Details

This Demonstration utilizes molecular constants of the molecule and the infrared spectrum is simulated at a temperature of 200 Kelvin.

molecular constants:

= 2990.946

= 52.8186

= 10.59341

= 0.30718

= 5.3194E-04

The intensity of the observed spectral lines reflects the dependence on the thermal population of the initial rotational energy levels and the dependence on the quantum number , not on the magnitude of the corresponding transition energy.

Note: the axis on the energy level diagram (top graphic) is arbitrary. The arrows indicating transitions in the top graphic are spread out for clarity and so that their positioning lies directly above the corresponding transition wavenumber in the spectrum below (bottom graphic).

References:

[1] P. Atkins and J. de Paula, Physical Chemistry, New York: Oxford University Press, 2006.

[2] G. Herzberg, Molecular Spectra and Molecular Structure I. Spectra of Diatomic Molecules, Princeton, New Jersey: D. Van Nostrand Company, Inc., 1950.

[3] K. P. Huber and G. Herzberg, Molecular Spectra and Molecular Structure IV. Constants of Diatomic Molecules, New York: Van Nostrand Reinhold Company, 1979.

[4] Diatomic Constants for HCl. webbook.nist.gov/cgi/cbook.cgi?ID=C7647010&Units=SI&Mask=1000# Diatomic (NIST Chemistry WebBook. webbook.nist.gov/chemistry).