M.Sc. DEGREE EXAMINATION, NOVEMBER 2017
Third Semester
Physics
ATOMIC AND MOLECULAR PHYSICS
(CBCS 2014 onwards)
Time 3 Hours Maximum 75 Marks
Part A (10 x 2 20)
Answer all questions.
1. What are known as equivalent electrons?
2. Give the meaning of two electron systems.
3. What is called Paschen Back effect?
4. What is Born-Oppenheimer approximation?
5. Why are pure rotational spectra studied only in the
gaseous states of atoms and molecules?
6. Define Morse function.
7. Explain Raman effect with the help of an energy level
diagram.
8. State Franck-Condon principle.
9. The Hyperfine structure of ESR lines is formed due to
which type of interaction.
10. What is Larmour frequency?
Sub. Code
4MPH3C2
AFF-4870
2
wk12
Part B x 5 25)
Answer all the questions choosing either or
11. Explain the various spectral series of Hydrogen
spectrum.
Or
Explain in detail about the transitions responsible
for D and F series of alkali spectrum.
12. Explain the phenomenon of anomalous Zeeman
effect. Describe the expression of l and s separately
about the external magnetic field.
Or
What are bonding and antibonding MOs? Explain.
13. Give the theory of vibration spectra treating the
harmonic vibrations of diatomic molecule.
Or
Compare the rotational spectra of linear, symmetric
top and asymmetric top molecules.
14. Discuss the vibrational Raman spectra by
explaining the Raman activity of vibrations.
Or
The spectroscopic bond dissociation energy of
35Cl16O molecule is 1.9 eV. Calculate the
equilibrium bond dissociation energy of ClO, if the
fundamental vibrational frequency is 780 .
15. Explain chemical shift with its significance.
Or
Explain the working principle of ESR spectrometer
with a neat block diagram.
AFF-4870
3
wk12
Part C x 10 30)
Answer any three questions.
16. Discuss the spin-orbit interaction and fine structure in
alkali spectra.
17. Describe the necessity of a resonator. What are
different types of resonators?
Explain coherence time and coherence length.
18. Discuss IR rotation-vibration spectra of diatomic
molecular. Derive an expression for P and R branches.
19. Explain band origin and band head in relation to the
rotational fine structure of electronic vibration spectra.
20. Explain the hyperfine structure of
H2 atom
one electron system coupled to a nucleus of spin l 1
unpaired electron coupling with two equivalent nuclei
of spin
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