I Semester M. Sc Degree Examination
PHYSICS: Atomic and Molecular Physics
Time: 3 Hours Max. Marks: 80
Answer all questions
1. a) Obtain an expression for the rotational energy of a diatomic molecule considering
rigid rotator model.
b) Briefly explain Born –Oppenheimer approximation (10+5)
2. a) With the help of energy level diagram, explain the rotational structure of electronic
b) Write a note on the formation of band head in rotational band spectra for
' ''
B B v v 
using Fortrat parabola. (10+5)
3. a) Describe the parameters of a molecular structure in detail.
b) Write the differences between electrovalent bond and covalent bond. (10+5)
4. a) Based on the Valence bond theory, explain the electrical conductivity of metals and
b) Briefly explain sp- hybridization along with its characteristics. (10+5)
5. a) Explain the processes of induced absorption, spontaneous emission and stimulated
emission in LASERS using Einstein’s coefficients.
b) Write a note on ‘coherence’ in Lasers. (10+5)

6. a) Explain the construction and working of He-Ne Laser. Mention its applications.
b) Write the applications of Holography techniques. (10+5)
7. a) Define Harmonic generation. How second harmonic generation can be observed
b) Explain the environmental application of Laser Raman Spectroscopy. (10+5)
8. a) What is mode locking of Lasers? Discuss with examples.
b) Explain Optical fiber communication briefly. (10+5)
9. Answer any FOUR of the following. (10+5)
a) Obtain an expression for rotational level with maximum intensity using Boltzmann
distribution law.
b) Write a note on non-rigid rotator
c) Explain lattice energy along with some examples.
d) What is close packing structure? Explain in brief.
e) What do you mean by pumping in Lasers? What are its types?
f) Discuss the construction of CO2 laser along with the neat diagram.
g) Explain why anti-Stokes’ lines are less intense than Stokes’ lines?
h) Write a note on the application of short pulse lasers?

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