Principles of Spectroscopy

Paper Code: 
CHY 124
Contact Hours: 
Max. Marks: 

Course Objectives :

The course aims to impart knowledge of origin of basic principles of spectroscopy and its applications to rotational, vibrational, Raman, electronic and NMR spectroscopy.

Course Outcomes (Cos):                                                                                                         


Learning outcomes (at course level)

Learning and teaching strategies

Assessment Strategies

Paper Code

Paper Title

CHY 124

Principles of Spectroscopy     

The students will be able to-


CO18- describe working principle and selection rule of rotational, vibrational, Raman and electronic spectroscopy.

CO19- distinguish between various spectroscopic transitions and interpret data for molecular characterization.

CO20- apply quantum mechanical approach to NMR spectra (A2, AB and AX system).

Class lectures








Interactive quiz


Written test


Viva voce




Semester end examination


Unit I: 
Basic Elements of Spectroscopy

Uncertainty relation and natural line width, natural line broadening, doppler line broadening, pressure broadening, saturation broadening, removal of line broadening. signal-to-noise ratio, resolving power, intensity of spectral lines – transition probability, population of states, path length of sample. General components of an absorption experiment in various regions, dispersing elements, basic elements of practical spectroscopy, Born-Oppenheimer approximation:Rotational, vibrational and electronic energy levels in molecules, selection rules and their derivations, Fourier Transform methods (IR and NMR).

Unit II: 
Rotational Spectroscopy

Classification of molecules, linear triatomic molecule, intensities, energy levels and rotational spectra of symmetric top molecules, Stark effect, nuclear and electron spin interaction, effect of external field, applications.

Unit III: 
Vibrational Spectroscopy

Vibrational energies of diatomic molecule, anharmonicity, vibrational-rotational spectroscopy, P, Q, R branches, breakdown of Born-Oppenheimer approximation, selection rules, vibrations of poly atomic molecules, normal mode of vibrations, skeletal vibrations, group frequencies, overtones, hot bands, fermi resonance bands, factors affecting the band positions and intensities.

Raman spectroscopy: Classicaland quantum theories of Raman effect, molecular polarizability, selection rules, rotational Raman spectra-linear molecules, symmetric top and spherical top molecules, vibrational Raman spectra and rotational-vibrational Raman spectra of diatomic molecule, mutual exclusion principle, polarized and depolarized Raman spectra.

Resonance Raman Spectroscopy, Coherent AntistokesRaman Spectroscopy CARS (an elementary idea)

Unit IV: 
Electronic Spectroscopy

Atomic spectroscopy: Energy of atomic orbitals, vector representation of momenta and vector coupling (orbital and spin coupling), term symbols, spectra of hydrogen atom, alkali metal atoms, helium, alkaline earth metals and polyelectronic atoms.

Molecular spectroscopy: Energylevels, molecular orbitals- homonuclear and heteronuclear diatomic molecules, vibronic transitions, progression and sequences, derivation of Franck-Condon principle, dissociation and predissociation.Electronicspectra of polyatomic molecules: AH2 type molecules, formaldehyde andbenzene. Emission spectra, radiative and non-radiative decay, internal conversion.

Unit V: 
NMR Spectroscopy

Larmor precession, mechanism of spin-spin and spin-lattice relaxations and quantitative treatment of relaxations, quantum mechanical treatment of A2 system ,AB system and AX system, selection rules and relative intensities of lines.

  • Fundamentals of Molecular Spectroscopy; Fourth Edition; C. N.Banwell and E. M. Mc Cash; Tata McGraw Hill, New Delhi, 2017.
  • Modern Spectroscopy; Fourth Edition; J.M. Hollas; John Wiley and Sons, India, 2004.
  • Introduction to Molecular Spectroscopy; International Edition; G.M. Barrow; Tata McGraw- Hill, Singapore, 1999.
  • Physical Methods in Inorganic Chemistry; First Edition; R. S. Drago; Affiliated East-West Press Pvt. Ltd., New Delhi, 2012.
  • Analytical Chemistry – Theory and Practice; Third Edition; U. N Dash; S. Chand and Co., New Delhi, 2019.
  • Atomic and Molecular spectroscopy; First Edition; S.K.Dogra and H.S.Randhawa; Pearson Education, 2015.
  • Atom, Molecule and Spectrum;S.K.Dogra and H.S.Randhawa; New Age International (P) Limited, 2015.
  • NMR Spectroscopy: Basic Principles, Concepts and Applications in Chemistry; Third Edition; H.Gunther; Wiley-VCH, 2013.
  • Molecular Structure and Spectroscopy; Second Edition; G.Aruldhas; PHI Learning Private Limited, 2015.

Academic Year: