Principles of Spectroscopy

Pre requisite: Interaction of electromagnetic radiation with matter. Characterization of electromagnetic radiation, quantisation of energy,

Regions of the spectrum, representation of spectra, basic elements of practical spectroscopy, signal-to-noise ratio – resolving power, line width – natural line broadening, Doppler broadening, Heisenberg uncertainity principle; intensity of spectral lines – transition probability, population of states, path length of sample; Born-Oppenheimer approximation; rotational, vibrational and electronic energy levels in molecules; transition moment, selection rules, Fourier Transform methods (IR and NMR)

Diatomic molecules as rigid rotors:  rotational energy levels, intensity of spectral lines, selection rules, effect of isotopic substitutions, calculation of bond length for linear, di- and tri-atomic molecules.
Diatomic molecules as non rigid rotors: rotational transition, centrifugal distortion constant, rotational spectra of linear and symmetric top poly-atomic molecules; Stark effect, nuclear and electron spin interaction and effect of external fields; applications.
 

IR spectroscopy: vibrating diatomic molecule- energy of diatomic molecules as simple harmonic oscillator, zero point energy, force constant, bond strengths, vibrational transitions and selection rules, anharmonicity, Morse potential energy diagram, vibrational transitions and selection rules; vibrational-rotational spectroscopy - breakdown of Born – Oppenheimer approximation rules, selection rules, P, Q, R branches; vibration of poly atomic molecules- symmetry and fundamental vibrations, normal mode of vibrations, skeletal vibrations, group frequencies, overtones, hot bands, fermi resonance bands; influence of rotation on the spectra of polyatomic molecules – parallel and perpendicular vibrations in linear and symmetric top molecules.
Raman spectroscopy: classical and quantum theories of Raman effect, Rayleigh and Raman scattering, stokes and antistokes radiation, molecular polarizability, selection rules; rotational Raman spectra – linear molecules, symmetric top and spherical top molecules; vibrational Raman spectra- symmetry and Raman active vibrations, rules of mutual exclusion; rotation- vibration Raman spectra of diatomic molecules, polarized and depolarized Raman spectra.

Self Study: Resonance Raman spectroscopy, coherent antistokes Raman spectroscopy CARS (brief idea)

Atomic spectroscopy: energy of atomic orbital, vector representation of momenta and vector coupling, spectra of hydrogen atom and alkali metal atoms.
Molecular spectroscopy: energy levels, molecular orbitals, vibronic transitions, vibrational progression; geometry of excited states, Franck-Condon principle, emission spectra, radiation and non-radiation decay, internal conversion.
 Photoelectron spectroscopy: basic principle, ionization process, Koopmen’s theorem,
 photoelectron spectra of simple molecules, ESCA and its applications, Auger electron spectroscopy (basic idea).

Self Study: Spectra of transition metal complexes, charge transfer spectra.
 

Electron spin resonance spectroscopy: basic principles, zero field splitting and Kramer’s      degeneracy, factors affecting ‘g’ value, hyperfine coupling, isotropic and anisotropic hyperfine coupling constant, spin Hamiltonian, spin densities and McConnell relationship, measurement techniques, spin polarization for atoms and transition metal ions, application to transition metal complexes (having one unpaired electron) including biological systems and to inorganic free radicals such as PH4, F2- and [BH3]-.
Mossbauer spectroscopy: basic principles, spectral parameters and spectrum display, application of technique to studies of bonding and structure determination of Fe+2, Fe+3, Sn+2 and Sn+4 compounds.