Branch II Physics
Duration: 3 hours
Maximum mark: 75
(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.
(Answer all questions. Each
question carries 15 marks.)
IIA.
Derive an expression for Landes 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.
(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