298 K. Sharp lines in this spectrum are due to transitions from a lower electronic state to different vibrational levels of a higher electronic state Page 7
8 Fluorescence Jablonski diagram Excitation of electron from ground to excited state S 0 to S 1 (or S 2 ) Vibrational Relaxation Emission of a photon of light S 1 to S 0 Phosphorescence Sometimes electron can cross over to triplet level (not allowed transition) Takes much longer for T 1 to S 0, not allowed. Triplet state..2 parallel electron spins ( ) Singlet paired spins ( ) Fluorescence Spectrometer Single channel Right angle excitation nm usually Quartz cuvettes Light source; lamps, LED, laser, Excite with a narrow band Photoluminescence Bioluminescence Chemiluminescence Fluorescence spectra Most spectra don t have features..energy gaps between vibrational levels is too small and if in condensed phase (liquid/solid) they overlap. Not seen at r.t. but if cooled down to LN2 temps can be observed Page 8
9 Stokes Shift Fluorescence Lifetime Born in Sligo longer wavelength than absorption Difference = Stokes Shift Sensitive to environment polarity Ion concentration Average time a molecule spends in the excited state: Nanosecond (10-9 s) to Picosecond (10-12 ) range Anthracene = 5.2 ns in cyclohexane solution For T 1 to S 0 transition lifetime can be seconds Quantum yield (Q) Measure of the efficiency with which absorbed light produces an effect: Ratio of No. of photons emitted to the No. of photons absorbed Good fluorophores have Q close to 1 Q ~ 0, means no fluorescence (or phosphorescence) Tricky to measure experimentally: Have to integrate the absorption and emission bands 36 2Y Spectroscopy: Topic 4 Vibrational Spectroscopy: Vibrations of molecules (stretching, bending, etc,) Selection rules. FT-IR absorption spectroscopy. Raman spectroscopy. Know the key concepts underlying vibrational spectroscopy, and the differences between Raman and IR absorption spectroscopy. Chapter 19, Elements of Physical Chemistry, Sections and Page 9
10 37 Concepts Wavenumber: 5000 nm = 5 x10-4 cm = 2000 cm -1 Molecules have bonds they can vibrate Some bonds are stronger than others: C C / C=C / C-C. Electronegativities..some atoms like electrons more than others. Stronger / weaker bonds. H + F - C-H Ionic..Covalent character. 38 Dipole Moment two electric charges (or partial charges) +q and q separated by a distance R For IR, the atoms can be Slightly different Carbon & Oxygen Nitrogen & Oxygen 39 Molecular Potential Energy Diagram Plot of energy versus internuclear distance: Minimum = equilibrium bond distance (R e ) 0 = dissociation, atoms far apart. MPE diagram For 2 different diatomics. Strong bond Weak bond 40 Molecular vibrations 1 All molecules capable of vibrating. Many different types of vibration (modes): Stretching, Bending, Wagging, Twisting The bigger the molecule, the more vib. modes Diatomics (1 mode) Proteins 10 s of thousands Vibrations excited by absorption of EM radiation of the right energy. Page 10
11 Molecular vibrations 2 Observing the frequencies of vibration can be used to ID molecules: Molecular Fingerprints. FT-IR and Raman spectroscopy used in this way for: Intensity(arb. units) Forensics (drugs, explosives, hazmat) Monitoring progress of reactions Heroin MDMA Cocaine Selection Rules Very important in vibrational spectroscopy. Used to predict which vibrations you should see. Rules are different for IR-Absorption and Raman scattering. Sometimes we see bands in IR and not in Raman..and visa-versa. Raman good for non-polar molecules. IR good for polar molecules Raman shift, cm IR-absorption spectroscopy Light absorbed by molecule: passes light through the sample Measure how much absorbed. Vibrational transitions (lowish energy) IR radiation (2 µm 1000 µm) (5000 cm -1 to 10 cm -1 ) Spectra from ~ cm -1 to 4000 cm -1 Obeys Beer-Lambert (linear with conc.) IR spectrometer Dispersive, like UV-visible, Light passes thru.scan across different wavelengths to make spectrum. Most modern IR spectrometers are Fourier-Transform (FT) based and use a Michelson Interferometer. All light frequencies at once. Faster than scanning Page 11
12 Typical IR spectrum Plot of % Transmittance Versus Wavenumber Vibration type C H C H V/cm C C stretch, bend C=C stretch C C stretch O H stretch C=O stretch C N stretch N H stretch Hydrogen bonds Raman spectroscopy (I) Light interacts with vibrational modes of molecule. A very small amount is scattered at longer/shorter wavelength. Photon hν 0 Stokes Virtual State ν = 4 ν = 3 ν = 2 ν = 1 ν = 0 Photon h(ν ν ) 0 1 Photon hν 0 anti-stokes Virtual State Photon h(ν +ν ) 0 1 ν = 4 ν = 3 ν = 2 ν = 1 ν = 0 Stokes shift to longer wavelength Anti-Stokes to shorter wavelength Electronic Ground State 47 Raman spectroscopy (II) RAMAN (STOKES) RAYLEIGH RAMAN (ANTI-STOKES) (υ 0 υ 1) υ 0 (υ 0 + υ 1) Frequency, cm -1 Stokes lines:- ~10 3 times weaker than Rayleigh scattering - shorter wavelength, gain of energy : Anti-Stokes lines:- ~ weaker than Stokes at ambient temps. Vibrational spectrum similar to an IR spectrum, Based on chemical structure of molecules, Spectra are unique.molecular fingerprints, 48 Raman spectroscopy (III) IR A b s o rp tio n b a n d s R a y le ig h s c a tte rin g R a m a n s a c tte rin g b a n d s Raman looks at the scattered light relative to the excitation line. Can use any wavelength excitation. P h o to n E n e rg y c m , / c m n m H e N e 1 8, / c m n m 2 0, / c m n m A r io n Page 12
13 Raman spectrometer Typical Raman Spectra Pure Cocaine taken using a Battery operated portable system Cocaine hydrochloride, pure. A11AUG13:11/8/ Pure Cocaine taken using a Laboratory system INTENSITY (arb.) Raman shift, cm -1. Gross selection rule: IR-Absorption Changing dipole moment The dipole moment, p, of the molecule must change during the vibration for it to IR active. 51 Does not have to have a permanent dipole can move Some vibrations cause no change in dipole moment (homonuclear diatomics) Transitions are restricted to single-quantum jumps to neighboring levels e.g. from v=0 to v=1, from v=1 to v=2, etc 52 Original molecule AB; 2 atoms + bond electron cloud. Draw bond dipole. Distort molecule. Draw new bond dipole. Has dipole changed? A r r +q -q p r +q -q p B Page 13
14 Gross selection rule: Raman spectroscopy Has to be a change in the polarizability for a vibration to be Raman active: CO 2 symmetric Stretch O C O O C O O C O Distortion of the electron cloud of a molecular entity by a vibration. Good for Homonuclear diatomics (N 2, O 2 etc.) Exclusion Rule: More exact treatment of IR and Raman activity of normal modes leads to the exclusion rule: If the molecule has a centre of symmetry (like CO 2 ), then no modes can be both infrared and Raman active: A mode may be inactive in both. often possible to judge intuitively if a mode changes the molecular dipole moment, use this rule to identify modes that are not Raman active Group theory is used to predict whether a mode is infrared or Raman active (3 rd year) IR vs. Raman spectra FT-IR. Raman.. Raman vs. IR spectroscopy How do the 2 different vibrational techniques compare? How do the selection rules work in practice for polyatomic molecules? What are the advantages/disadvantages? How can we use the techniques for advanced studies? Page 14
15 O-H stretch Ethanol (C 2 H 5 OH) O-H bend Scales not exact match Polar groups give strong IR bands.weaker in Raman Different selection rules Weak O-H bands mean can use OH containing solvents Applications in Microscopy Can use IR and Raman in microscopy. IR radiation = long wavelength = large spot size In practice spot ~10 µm. UV-Vis = shorter wavelength = smaller spot size For 488 nm excitation, spot < 1 µm. Water is a weak Raman scatterer: Can use Raman for analysis of cells & tissue. 57 Data from: ww.aist.go.jp/riodb/sdbs 58 IR versus Raman: comparison IR-absorption Raman Selection rule Change in Dipole moment Change in polarizability Good for Polar molecules (e.g. HCl) Non-polar molecules (e.g. N 2 ) Water Very strong absorption Very weak scattering Wavelength IR region of spectrum Any region Spectra Same ( cm -1 ) Same ( cm -1 ) Sensitivity Good Very weak Y Spectroscopy: Topic 5 Vibrational Energies: Spring Model. Force Constants. Effective mass. Vibrational Energy levels. Effect of bond strength on vibrational transitions. Understand the simple spring model. Be able to calculate force constants & energies of vibrational transitions. Chapter 19, Elements of Physical Chemistry, Sections and Page 15
