Molecular Spectroscopy | Department of Chemistry

Molecular Spectroscopy

In this course, Rotational, Vibrational, UV-Visible, Fluorescence, Mass and NMR spectroscopy methods will be taught. Chemists often adopt these techniques to identify the electronic and molecular structures of chemical and biochemical systems. Students will achieve a knowledge about the behaviour of molecular systems in presence of an external electromagnetic field in different frequency ranges. The principle along with comprehensive theories for each of the spectroscopy method will be discussed in the classes.

Course Aims

The main aim of this course is to provide students a concept about how these commonly used molecular spectroscopy techniques work, a theoretical knowledge of each of these methods and their usage in molecular and electronic structure determination.

Learning Outcomes

On successful completion of the course, students will be able to

(i) explain the behaviour of molecular systems in external electromagnetic field.

(ii) understand the principles and theories of rotational, vibrational, UU-Vis, Fluorescence, Mass and NMR spectroscopy methods.

(iii) interpret the molecular spectra and find molecular properties from molecular spectra.

Curriculum Content

Introduction: Meaning of spectroscopy and use of different spectroscopic tools to understand diverse applications.

Origin of a spectra: Revision of electromagnetic spectrum and Energy associated with them, factors affecting line broadening and intensity of lines, selection rules.

Rotational spectroscopy: Rotational spectroscopy of diatomic molecules, Effect of isotopic substitution, Non-rigid rotator, Application of rotational spectroscopy.

Vibrational spectroscopy: Vibrational spectroscopy, vibration-rotation spectrum, breakdown of Born-Oppenheimer Approximation, vibration of polyatomic molecules, applications.

UV-vis spectroscopy: Theory of UV-Vis/electronic spectroscopy: Lambert-Beer’s Law, Woodward-Fieser Rules, Chemical analysis by electronic spectroscopy.

Fluorescence spectroscopy: Introduction to fluorescence spectroscopy: Jablonski diagram, Frank-Condon principle, Stokes shift, solvent relaxation, solvatochromism, excimer and exciplex formation, quantum yield & life time. Spin-orbit coupling.

Mass spectroscopy: Introduction to mass spectroscopy: isotope effect, fragmentation patterns, applications.

Nuclear Magnetic Resonance (NMR): Theory of NMR, isotopes, Spinning nucleus, effect of an external magnetic field, precessional motion and precessional frequency, and the field strength, temperature effect, Boltzman distribution, origin of chemical shift and its implication in magnetic field strength, anisotropic effect, proton NMR spectrum, carbon NMR, concept of multi-dimensional NMR, influence of restricted rotation, fluxiaonal molecules, conformational dynamics, solvents used in NMR, solvent shift and concentration and temperature effect and hydrogen bonding, spin-spin splitting and coupling constants, chemical and magnetic equivalence in NMR, factors influencing the coupling constant, geminal coupling, vicinal coupling, heteronuclear coupling, deuterium exchange.



  1. Basics of Spectroscopy.
  2. Origin of Spectra and factors affecting the spectral line and intensity.
  3. Rotational Spectroscopy.
  4. IR Spectroscopy tutorial (characteristic absorption of common classes of organic compounds)
  5. IR Spectroscopy tutorial (application of IR spectroscopy to isomerism, identification of functional groups)
  6. IR Spectroscopy tutorial (effects of water and hydrogen bonding)
  7. UV Spectroscopy tutorial (calculation of for conjugated organic compounds)
  8. UV Spectroscopy tutorial ( for α, β unsaturated organic compounds and solvent effects)
  9. Role of fragmentation and rearrangement reaction during mass spectroscopic analysis.
  10. Application of shielding and deshielding effects.
  11. Chemical shift and coupling constants of alkane.
  12. Chemical shift and coupling constants of alkenes and alkynes.
  13. Assignment of 1H and 13C NMR signals of aromatic compounds.
  14. How to determine enantiomeric excess by NMR spectroscopy.
  15. Interpretation of 2D NMR and it’s application for the characterization of organic molecules.

Recommended Books:

  • Fundamentals of Molecular Spectroscopy (McGraw-Hill 1995) by C. N. Banwell  and E.M. McCash
  • Atkins' Physical Chemistry (Oxford University Press 2010) by Peter Atkins and Julio De Paula
  • Spectrometric Identification of Organic Compounds (John Wiley & Sons 2005) by R. M. Silverstein and F. X. Webster.
  • Basic One and Two – Dimensional NMR Spectroscopy (Wiley – VCH 2011) by Horst Friebolin.
  • Organic Spectroscopy (Palgrave Macmillan 2008) by William Kemp.
  • Organic Spectroscopy (Springer 2005) by L D S Yadav

Prerequisites: Physical Methods in Chemistry (CHY213); Chemical Applications of Group Theory (CHY212).

Co-requisite: Chemical Binding (CHY311).

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