2 Low temperature CIA data

Although models of the low temperature CIA spectra of hydrogen pairs exist already, they were given in the form of FORTRAN programs, separately for each spectral band. This has turned out to be inconvenient for many users, and has caused unnecessary troubles when the programs refused to work under various compilers or computer platforms. In order to ease the use of the data, the spectra at all bands (ranging from the roto-translational, to the roto-vibrational fundamental, first and second overtone transition) have been consolidated in one block of data. It is presented as a table of intensities (in cm^-1/amagat²) from 0 to approx. 16 500 cm^-1. The spacing is chosen to be 10 cm^-1 which should be sufficient for most applications and which is sufficient for high accuracy interpolation, if necessary. Hydrogen in thermal equilibrium was assumed everywhere.

The combined spectra are based on the following computer models, $\nu_0$ (cm^-1) being the vibrational transition wavenumber for the hydrogen molecule:
1. roto-translational band (RT) CIA (40-300 K) (Borysow et al. 1985), ($\nu_0=$ 0.0 cm^-1),
2. fundamental band $\nu_0=$ 4162 cm^-1 $\approx$ 2.4 $\mu$m, (20-300 K) (Borysow 1991),
3. first overtone band, $\nu_0=$ 8089 cm^-1 $\approx$ 1.2 $\mu$m, (20-500 K) (Zheng & Borysow 1995),
4. second overtone band, $\nu_0=$ 11786 cm^-1 $\approx$ 0.8 $\mu$m, (50-500 K) (Borysow et al. 2000).

www.astro.ku.dk/~aborysow/programs. A few of the models provide reliable predictions only up to 300 K, and the use of the models above the designed limits is strongly discouraged. The data combined in the table are all for temperatures up to 350 K. The data for temperatures from 150 to 350 K are shown on Fig. 1. The data for 60 and 100 K can be found in the table on the Internet.