Interpretation:
Six of the nine vibrational degrees of freedom of
Concept Introduction:
Raman and infrared (IR) spectroscopies are branches of vibrational spectroscopy.
For a mode of vibration to be infrared (IR) active, it must give rise to a change in the molecular electric dipole moment.
For a mode of vibration to be Raman active, it must give rise to a change in the polarizability of the molecule.
Vibrational spectroscopy is concerned with the observation and determination of number of the degrees of vibrational freedom.
The degrees of vibrational freedom depends on the number of atoms in molecule and shape of the molecule.
The number and nature of the symmetry elements of a given molecule are conveniently represented by its point groups and give rise to labels such as
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Inorganic Chemistry
- Vibrational wavenumbers for K[N3] are 2041, 1344 and 645 cm-1. Draw the structure of the [N3]- ion and sketch the 3 vibrational modes. Which are IR active?arrow_forwardProve that ICl3 occurs in the bent-T shaped structure predicted by VSEPR and not in a trigonal planar structure by determining the number and symmetries of the vibrations of each shape and how many are IR and Raman active. Given that ICl3 has 6 active vibrations in both IR and Raman spectroscopy, which shape is correct?arrow_forward1.Explain out plane and Asymmetrical vibration 2.Explain the principle of operation of UV-Spectroscopy 3. Discuss 2 factors that result in deviation from Beer's lawarrow_forward
- 2. What are some of the factors that can make interpreting IR spectra more difficult and that should be considered to avoid band misinterpretation?arrow_forwardThe IR spectrum of HCN shows three strong absorption band at 3312 cm⁻¹, 2089 cm⁻¹ and 712 cm⁻¹ from this information alone can you deduce whether HCN is linear or nonlinear? Assuming that HCN is linear assign vibration to the three absorption bands.arrow_forwardWhat are the different types of Monochromator in IR spectroscopy? Explain each of them? Please explain at your own words.arrow_forward
- Vibrational spectroscopy has played a role in supporting the pentagonal bipyramidal structure of the ion IO2F5 2-. Raman spectroscopy of the tetramethylammonium salt of this ion shows a single absorption in the region expected for I=O stretching vibrations, at 789 cm-1 . Is a single Raman band consistent with the proposed trans orientation of the oxygen atoms?arrow_forwardWhy are the peaks for both the IR and Raman spectra of chloroform at the same frequencies?arrow_forwardSuggest a reason why the spin-lattice relaxation time of benzene (a small molecule) in a mobile, deuterated hydrocarbon solvent increases whereas that of a polymer decreases.arrow_forward
- Functional groups such as anhydride, carboxylate (but not carboxylic acid), nitro, primary amino give two stretching vibrational bands in the infrared spectrum. What is the origin of these two bands ?arrow_forwardThe NH bobds in ammonia have an IR frequency of 3335 cm^-1, while the PH bonds in phosphine have an IR frequency of 2327 cm^-1. In a single sentence, describe the reason for the difference.arrow_forward1. Suggest 3 applications of Raman spectroscopy. 2. How polarizability is related to electric dipole moment? 3. How does the induced dipole moment occur? 4. Give the general parts of a Raman spectrophotometer. 5. Raman spectroscopy and infrared spectroscopy measures the vibrational frequencies of a molecule. List the differences between these two spectroscopic techniques.arrow_forward
- Principles of Instrumental AnalysisChemistryISBN:9781305577213Author:Douglas A. Skoog, F. James Holler, Stanley R. CrouchPublisher:Cengage LearningOrganic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning