Infrared spectroscopy of nitrous oxide, N2O

Nitrous oxide is a linear, three-atomic molecule with non-symmetric structure N-N-O. Inititally, the infrared spectrum of N2O will be recorded over a large spectral region using an FTIR (Fourier Transform InfraRed) instrument. This spectrum will show fundamental vibrational bands as well as a large number of overtone and combination bands all rotationally resolved. The combined analysis of the vibrational frequencies of these bands enables to determine the anharmonicity of the vibrational potential. An analysis of the rotational structure yields rotational constants for different vibrational states and makes the determination of rotation-vibration interaction possible.

After this introductory experiment, in a second step, the participants will perform infrared spectroscopy of one selected vibrational band using a quantum-cascade laser at high spectral resolution.

Summary of the spectroscopical concepts and more detailed description of the experiment.


  • P. F. Bernath, Spectra of Atoms and Molecules, Oxford University Press, 2005, (especially Chapter 6.2 and 7.2)
  • G. Herzberg, Molecular Spectra and Molecular Structure, II. Infrared and Raman Spectra of Polyatomic Molecules, Lancaster Press Inc., 1945, (especially Chapter II,5)
  • J. M. Hollas, Modern Spectroscopy, 4th edition, Wiley, 2004


Marius Hermanns,, Tel.: -3483
Oskar Asvany,, Tel.: -4529
Sven Thorwirth,, Tel.: -1936