Tutorial on Infrared Spectroscopy and DualBeam Infrared Spectrometer. Prepared by Lawrence Kok http://lawrencekok.blogspot...
Electromagnetic RadiationVelocity of light (c ) = frequency (f) x wavelength (λ)•c=fλ• All electromagnetic waves travel at...
Electromagnetic Radiation and Spectroscopy                Electromagnetic Radiation Interact with Matter (Atoms, Molecules...
IR absorption due to molecular Vibration Polar molecule will absorb IR • H-CI, as bond stretches, distance between atoms  ...
Transmittance or Absorbance of IR Spectra   IR radiation absorbed by molecule is converted into vibrational energy within ...
Transmittance or Absorbance of IR Spectra   IR radiation absorbed by molecule is converted into vibrational energy within ...
Transmittance or Absorbance of IR Spectra   IR radiation absorbed by molecule is converted into vibrational energy within ...
Infrared SpectroscopyInfra Red Spectroscopy• Fingerprinting region (400- 1500)cm-1 – due to vibration of entire molecule, ...
Infrared SpectroscopyInfra Red Spectroscopy• Fingerprinting region (400- 1500)cm-1 – due to vibration of entire molecule, ...
Infrared SpectroscopyInfra Red Spectroscopy• Fingerprinting region (400- 1500)cm-1 – due to vibration of entire molecule, ...
Operating Principle of a Double Beam Infrared Spectrometer Monochromator                                                  ...
IR absorption frequency                                                       Weak bond                                   ...
IR absorption frequency                                                             Weak bond                             ...
IR absorption frequency                                                             Weak bond                             ...
IR Spectroscopy on Alcohol Level Determination  Intoximeter – Measure the alcohol content in breath                       ...
IR Spectroscopy on Alcohol Level Determination                               Intoximeter – Measure the alcohol content in ...
IR spectra of organic compounds with different functional groupsIR Absorption by different types of bonds/functional gpsDi...
IR spectra of organic compounds with different functional groups
IR spectra of organic compounds with different functional groups       Halogenoalkane                                     ...
IR spectra of organic compounds with different functional groupsMethanol (CH3OH)                                          ...
IR Spectra search for different Organic MoleculesClick here to animated Spectra                              Click here to...
AcknowledgementsThanks to source of pictures and video used in this presentationThanks to Creative Commons for excellent c...
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IB Chemistry on Infrared Spectroscopy and IR Spectra analysis

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IB Chemistry on Infrared Spectroscopy and IR Spectra analysis

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Transcript of "IB Chemistry on Infrared Spectroscopy and IR Spectra analysis"

  1. 1. Tutorial on Infrared Spectroscopy and DualBeam Infrared Spectrometer. Prepared by Lawrence Kok http://lawrencekok.blogspot.com
  2. 2. Electromagnetic RadiationVelocity of light (c ) = frequency (f) x wavelength (λ)•c=fλ• All electromagnetic waves travel at the speed of light (3.00 x 108ms-1)• Radiation with high ↑ frequency – short ↓ wavelength• Electromagnetic radiation has a particle nature and each photon carry a quantum of energy given by hc E = hf E Short ↓ λ, Higher ↑ frequency, Higher Energy ↑ h = plank constant = 6.626 x 10-34 Js  c = speed of light = 3.00 x 108ms-1 f = frequency λ = wavelengthPicture from :http://www.azimuthproject.org/azimuth/show/Blog+-+a+quantum+of+warmth