16 H3C CH3 2 year Spectroscopy Handout: Modelling vibrations Close to R e the MPE curve.approximates to a parabola (y=x 2 ). Potential Energy (V) can be written: V = ½k(R-R e ) 2 Force Constant K Measure of the strength of the bond Parabola gets steeper as k increases. k = force constant (Nm -1 ) Diatomic Model: Both atoms move in a vibration.. Need to use detailed calculations: Schrödinger wave equation (3 rd year) υ = vibrational quantum number. Specific selection rule: υ = ±1 m 1 m 2 K 1 k ν =, µ = effective mass 2π µ (frequency in H z) E = ( υ +½)h ν, υ = 0,1,2,... v Vibrational Energy Levels: E υ ( 1 h k = υ + ), 2 2 π µ (Energy in Joules) 64 Effective Mass (µ) mamb µ =, m + m A B M A M B Na Na µ = in kg, M A M B + Na Na N = avogadros number M a = Atomic mass (in kg) Important for calculating vibrational energies Always a very small number: Page 16
17 65 Vibrational energy levels (diatomics) E (7/2)(h/2π) (k/µ) (5/2)(h/2π) (k/µ) (3/2)(h/2π) (k/µ) (1/2)(h/2π) (k/µ) Differences? Constant E = (h/2π) (k/µ) For photon Therefore 66 Calculating the wavenumber of a vibration An 1 H 35 Cl molecule has a force constant of 516 Nm 1. Calculate the vibrational stretching frequency: The wavenumber of a vibration can be calculated from the equation: 1 k 1 ν =, where ν is the vibrational wavenumber in m. 2π c µ mh mcl Step 1: Calculate the effective mass, µ =, m + m Na µ = Na in kg, Na = avogadros number Na Na µ = kg [ Always write this out longhand] H Cl 67 Calculating the wavenumber of a vibration The wavenumber of a vibr ation can be calculated from the equation: 1 k -1 ν =, whereν is the vibrational wavenumber in m. 2π c µ Step 2: input the values: 1 Nm ν = 2π ms (516 ) (516 kgms m ) , ν = ms ν = ms s kg , 2,[N = kgms ] kg ν = 299, 246 m = 2992 cm Calculating a force constant (step 1) 1 H 35 Cl has a fundamental stretching vibration at 2991 cm -1, Calculate the force constant. The force constant can be calculated from the equation: 1 k -1 ν =, where ν is the vibrational wavenumber in m. 2π c µ Step 1: Rearrange the equation: 1 k 1 k ν = = 2π c µ 4π c µ 4 c = k ν π µ k = 4 ( π c ) , ν, then: 2 2 ν µ Page 17
18 k = 4 Calculating a force constant (step 2) ( c ) π 2 2 ν 2 µ...remember mh mcl Step 2: Calculate the effective mass, µ =, m + m Na Na µ = in kg, Na = avogadros number Na Na µ = x kg [Always write this out longhand ] H Cl Calculating a force constant (step 3) ( c) ( c) k = 2 π ν µ... µ = 1.63 x 10 Step 3: Input values, [ Always write this out longhand] 2 2 k = 2π ν µ = (2π 2.9 = (3.54 kg ms ) (299,100 m ) ( kg) m s )( m )( kg) 2 2 = (517 kgs ) [1 Newton = 1 kgms ] = 517 Nm H 2 + Diatomic Molecules: V/cm 1 R e/pm k/(n m 1 ) D/(kJ mol 1 ) H H H 19 F H 35 Cl H 81 Br H 127 I N 2 235S O F Cl Y Spectroscopy: Topic 6 Polyatomic Molecules: Mass effect. Number of vibrational modes. Anharmonicity. Predicting active modes. Analysis of vibrational spectra. Comparison between Raman and IR spectra. Understand mass effect and factors that influence spectra of polyatomic molecules. Be able to calculate the number of vibrational modes, & predict which bands are IR or Raman active. Chapter 19, Elements of Physical Chemistry, Sections 19.12/13/15 71 p. 497, Atkins & DePaula, 4 th edition. 1 k ν = 2π c µ 72 Page 18
19 73 Polyatomic molecules..n>2 IR spectra are much more complex More than just stretching vibrations: Bending, wagging, twisting Combinations of vibrations 74 Polyatomics? N> Bond ν (cm ) Bond Energy (kjmol ) RC O R 2C = O R C-OR View polyatomic as collection of diatomics Force constants as per diatomics Correlates with bond strength (right-hand column) Mass effect? Yes, next ovhd. Group frequencies or wavenumbers, i.e., all ketones have IR band/peak near 1800 cm 1 Mass effect: CHCl 3 & CDCl 3 Compare CHCl 3 & CDCl 3 1 k 1 ν =, so ν = 2π c µ µ Step 1: Calculate the effective masses, µ µ µ µ H CCl3 H CCl3 D CCl3 D CCl3 75 ( )( ) (.001) + ( ) = in kg, Na = avogadros number N 1 = 1.65 x 10 kg, so... = µ = (.002)( ) (.002) + ( ) 3 Ratio = = a 35 1 N H CCl3 1 = x 10 kg, so... = µ H-CCl D-CCl a D CCl3 Is this seen experimentally? Peak at ~ 3,019 cm 1 due to C H stretch Shifted to ~ 2,258 cm 1 for D C stretch Ratio 3019/2300 = 1.34 (1.406 not bad.) 76 Page 19
20 How many vibrational modes? Rule: The number of modes of vibration N vib : 3N 5 for linear molecules (e.g. CO 2 ) 3N 6 for nonlinear molecules (e.g. H 2 O). 3n degrees of freedom (x, y, z) different displacements Take away the translational (change in x=y=z) so -3 2 angles needed to specify linear molecules orientation (A) 3 angles needed to specify linear molecules orientation (B) Where N = number of atoms in molecule The bigger the molecule the more vibrations If Linear H 2 O: Number of IR bands? Linear triatomic water How many vibrations? 3N-5 = = 4 Can only find three different: Symmetric stretch Asymmetric stretch 2 Bends (identical) Only two are IR active: Changes in dipole moment. H O H H O H H O H Symmetric stretch Asymmetric stretch Bend But we see three experimentally!! Page 20
21 Vibrational modes for bent H 2 O How many vibrations for non-linear molecule? 3N = 3 vibrations Sketch each mode & draw bond dipoles Sum to produce overall dipole Distort molecule for each vibration Redraw bond dipoles Sum to give overall dipole Has dipole changed during vibration? IR Spectra of simple cyanides Linear arrangement of atoms X-C-N 3N-5 vibrations; 3 different & all active Emergent Concept; Group frequencies X C C N B e n d HCN D CN FCN ClCN BrCN ICN HCN Vibrational modes H C N H C N H C N H C N H C stretch H C N H C N C-N stretch H-C stretch H-C-N bends All IR active Isotopic substitution? Identical structure D replacing H No change -8% Big change -20% Some change -20% 84 Band areas Functional group region O-H C-H Single bonds to H Fingerprint region Phenol Page 21
22 Analysis of vibrational spectra (I) Functional group region most important for interpreting IR spectra. In IR it is the polar covalent bonds than are IR "active In Raman spectra non-polar bonds are also active. In organic molecules these polar covalent bonds represent the functional groups. Hence, the most useful information obtained from an IR spectrum is what functional groups are present within the molecule. Analysis of vibrational spectra (II) Some functional groups are combinations of different bond types. Esters (CO 2 R) contain both C=O and C-O bonds, Both are typically seen in an IR spectrum of an ester. In the fingerprint region, spectra tend to be more complex and much harder to assign. But very important in Physics, Materials Science, etc.properties of materials Now some examples: Benzene vs Toluene, liquid CH 3 Environmental Influences (I) Covalent diatomic molecule H Cl Gas-phase 2,886 cm 1 Solid state 2,720 cm 1 Solution (aromatic solvent) 2,712 cm 1 Solution (ether solvent) 2,393 cm 1 Conclusion? NB: wavenumber of absorption (force constant) weak intermolecular bonding R 2 O... H Cl 87 Spectra from: 88 Page 22
23 Environmental Influences (II) Vibrational bands are usually broader in condensed media (solid liquid) than gas phase. Crystalline materials have sharper vibrational bands than amorphous materials. Can be used to distinguish polymorphs of pharmaceutical products 89 Page 23
CHEM 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 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 informationApplication of IR Raman Spectroscopy
Application of IR Raman Spectroscopy 3 IR regions Structure and Functional Group Absorption IR Reflection IR Photoacoustic IR IR Emission Micro 10-1 Mid-IR Mid-IR absorption Samples Placed in cell (salt)
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 informationChapter 17: Fundamentals of Spectrophotometry
Chapter 17: Fundamentals of Spectrophotometry Spectroscopy: the science that deals with interactions of matter with electromagnetic radiation or other forms energy acoustic waves, beams of particles such
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 informationLecture 3: Light absorbance
Lecture 3: Light absorbance Perturbation Response 1 Light in Chemistry Light Response 0-3 Absorbance spectrum of benzene 2 Absorption Visible Light in Chemistry S 2 S 1 Fluorescence http://www.microscopyu.com
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 informationChapter 17: Fundamentals of Spectrophotometry
Chapter 17: Fundamentals of Spectrophotometry Spectroscopy: the science that deals with interactions of matter with electromagnetic radiation or other forms energy acoustic waves, beams of particles such
More informationSpectroscopy. Page 1 of 8 L.Pillay (2012)
