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Manuscript Title: Analysis of the intensity distribution in the rotational structure of the electronic spectra of diatomic molecules by computer simulation.
Authors: R.Ch. Baas, C.I.M. Beenakker
Program title: ROSCOS
Catalogue identifier: ACRW_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 8(1974)236
Programming language: Algol.
Computer: E1-X8.
Operating system: MILLI.
RAM: 39K words
Word size: 27
Peripherals: graph plotter.
Keywords: Molecular physics, Diatomic, Wavelength, Molecular physics, Diatomic, Wavelength, Line-strengths, Intensity.
Classification: 16.2.

Nature of problem:
This program is concerned with the analysis of the intensity distribution in the rotational structure of the CH spectrum, produced by dissociative excitation of simple aliphatic hydrocarbons (CH4, C2H2, C2H4, C2H6) by electron impact.

Solution method:
If the resolving power of the monochromator does not allow one to separate all lines contributing to the spectrum, the intensity distribution in the rotational structure can be established by simulation of the experimental spectrum on the computer by a convolution technique. For this purpose, the wavelengths, line-strengths and intensities of the rotational transitions are calculated. Relevant formulae are given by Kovacs. The wavelengths, which have been determined experimentally by Gero, are read in. The intensity is calculated by applying a Boltzmann distribution over the rotational levels.

Restrictions:
The program is restricted to the calculation of a A**2 delta-**2II transition. It can also be applied to singlet-singlet and other doublet-doublet trasnitions, when relevant parts of the formulas are changed.

Running time:
The running time depends on the number of lines to be convoluted. The test run required 225 s for 1714 lines, including compilation, loading and syntax control.