Semester VI (Major, CBCS)

  Molecular Spectroscopy, Photochemistry, Surface Phenomenon 

1.   Molecular Spectroscopy(24 L) 

Interaction of electromagnetic radiation with molecules and various types of spectra; Born Oppenheimer approximation. Rotation spectroscopy: Selection rules, intensities of spectral lines, determination of bond lengths of diatomic and linear triatomic molecules, isotopic substitution. Vibrational spectroscopy: Classical equation of vibration, computation of force constant, amplitude of diatomic molecular vibrations, anharmonicity, Morse potential, dissociation energies, fundamental frequencies, overtones, hot bands, degrees of freedom for polyatomic molecules, modes of vibration, concept of group frequencies; Diatomic vibrating rotator, P, Q, R branches. Raman spectroscopy: Qualitative treatment of Rotational Raman effect; Vibrational Raman spectra, Stokes and anti-Stokes lines. Effect of nuclear spin, their intensity difference, rule of mutual exclusion. Nuclear Magnetic Resonance (NMR) spectroscopy: Principles of NMR spectroscopy, Larmor precession, chemical shift and low resolution spectra, different scales, spin-spin coupling and high resolution spectra, interpretation of PMR spectra of organic molecules. Electron Spin Resonance (ESR) spectroscopy: Its principle, Hyperfine structure, ESR of simple radicals. 

2. Photochemistry (18 L) 

Lambert-Beer’s law: Characteristics of electromagnetic radiation, Lambert- Beer’s law and its limitations, physical significance of absorption coefficients; Laws of photochemistry, Stark-Einstein law of photochemical equivalence quantum yield, actinometry, examples of low and high quantum yields. Photochemical Processes: Potential energy curves (diatomic molecules), Frank-Condon principle and vibrational structure of electronic spectra; Bond dissociation and principle of determination of dissociation energy (ground state); Decay of excited states by radiative and non-radiative paths; Pre-dissociation; Fluorescence and phosphorescence, Jablonski diagram. Rate of Photochemical processes: Photochemical equilibrium and the differential rate of photochemical reactions, Photostationary state; HI decomposition, H2-Br2 reaction, dimerisation of anthracene; photosensitized reactions, quenching; Role of photochemical reactions in 49 biochemical processes, photostationary states, chemiluminescence. 

3. Surface phenomenon(18 L) 

Surface tension and energy: Surface tension, surface energy, excess pressure, capillary rise and surface tension; Work of cohesion and adhesion, spreading of liquid over other surface; Vapour pressure over curved surface; Temperature dependence of surface tension. Adsorption: Physical and chemical adsorption; Freundlich and Langmuir adsorption isotherms; multilayer adsorption and BET isotherm (no derivation required); Gibbs adsorption isotherm and surface excess; Heterogenous catalysis (single reactant); Zero order and fractional order reactions. Colloids: Lyophobic and lyophilic sols, Origin of charge and stability of lyophobic colloids, coagulation and Schultz-Hardy rule, Zeta potential and Stern double layer (qualitative idea), Tyndall effect; Electrokinetic phenomena (qualitative idea only); Determination of Avogadro number by Perrin’s method; Stability of colloids and zeta potential; Micelle formation.  

Reference Books 

1. Castellan, G. W. Physical Chemistry, Narosa. 2. Levine, I. N. Physical Chemistry, Tata McGraw-Hill. 3. Atkins, P. W. & Paula, J. de Atkin’s, Physical Chemistry, Oxford University Press. 4. McQuarrie, D. A. & Simons, J. D. Physical Chemistry: A Molecular Approach, Viva Press. 5. Mortimer, R. G. Physical Chemistry, Elsevier. 6. Laidler, K. J.Chemical Kinetics, Pearson. 7. Banwell, C. N. Fundamentals of Molecular Spectroscopy, Tata-McGraw-Hill. 8. Barrow, G. M. Molecular Spectroscopy, McGraw- Hill. 9. Hollas, J.M. Modern Spectroscopy, Wiley India. 10. McHale, J. L. Molecular Spectroscopy, Pearson Education. 11. Wayne, C. E. & Wayne, R. P. Photochemistry, OUP. 12. Brown, J. M. Molecular Spectroscopy, OUP. 13. Levine, I. N. Quantum Chemistry, PHI. 14. Atkins, P. W. Molecular Quantum Mechanics, Oxford.