Spectroscopy Electromagnetic radiation is widely used in analytical chemistry. The identification and quantification of samples using electromagnetic radiation (light) is called spectroscopy. Light has
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 informationInfrared 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 informationtwo slits and 5 slits
Electronic Spectroscopy 2015January19 1 1. UV-vis spectrometer 1.1. Grating spectrometer 1.2. Single slit: 1.2.1. I diffracted intensity at relative to un-diffracted beam 1.2.2. I - intensity of light
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 informationRadiant energy is proportional to its frequency (cycles/s = Hz) as a wave (Amplitude is its height) Different types are classified by frequency or
CHEM 241 UNIT 5: PART B INFRA-RED RED SPECTROSCOPY 1 Spectroscopy of the Electromagnetic Spectrum Radiant energy is proportional to its frequency (cycles/s = Hz) as a wave (Amplitude is its height) Different
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 informationCHAPTER 13 Molecular Spectroscopy 2: Electronic Transitions
CHAPTER 13 Molecular Spectroscopy 2: Electronic Transitions I. General Features of Electronic spectroscopy. A. Visible and ultraviolet photons excite electronic state transitions. ε photon = 120 to 1200
More information7a. Structure Elucidation: IR and 13 C-NMR Spectroscopies (text , , 12.10)
2009, Department of Chemistry, The University of Western Ontario 7a.1 7a. Structure Elucidation: IR and 13 C-NMR Spectroscopies (text 11.1 11.5, 12.1 12.5, 12.10) A. Electromagnetic Radiation Energy is
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 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 informationChemistry Instrumental Analysis Lecture 3. Chem 4631
Chemistry 4631 Instrumental Analysis Lecture 3 Quantum Transitions The energy of a photon can also be transferred to an elementary particle by adsorption if the energy of the photon exactly matches the
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 informationSkoog Chapter 6 Introduction to Spectrometric Methods
Skoog Chapter 6 Introduction to Spectrometric Methods General Properties of Electromagnetic Radiation (EM) Wave Properties of EM Quantum Mechanical Properties of EM Quantitative Aspects of Spectrochemical
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 informationMolecular spectroscopy
Molecular spectroscopy Origin of spectral lines = absorption, emission and scattering of a photon when the energy of a molecule changes: rad( ) M M * rad( ' ) ' v' 0 0 absorption( ) emission ( ) scattering
More information/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 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 informationwhere, c is the speed of light, ν is the frequency in wave numbers (cm -1 ) and µ is the reduced mass (in amu) of A and B given by the equation: ma
Vibrational Spectroscopy A rough definition of spectroscopy is the study of the interaction of matter with energy (radiation in the electromagnetic spectrum). A molecular vibration is a periodic distortion
More informationInfrared spectroscopy Basic theory
Infrared spectroscopy Basic theory Dr. Davide Ferri Paul Scherrer Institut 056 310 27 81 davide.ferri@psi.ch Importance of IR spectroscopy in catalysis IR Raman NMR XAFS UV-Vis EPR 0 200 400 600 800 1000
More informationInfrared 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 information24 Introduction to Spectrochemical Methods
24 Introduction to Spectrochemical Methods Spectroscopic method: based on measurement of the electromagnetic radiation produced or absorbed by analytes. electromagnetic radiation: include γ-ray, X-ray,
More informationUV-vis (Electronic) Spectra Ch.13 Atkins, Ch.19 Engel
XV 74 UV-vis (Electronic) Spectra-2014 -Ch.13 Atkins, Ch.19 Engel Most broadly used analytical tech / especially bio-applic. inexpensive optics / solvent & cell usually not problem intense transitions
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 informationUV / Visible Spectroscopy. Click icon to add picture
UV / Visible Spectroscopy Click icon to add picture Spectroscopy It is the branch of science that deals with the study of interaction of matter with light. OR It is the branch of science that deals with
More informationI 2 Vapor Absorption Experiment and Determination of Bond Dissociation Energy.
