Publication Date:
2011-08-24
Description:
This program predicts the spectra resulting from electronic transitions of diatomic molecules and atoms in local thermodynamic equilibrium. The program produces a spectrum by accounting for the contribution of each rotational and atomic line considered. The integrated intensity of each line is distributed in the spectrum by an approximate Voigt profile. The program can produce spectra for optically thin gases or for cases where simultaneous emission and absorption occurs. In addition, the program can compute the spectrum resulting from the absorption of incident radiation by a column of cold gas or the high-temperature, self-absorbed emission spectrum from a nonisothermal gas. The computed spectrum can be output directly or combined with a slit function and sensitivity calibration to predict the output of a grating spectrograph or a fixed wavelength radiometer. Specifically, the program has the capability to include the following features in any computations: (1) Parallel transitions, in which spin splitting and lambda doubling are ignored (ignoring spin splitting and/or lambda doubling means that the total multiple strength is assumed to reside in a single "effective" line), (2) Perpendicular transitions, in which spin splitting and lambda doubling are ignored, (3) Sigma Pi transitions, in which lambda doubling is ignored, (4) Atomic lines, (5) Option to terminate rotational line calculations when the molecule dissociates due to rotation, (6) Option to include the alternation of line intensities for homonuclear molecules, (7) Use of an approximate Voigt profile for the line shape, and (8) Radiative energy transport in a nonisothermal gas. The output options available in the program are: (1) Tabulation of the spontaneous emission spectrum (i.e., optically thin spectrum) for a 1.0 cm path length, (2) Tabulation of the "true" spectrum, which incorporates spontaneous emission, induced emission, absorption, and externally incident radiation through the equation of radiative transfer, (3) Tabulation of the curve of growth for an arbitrary number of wavelength intervals, (4) Tabulation of the integrated intensity over an arbitrary number of wavelength intervals, and (5) Tabulation of the output signal produced by a radiometer or spectrometer by specifying an instrument calibration. The instrument slit function can be approximated by up to 99 straight line segments or by a Gaussian curve. The computation can be made at a fixed wavelength to simulate a radiometer or by scanning across any specified wavelength interval to simulate a grating instrument. In the latter case, the sensitivity can be varied as a function of wavelength to accurately simulate a grating-instrument calibration. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 7000 Series computer. This program was developed in 1968.
Keywords:
CHEMISTRY AND MATERIALS (GENERAL)
Type:
ARC-10221
Format:
text
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