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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI 600 034
M.Sc.DEGREE EXAMINATION PHYSICS
THIRDSEMESTER APRIL 2018
16PPH3MC02/PH3815-SPECTROSCOPY
Date: 26-04-2018 Dept. No. Max. 100 Marks
Time: 09:00-12:00
PART A
Answer ALL questions (10×2=20)
1. Explain microwave active and microwave inactive molecules with an example for each.
2. The bond length of HF molecule is 0.0927 nm. What is the moment of inertia of the HF molecule?
3. How many normal modes of vibration are possible for H2O HCl C6H6
OCS?
4. State the rule of mutual exclusion.
5. What is pre-dissociation?
6. What is the energy of a wave of wavelength 12,500
7. State the advantages of TMS when recording NMR spectra.
8. An NMR signal for a compound is found to be 160 Hz downwards from TMS peak operating at 100 MHz. Calculate its chemical shift in ppm.
9. Write any two applications of SEM.
10. What is fluorescence spectroscopy?
PART B
Answer any FOUR questions (4×7.5=30)
11. Illustrate the effect of isotopic substitution on the pure rotational spectra of a diatomic molecule.
The first rotational line of 12C16O is observed at 3.84235 cm-1 and that of 13C16O at 3.673377 cm-1. Calculate the atomic weight of 13C, assuming the mass of 16O to be 15.9949 amu.
12. Outline briefly each section of an IR spectrometer.
Calculate the frequency of NO molecule whose force constants is 1609 Nm-1.
13. Explain polarizability ellipsoid. On the basis of polarizability, outline the vibrational Raman effect of H2O
The first rotational Raman line of H2 appears at 346 cm-1 from the exciting line. Calculate the bond length of H2 molecule.
14. State Franck-Condon principle andaccount for intensity of spectral lines.
15. Explain the chemical shift in NMR spectroscopy.
16. Outline the principle of photoelectron spectroscopy.
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PART C
Answer any FOUR questions (4×12.5=50)
17. Explain with theory, the spectrum of linear diatomic molecules of rigid rotor type. Deduce the correction for non rigid type.
18. Explain the vibration spectrum of a diatomic molecule. Deduce the effect of anharmonicity.
The fundamental and first overtone transitions of CO are centered at 2143.3 cm-1 and 4260 cm-1. Calculate the equilibrium oscillation frequency, the anharmonicity constant and force constant of the molecule.
19. State the principle of ESR. With necessary diagram, explain how it is used to characterize samples.
20. Using family tree method, explain how spectral splitting is taking place in NMR spectroscopy due to coupling of other nuclei with suitable examples.
21. Outline the principles of Mossbauer spectroscopy. With a block diagram, explain the working of Mossbauer spectrometer.
22. Explain the principle, working and applications of electron energy loss spectroscopy (EELS).