I 2 Vapor Absorption Experiment and Determination of Bond Dissociation Energy. What determines the UV-Vis (i.e., electronic transitions) band appearance? Usually described by HOMO LUMO electron jump LUMO
More informationSpectroscopy: Tinoco Chapter 10 (but vibration, Ch.9)
Spectroscopy: Tinoco Chapter 10 (but vibration, Ch.9) XIV 67 Vibrational Spectroscopy (Typical for IR and Raman) Born-Oppenheimer separate electron-nuclear motion ψ (rr) = χ υ (R) φ el (r,r) -- product
More informationInfrared 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 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 XIV 67 Born-Oppenheimer approx. separate electron-nuclear Assume elect-nuclear motion separate,
More informationRb, which had been compressed to a density of 1013
Modern Physics Study Questions for the Spring 2018 Departmental Exam December 3, 2017 1. An electron is initially at rest in a uniform electric field E in the negative y direction and a uniform magnetic
More informationRaman and stimulated Raman spectroscopy of chlorinated hydrocarbons
Department of Chemistry Physical Chemistry Göteborg University KEN140 Spektroskopi Raman and stimulated Raman spectroscopy of chlorinated hydrocarbons WARNING! The laser gives a pulsed very energetic and
More informationvan Quantum tot Molecuul
10 HC10: Molecular and vibrational spectroscopy van Quantum tot Molecuul Dr Juan Rojo VU Amsterdam and Nikhef Theory Group http://www.juanrojo.com/ j.rojo@vu.nl Molecular and Vibrational Spectroscopy Based
More informationStructure 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 informationR O Y G B V. Spin States. Outer Shell Electrons. Molecular Rotations. Inner Shell Electrons. Molecular Vibrations. Nuclear Transitions
Spin States Molecular Rotations Molecular Vibrations Outer Shell Electrons Inner Shell Electrons Nuclear Transitions NMR EPR Microwave Absorption Spectroscopy Infrared Absorption Spectroscopy UV-vis Absorption,
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 informationWilliam H. Brown & Christopher S. Foote
Requests for permission to make copies of any part of the work should be mailed to:permissions Department, Harcourt Brace & Company, 6277 Sea Harbor Drive, Orlando, Florida 32887-6777 William H. Brown
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 informationChem Homework Set Answers
Chem 310 th 4 Homework Set Answers 1. Cyclohexanone has a strong infrared absorption peak at a wavelength of 5.86 µm. (a) Convert the wavelength to wavenumber.!6!1 8* = 1/8 = (1/5.86 µm)(1 µm/10 m)(1 m/100
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 informationIntroduction. The analysis of the outcome of a reaction requires that we know the full structure of the products as well as the reactants
Introduction The analysis of the outcome of a reaction requires that we know the full structure of the products as well as the reactants Spectroscopy and the Electromagnetic Spectrum Unlike mass spectrometry,
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 informationUltraviolet-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 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 informationI 2 Vapor Absorption Experiment and Determination of Bond Dissociation Energy.