  3. 3. Electromagnetic Radiation and Spectroscopy Electromagnetic Radiation Interact with Matter (Atoms, Molecules) = Spectroscopy Electromagnetic Radiation Radiowaves Infra Red UV or visible Nuclear spin Molecular vibration Transition of outer most valence electrons Nuclear Magnetic Resonance Infra Red Spectroscopy UV Spectroscopy Atomic Absorption Spectroscopy Spectroscopy• Organic structure determination • Organic structure determination • Quantification of metal ions• MRI and body scanning • Functional gp determination • Detection of metal in various samples • Measuring bond strength • Measuring level of alcohol in breath
  4. 4. IR absorption due to molecular Vibration Polar molecule will absorb IR • H-CI, as bond stretches, distance between atoms increases, results in change in dipole moment Change in dipole moment IR frequency is appliedCondition for molecular vibration to absorb a photon /IR• Vibration causing oscillation in developing a change in dipole bet opposite charged centres• Vibration of bond in HCI will cause the dipole in bond to oscillate• Causes a change in dipole momentOscillation of bonds- Lead to oscillation of dipole - lead to change in dipole moment Molecular Vibration Dipole change IR frequency = Natural frequency for bond – Resonance will happenIR frequency = Natural frequency for bond – Resonance will happen.• HCI bond has natural vibrational frequency• IR frequency match the vibrational frequency in HCI, then IR is absorb and Vibrational motion -result in a change dipole moment – IR activemolecule excited to vibrational state• IR absorb by bond will result in greater vibration in amplitude
  5. 5. Transmittance or Absorbance of IR Spectra IR radiation absorbed by molecule is converted into vibrational energy within the molecule. IR frequency match the natural vibrational frequency of molecule , then IR is absorbed and resonance happen (excited vibrational state). Absorption on Y-axis and wavenumber on the X-axis. Absorption plotted two ways. Transmittance, %(T) and Absorbance (A) Transmittance of 100% means IR Absorbance of 0% . Transmittance of 0% means IR Absorbance of 100%IR radiation absorbed Bonds undergo Resonance
  6. 6. Transmittance or Absorbance of IR Spectra IR radiation absorbed by molecule is converted into vibrational energy within the molecule. IR frequency match the natural vibrational frequency of molecule , then IR is absorbed and resonance happen (excited vibrational state). Absorption on Y-axis and wavenumber on the X-axis. Absorption plotted two ways. Transmittance, %(T) and Absorbance (A) Transmittance of 100% means IR Absorbance of 0% . Transmittance of 0% means IR Absorbance of 100%IR radiation absorbed Bonds undergo Resonance Absorbance is High ↑ Absorbance Absorbance is LowClick here to view Wavenumber, cm-1
  7. 7. Transmittance or Absorbance of IR Spectra IR radiation absorbed by molecule is converted into vibrational energy within the molecule. IR frequency match the natural vibrational frequency of molecule , then IR is absorbed and resonance happen (excited vibrational state). Absorption on Y-axis and wavenumber on the X-axis. Absorption plotted two ways. Transmittance, %(T) and Absorbance (A) Transmittance of 100% means IR Absorbance of 0% . Transmittance of 0% means IR Absorbance of 100% Transmittance is 100% Transmittance /% Transmittance is Low ↓IR radiation absorbed Bonds undergo Resonance Wavenumber, cm-1 Absorbance is High ↑ Absorbance Absorbance is LowClick here to view Wavenumber, cm-1
  8. 8. Infrared SpectroscopyInfra Red Spectroscopy• Fingerprinting region (400- 1500)cm-1 – due to vibration of entire molecule, not independent functional gp• IR active – it must have an electric dipole that changes as it vibrates• IR does not have enough energy to excite electrons, only causes molecular vibration• Wavenumber = Reciprocal of wavelength (1/λ) , Unit = cm-1• Wavenumber = 1/ Wavelength = number of waves cycles in one centimeter• Wavenumber α frequency• Wavenumber used in IR spectroscopy• Higher Wavenumber ↑ = Lower wavelength ↓= Higher ↑ frequency = = Greater Energy ↑
  9. 9. Infrared SpectroscopyInfra Red Spectroscopy• Fingerprinting region (400- 1500)cm-1 – due to vibration of entire molecule, not independent functional gp• IR active – it must have an electric dipole that changes as it vibrates• IR does not have enough energy to excite electrons, only causes molecular vibration• Wavenumber = Reciprocal of wavelength (1/λ) , Unit = cm-1• Wavenumber = 1/ Wavelength = number of waves cycles in one centimeter• Wavenumber α frequency• Wavenumber used in IR spectroscopy• Higher Wavenumber ↑ = Lower wavelength ↓= Higher ↑ frequency = = Greater Energy ↑Infrared wavelength from (2500 – 25000)nm → Convert to wavenumber (400– 4000)cm-1Wavenumber between 400cm-1 – 4000cm-1Wavelength, λ = 2500nm (convert to cm) → λ = 0.00025cm → Wavenumber = 1/λ = 1/0.00025 = 4000 cm-1Wavelength, λ = 25000nm (convert to cm) → λ = 0.0025cm → Wavenumber = 1/λ = 1/0.0025 = 400 cm-1 Wavenumber bet 400cm-1 – 4000cm-1 IR absorption by different functional gps Fingerprinting region
  10. 10. Infrared SpectroscopyInfra Red Spectroscopy• Fingerprinting region (400- 1500)cm-1 – due to vibration of entire molecule, not independent functional gp• IR active – it must have an electric dipole that changes as it vibrates• IR does not have enough energy to excite electrons, only causes molecular vibration• Wavenumber = Reciprocal of wavelength (1/λ) , Unit = cm-1• Wavenumber = 1/ Wavelength = number of waves cycles in one centimeter• Wavenumber α frequency• Wavenumber used in IR spectroscopy• Higher Wavenumber ↑ = Lower wavelength ↓= Higher ↑ frequency = = Greater Energy ↑Infrared wavelength from (2500 – 25000)nm → Convert to wavenumber (400– 4000)cm-1Wavenumber between 400cm-1 – 4000cm-1Wavelength, λ = 2500nm (convert to cm) → λ = 0.00025cm → Wavenumber = 1/λ = 1/0.00025 = 4000 cm-1Wavelength, λ = 25000nm (convert to cm) → λ = 0.0025cm → Wavenumber = 1/λ = 1/0.0025 = 400 cm-1 Wavenumber bet 400cm-1 – 4000cm-1 IR absorption by different functional gps Fingerprinting region Wavelength, λ low ↓ → Wavenumber, 1/λ is High ↑ Speed of light, c = fλ, f = c/λ → c x 1/λ Wavenumber, 1/λ is High ↑ → f = c x 1/λ → f is High ↑ (cause 1/λ is high) → Energy = hf High ↑
  11. 11. Operating Principle of a Double Beam Infrared Spectrometer Monochromator Double beam splitter • Allow radiation of a particular wavelength to pass through • Directs half radiation through sample and other half through reference • Allow radiation passing through sample and compare it with reference • Two beams recombined at detector. • Signal from sample/reference are compared to determine if sample absorb radiation emitted from sourceLight Source• Provide IR radiation Reference Recorder/Output • Solvent used to dissolve sample •Scanning wavenumber from 400cm-1 to 4000cm-1 • Reference use to eliminate instrument fluctuation, • Spectrum of Abs/Trans against frequency/wavenumber is produced absorption due to impurities in solvent and all interferences. • Absorption of IR is only due to solute using the reference Fourier transformation • Allow several wavelength through the sample at the same time and analyse the results • Using mathematical techniques to determine the amplitude/intensity of each single frequency • Fourier transformation- Intensity of IR radiation at each frequency determined separately
  12. 12. IR absorption frequency Weak bond Weaker bond Strength of bond • Lower energy needed for resonance Single, Double, Triple Bonds • Lower frequency/wavenumber absorbed Stronger bond Strong bond • Higher energy needed for resonance • Higher frequency/wavenumber absorbedIR absorption frequency depends
  13. 13. IR absorption frequency Weak bond Weaker bond Strength of bond • Lower energy needed for resonance Single, Double, Triple Bonds • Lower frequency/wavenumber absorbed Stronger bond Strong bond • Higher energy needed for resonance • Higher frequency/wavenumber absorbed Lighter/Lower Mass atom • Higher energy frequency for vibration C- H = 2840cm-1IR absorption frequency Mass of atoms depends Heavier/Higher Mass atom C- CI = 600cm-1 • Lower energy/frequency for vibration
