Model question paper

 

III Semester MSc Degree Examination, November 2002

 

Branch II Physics

 

PH232 Atomic & Molecular Physics

Duration: 3 hours                                                                                                                                         

Maximum mark: 75             

 

Part A

(Answer any five questions. Each question carries 3 marks.)

 

I a)   With the help of diagrams, explain the combination of  (i) s and px  orbitals,  (ii) two p orbitals

  b)   What are reducible and irreducible representations?

c)       Explain why diatomic molecules such as CO and  HF show rotational spectrum whereas N2, and  O2 do not.

d)       What are hot bands?

e)       What is Fermi resonance?

f)        Explain the following terms i) v¢ progression  ii) v¢¢ progression  iii) sequence.

g)       What is quadrupole relaxation?

h)       With examples explain the uses of Mossbauer spectroscopy in corrosion studies.

 

 

 

Part B

(Answer all questions. Each question carries 15 marks.)

 

IIA.   Derive an expression for Lande’s splitting factor and explain anomalous Zeeman effect of sodium D1 and D2  lines.

 

 (Or)

 

IIB.   (a) Discuss Heitler-London theory for Hydrogen molecule.

          (b) What is sv, sh, sd  symmetry operations.                                                          

 

 

IIIA. (a) Explain the rotational spectra of a rigid diatomic molecule.

         (b) Outline the effect of isotopic substitution on the rotational spectrum.

 

 (Or)

 

IIIB. (a) Explain the spectra of a diatomic vibrating rotator.

         (b) What approximation is used in explaining the spectrum?

 

 

IVA (a) Outline the principle of photoelectron spectroscopy.

        (b) Explain what is the chemical shift in relation to photoelectron spectroscopy.

 

 (Or)

 

IVB (a) Explain the principle of NMR and obtain the resonance condition.

        (b) Write the high resolution NMR Hamiltonian of a molecule and explain the terms.

 

 

 

Part C

 

(Answer any three questions. Each question carries 5 marks.)

V. (a)  The calcium line of wavelength l = 422.67 nm (p®s) exhibits normal Zeeman splitting, when    placed in a uniform magnetic field of 4 Wb/m2. Calculate the wavelength of three components of normal Zeeman pattern and the separation between them.

 

(b)   Write down the electronic structure of the following molecules in the M-O concept:

                                  (i)  XeF2         (ii) SeCl4          (iii) BCl3

 

(c)       The O-H stretching frequency of a compound is 3700 cm-1 . The sample is deuterated so that the

         hydrogen atoms are replaced by deuterium atoms. What will be the O-D stretching frequency?

 

(d)      Calculate the Stokes and antistokes rotational Raman displacements for quantum numbers

         J=1,2,3,4 and 5 for HCl molecule for which the rotational constant (B) is 10.34 cm-1 .

 

(e)       Calculate the magnetic field strength required to get a transition frequency 60 MHz for fluorine

        (gN  =5.255).

 (f)    The spectroscopic bond dissociation energy of Cl35O16 radical is 1.9 eV. Calculate the equilibrium bond dissociation energy of ClO, if the fundamental vibrational frequency is 780 cm-1.

 

 

 Go to: resources