I 2 Vapor Absorption Experiment and Determination of Bond Dissociation Energy. What determines the UV-Vis (i.e., electronic transitions) band appearance? Usually described by HOMO LUMO electron jump LUMO
More informationChemistry 2. Molecular Photophysics
Chemistry 2 Lecture 12 Molecular Photophysics Assumed knowledge Electronic states are labelled using their spin multiplicity with singlets having all electron spins paired and triplets having two unpaired
More informationReflection = EM strikes a boundary between two media differing in η and bounces back
Reflection = EM strikes a boundary between two media differing in η and bounces back Incident ray θ 1 θ 2 Reflected ray Medium 1 (air) η = 1.00 Medium 2 (glass) η = 1.50 Specular reflection = situation
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 informationChapter 4 Ultraviolet and visible spectroscopy Molecular Spectrophotometry
Chapter 4 Ultraviolet and visible spectroscopy Molecular Spectrophotometry Properties of light Electromagnetic radiation and electromagnetic spectrum Absorption of light Beer s law Limitation of Beer s
More informationLecture 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 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 informationWavelength λ Velocity v. Electric Field Strength Amplitude A. Time t or Distance x time for 1 λ to pass fixed point. # of λ passing per s ν= 1 p
Introduction to Spectroscopy (Chapter 6) Electromagnetic radiation (wave) description: Wavelength λ Velocity v Electric Field Strength 0 Amplitude A Time t or Distance x Period p Frequency ν time for 1
More informationChem 321 Lecture 18 - Spectrophotometry 10/31/13
Student Learning Objectives Chem 321 Lecture 18 - Spectrophotometry 10/31/13 In the lab you will use spectrophotometric techniques to determine the amount of iron, calcium and magnesium in unknowns. Although
More informationChapter 6 Photoluminescence Spectroscopy
Chapter 6 Photoluminescence Spectroscopy Course Code: SSCP 4473 Course Name: Spectroscopy & Materials Analysis Sib Krishna Ghoshal (PhD) Advanced Optical Materials Research Group Physics Department, Faculty
More informationMOLECULAR 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 informationOptical Spectroscopy 1 1. Absorption spectroscopy (UV/vis)
Optical Spectroscopy 1 1. Absorption spectroscopy (UV/vis) 2 2. Circular dichroism (optical activity) CD / ORD 3 3. Fluorescence spectroscopy and energy transfer Electromagnetic Spectrum Electronic Molecular
More informationSpectral 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 informationVibrational Spectroscopies. C-874 University of Delaware
Vibrational Spectroscopies C-874 University of Delaware Vibrational Spectroscopies..everything that living things do can be understood in terms of the jigglings and wigglings of atoms.. R. P. Feymann Vibrational
More informationCHEM*3440. Photon Energy Units. Spectrum of Electromagnetic Radiation. Chemical Instrumentation. Spectroscopic Experimental Concept.
Spectrum of Electromagnetic Radiation Electromagnetic radiation is light. Different energy light interacts with different motions in molecules. CHEM*344 Chemical Instrumentation Topic 7 Spectrometry Radiofrequency
More informationPHOTOCHEMISTRY NOTES - 1 -
- 1 - PHOTOCHEMISTRY NOTES 1 st Law (Grotthus-Draper Law) Only absorbed radiation produces chemical change. Exception inelastic scattering of X- or γ-rays (electronic Raman effect). 2 nd Law (Star-Einstein
More informationLecture 11. IR Theory. Next Class: Lecture Problem 4 due Thin-Layer Chromatography
Lecture 11 IR Theory Next Class: Lecture Problem 4 due Thin-Layer Chromatography This Week In Lab: Ch 6: Procedures 2 & 3 Procedure 4 (outside of lab) Next Week in Lab: Ch 7: PreLab Due Quiz 4 Ch 5 Final
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 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 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 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 informationClassification of spectroscopic methods
Introduction Spectroscopy is the study of the interaction between the electromagnetic radiation and the matter. Spectrophotometry is the measurement of these interactions i.e. the measurement of the intensity
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 information12. Structure Determination: Mass Spectrometry and Infrared Spectroscopy
12. Structure Determination: Mass Spectrometry and Infrared Spectroscopy Determining the Structure of an Organic Compound The analysis of the outcome of a reaction requires that we know the full structure
More informationHomework Due by 5PM September 20 (next class) Does everyone have a topic that has been approved by the faculty?
