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Project Progress

The VPL database of molecular spectroscopic parameters contains a compilation of calculated and experimental linelists (including line positions, line intensities, lower state transition energies and broadening coefficients) combined with a collection of empirical absorption cross-sections for specific molecules of interest to planetary environmental and spectrum generating models. These data reside on the VPL’s supercomputer for use with the VPL atmospheric and spectral generation models. The publicly accessible website at http://vpl.ipac.caltech.edu/spectra/ provides spectral plots of the data, supplemental details about the molecule and the data sources. These include IR absorption cross-sections based on FTIR spectra recorded at the Pacific Northwest National Lab (PNNL), infrared line lists from the HITRAN (2004) database, and UV cross-sections from VPL scientists’ personal collections. The spectroscopic data can be requested by the astrobiology community via e-mail to VPL, or via the HITRAN website. Future spectroscopic data is expected to flow soon from the new Bruker HR125 spectrometer facility currently being assembled by L. R. Brown at the Jet Propulsion Laboratory.

The information tables and spectral images created for the VPL website were also linked to the HITRAN website (http://cfa-www.harvard.edu/HITRAN/) at the request of the HITRAN manager L. S. Rothman, and the information we collated for astrobiological use is now also being used by the wider molecular spectroscopy community.

This year we added an isotope page to this community resource (figure 1) (http://vpl.ipac.caltech.edu/spectra/isotopes/isotopes.htm). We also created a versatile, custom user interface that goes beyond the static spectra previously available on the website and allows users to plot specific wavelength or wavenumber ranges for a user-specified molecule from either the HITRAN or PNNL databases (http://savi.weber.edu/hi_plot/ ). These plots are often easier to read and measure, to enhance the user’s ability to identify a spectral feature (figure 2). This new interface also allows VPL members and collaborators to upload new line list and absorption coefficient data to the VPL central modeling database where they are then accessible to the other model components.

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