  14. 14. IR absorption frequency Weak bond Weaker bond Strength of bond • Lower energy needed for resonance Single, Double, Triple Bonds • Lower frequency/wavenumber absorbed Stronger bond Strong bond • Higher energy needed for resonance • Higher frequency/wavenumber absorbed Lighter/Lower Mass atom • Higher energy frequency for vibration C- H = 2840cm-1IR absorption frequency Mass of atoms depends Heavier/Higher Mass atom C- CI = 600cm-1 • Lower energy/frequency for vibration Stretching Vibration Stretching • More energy needed to stretch bond C- H stretch = 2840cm-1 Vibration • Higher frequency/wavenumber Vs needed Bending Vibration Bending Vibration • Less energy needed for resonance C- H bend = 1400cm-1 • Lower frequency/wavenumber needed
  15. 15. IR Spectroscopy on Alcohol Level Determination Intoximeter – Measure the alcohol content in breath Reference cell Infrared Breath sample out Sample cell Breath sample in Major absorption for alcohol • 3230cm-1 – (O-H) stretch • 2950cm-1 – (C-H) stretch • 1400cm-1 – (C-H) bend • 1200cm-1 – (C-O) stretch
  16. 16. IR Spectroscopy on Alcohol Level Determination Intoximeter – Measure the alcohol content in breath Reference cell Infrared Breath sample out Sample cell Breath sample in Major absorption for alcohol • 3230cm-1 – (O-H) stretch • 2950cm-1 – (C-H) stretch • 1400cm-1 – (C-H) bend • 1200cm-1 – (C-O) stretch• Alcohol concentration cannot be measured from O-H vibration (3230cm-1) due to water vapour present in atmosphere and breath• C-H vibration ( 2950cm-1 ) is used• Propanone, ketone bodies which is produced by diabetic patients also absorb at 2950cm -1• A second sensor to detect propanone was used. (To eliminate the absorption due to propanone)
  17. 17. IR spectra of organic compounds with different functional groupsIR Absorption by different types of bonds/functional gpsDifferent bonds absorb IR radiation at frequency/wavenumber .Use IR to identify the bonds and the functional group in a molecule.Common functional groups• (COOH), (O-H), (C=O), (C=C), (C-O), (C-H) IR spectrum with different functional gps and fingerprint region Fingerprinting region • Range from (1500- 400cm -1) • Specific to each molecule
  18. 18. IR spectra of organic compounds with different functional groups
  19. 19. IR spectra of organic compounds with different functional groups Halogenoalkane Aldehyde Chloromethane CH3CI Propanal (CH3CH2CHO) • (2840-3000) → C-H stretch • (2840-3000) → C-H stretch • (1200-1400) → C-H bend • (2720) → C-H stretch of CHO • (700-800) → C-CI stretch • (1680-1740) → C=O stretch Alkene AlkyneHex-1-ene CH2=CH(CH2)3CH3 Hex-1-yne CH2≡CH(CH2)3CH3• (2840-3000) → C-H stretch • (3350) → C≡ C stretch• (1610-1680) → C-C stretch • (2840-3000) → C-H stretch• (1200- 1400) → C-H bend • (1200- 1400) → C-H bend
  20. 20. IR spectra of organic compounds with different functional groupsMethanol (CH3OH) Ethanol(CH3CH2OH)• (3230-3550) → O-H stretch • (3230-3550) → O-H stretchBroad Absorption due to H bonding between molecules Broad Absorption due to H bonding between molecules• (2840-3000) → C-H stretch • (2840-3000) → C-H stretch• (1000-1300) → C-O stretch • (1000-1300) → C-O stretch • (1200- 1400) → C-H bend Benzoic acid (C6H5COOH) Phenol (C6H5OH) • (3230-3550) → O-H stretch • (3230-3550) → O-H stretch Broad Absorption due to H bonding between molecules Broad Absorption due to H bonding between molecules • (2840-3000) → C-H stretch • (2840-3000) → C-H stretch • (1400-1500) → C=C aromatic stretch • (1400-1500) → C=C aromatic stretch • (1000-1300) → C-O stretch • (1000-1300) → C-O stretch • (1680-1740) → C=O stretch
  21. 21. IR Spectra search for different Organic MoleculesClick here to animated Spectra Click here to search IR spectra
  22. 22. AcknowledgementsThanks to source of pictures and video used in this presentationThanks to Creative Commons for excellent contribution on licenseshttp://creativecommons.org/licenses/Prepared by Lawrence KokCheck out more video tutorials from my site and hope you enjoy this tutorialhttp://lawrencekok.blogspot.com
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