pdusu last year exam paper ;spectroscopy
M.Sc (previous) examination ,2019
chemistry
paper 4
spectroscopy
Unit-1
(a) Suppose for a rigid diatomic rotor, energy of 5th rotational energy level is 100 cm-1, calculate energy gap between first excited state & second excited state in term of cm-1
(b) Wnite a short note on Intensity of Spectral Lines.
2 (a) The microwave spectrum of gaseous HC consists of a series of equally spaced lines by 20.80 cm-1, Calculate the internuclear distance of the molecule
(Given Plank's constant= 6.626x10-34 Js,
Atomic mass of 1H = 1.673x10-27 Kg,
Atomic mass of 35CI = 58.06 x10-27 Kg)
(b) Classify the following species as Linear rotor(s), Symmetric Top (s), Asymmetric Top (s) and
Spherical Top (s).
3 (a) How would you distinguish in following pairs from IR Spectral data:
1 Methanoic acid and Ethanoic acid
(2) Ethyl nitrite and Nitroethane
(3)Bromoform and Tetrachloromethane
(4) Butanone and Ethanoyl Chloride
5 Dimethyl amine and Trimethyl amine
(b) Discuss metal ligand vibrations of metal carbonyls.
4 a) The vibrational levels Nal lie at the wave numbers 142.81, 427.31, 710.31, and 991.81 cm-1, Show that they fit the expression (v-frx Xev, and deduce the zero point energy, and dissociation energy of the molecule.
5 Write short notes on:
(1) Vibrational progressions and geometry of the excited states
(ii) Spectra of alkali metal atoms
( 3 ) ESCA
6.(a) Using FEMO theory, estimate the wave number of the lowest energy transition in the 1,3,5-hexatriene.
(b) Discuss Auger electron, spectroscopy.
(c) Write a short note on 'Frank-Condon Principle'.
(a) Predict 'number of signals' in 13C NMR spectra of following compounds:
[14)-annulene
[18)-annulene
p-xylene
1,3-dimethyl propadiene
1,4-diethyl-1-methyl cyclohexane
Ethanoic methanoic anhydride
(b) Discuss 'Powder Method' of crystal structure analysis.
(c) Discuss about the parameters of unit cell.
(a) Differenciate between electron diffraction and neutron diffracrtion.
(b) Discuss absolute configuration of molecules with suitable examples.