Download M.Sc. Chemistry "Group Theory, Spectroscopy and Diffraction Methods" Question Paper-3 of 2nd Semester M.Sc. Chemistry.

M.Sc. Chemistry 2nd Semester
Group Theory, Spectroscopy and Diffraction
Methods

 Paper: IV

Time Allowed: Three Hours]   [Maximum Marks: 80

Note: Attempt five questions in all. Question No. IX is compulsory. Attempt one question from each of the four Units. All questions carry equal marks, students can use log table and n programmable calculator.

(Compulsory Question)

I. Answer each part of this question in 4-5 lines only.

(a) Give examples of molecules with point group CXV and D Clearly showing various elements of symmetry in suitable diagrams.

(b) State Franck Condon Principle. Draw diagram to illustrate the various transitions.

(C) A compound C10 H14 shows two singlet peaks in its p spectrum at.

(i) 8=8 ppm

(ii) 8 = 1 ppm with relative intensity of peaks 5:9 respectively. Predict the structure of the compound.

(d) Calculate the rotational content B'ofD-Cl molecule if rotational constant Bof HCl molecule is 10.6 cm1, assuming equal bond lengths of both molecules

.

(e) Why is NMR spectrum observed in radio frequency region while ESR spectrum is observed in microwave region?

(f) What is Coherent Anti Stoke Raman Spectroscopy? Write any four of its uses.

(g) What do you mean by hot bands in IR Spectroscopy? Explain.

(h) What are Miller Indices? Write ratio of interplanar distance in different types of crystal planes present in FCC, BCC, and SC crystals? How can these ratios be helpful to arrive at the structures of NaCl using X-ray diffraction?

UNIT-I

II. (a) Write complete sets of all elements of symmetry in BF, and staggered ethane molecules. Illustrate using simple diagrams. Assign point group to each molecule.

(b) Explain applications of group theory to find the symmetry of all normal modes of vibration in H2O molecule. Which modes are IR active? Explain.

III. (a) What is meant by Matrix Representation of a Point Group? Write such representations for various symmetry elements 

 

(b) Write properties of irreducible representations. Use them to construct a character table for C3v point group.

UNIT-II

IV. (a) Describe the classification of molecules according to their shapes. What type of molecules can show pure rotation spectra?

(b) Briefly explain the effect of nuclear and electron spin interaction on rotational Raman Spectra of Co2 molecule.

V. (a) What is an Anharmonic Oscillator? Write expression for vibrational energy levels of such an oscillator. Draw Morse potential energy diagram.

(b) What is meant by a normal mode of vibration, coupling of resonance, overtones, Fermi resonance and group frequencies in IR spectroscopy?

UNIT-III

VI. (a) Explain radiative and non-radiative decay during de-excitation of excited molecules. Show in the form of a suitable diagram.

(b) Discuss charge transfer spectra of transition metal complexes.