Howdy Folks. Homework Due by 5PM September 20 (next class) 5-Problems Every Week due 1 week later. Does everyone have a topic that has been approved by the faculty? Practice your presentation as I will
More informationAssumed knowledge. Chemistry 2. Learning outcomes. Electronic spectroscopy of polyatomic molecules. Franck-Condon Principle (reprise)
Chemistry 2 Lecture 11 Electronic spectroscopy of polyatomic molecules Assumed knowledge For bound excited states, transitions to the individual vibrational levels of the excited state are observed with
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 informationUnit 11 Instrumentation. Mass, Infrared and NMR Spectroscopy
Unit 11 Instrumentation Mass, Infrared and NMR Spectroscopy Spectroscopic identification of organic compounds Qualitative analysis: presence but not quantity (i.e. PEDs) Quantitative analysis: quantity
More informationLABORATORY OF ELEMENTARY BIOPHYSICS
LABORATORY OF ELEMENTARY BIOPHYSICS Experimental exercises for III year of the First cycle studies Field: Applications of physics in biology and medicine Specialization: Molecular Biophysics Fluorescence
More informationTypes of Molecular Vibrations
Important concepts in IR spectroscopy Vibrations that result in change of dipole moment give rise to IR absorptions. The oscillating electric field of the radiation couples with the molecular vibration
More informationChemistry 213 Practical Spectroscopy
Chemistry 213 Practical Spectroscopy Dave Berg djberg@uvic.ca Elliott 314 A course in determining structure by spectroscopic methods Different types of spectroscopy afford different information about molecules
More informationSPECTROSCOPY 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 informationUltraviolet-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 informationWhat dictates the rate of radiative or nonradiative excited state decay?
What dictates the rate of radiative or nonradiative excited state decay? Transitions are faster when there is minimum quantum mechanical reorganization of wavefunctions. This reorganization energy includes
More informationA very brief history of the study of light
1. Sir Isaac Newton 1672: A very brief history of the study of light Showed that the component colors of the visible portion of white light can be separated through a prism, which acts to bend the light
More informationQuímica Orgânica I. Ciências Farmacêuticas Bioquímica Química. IR spectroscopy AFB QO I 2007/08 1 AFB QO I 2007/08 2
Química Orgânica I Ciências Farmacêuticas Bioquímica Química AFB QO I 2007/08 1 IR spectroscopy AFB QO I 2007/08 2 1 Adaptado de: Organic Chemistry, 6th Edition; L. G. Wade, Jr. Organic Chemistry, William
More informationAdvanced Spectroscopy Laboratory
Advanced Spectroscopy Laboratory - Raman Spectroscopy - Emission Spectroscopy - Absorption Spectroscopy - Raman Microscopy - Hyperspectral Imaging Spectroscopy FERGIELAB TM Raman Spectroscopy Absorption
More informationUltraviolet-Visible Spectroscopy
Ultraviolet-Visible Spectroscopy Introduction to UV-Visible Absorption spectroscopy from 160 nm to 780 nm Measurement of transmittance Conversion to absorbance * A=-logT=εbc Measurement of transmittance
More informationLectures Spectroscopy. Fall 2012
Lectures 19-20 Spectroscopy Fall 2012 1 spectroscopic principles (Chem 1M/1N exps. #6 and #11) 4 spectroscopic excitations ( E = h = hc/ ; = c ) (nm) (sec -1 ) radiation technique molecular excitation
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 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 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 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 informationBecause light behaves like a wave, we can describe it in one of two ways by its wavelength or by its frequency.
Light We can use different terms to describe light: Color Wavelength Frequency Light is composed of electromagnetic waves that travel through some medium. The properties of the medium determine how light
More informationCD Basis Set of Spectra that is used is that derived from comparing the spectra of globular proteins whose secondary structures are known from X-ray
CD Basis Set of Spectra that is used is that derived from comparing the spectra of globular proteins whose secondary structures are known from X-ray crystallography An example of the use of CD Modeling
More informationWhat is spectroscopy?
Absorption Spectrum What is spectroscopy? Studying the properties of matter through its interaction with different frequency components of the electromagnetic spectrum. With light, you aren t looking directly
More informationPhotochemical principles
Chapter 1 Photochemical principles Dr. Suzan A. Khayyat 1 Photochemistry Photochemistry is concerned with the absorption, excitation and emission of photons by atoms, atomic ions, molecules, molecular
More information