The NASA Ames PAH IR Spectroscopic Database: A Demo of its Contents and Web Tools

The features formerly known as the Unidentified Infrared (UIR) Emission Bands are now generally attributed to polycyclic aromatic hydrocarbons (PAHs). Exploitation of these features as astrophysical and astrochemical probes requires the IR properties of PAHs under interstellar conditions. To fulfill this need, we experimentally measured and theoretically computed the 2-2000 µm spectra of many PAHs over the past 18 years at NASA's Ames Research Center. Today's collection comprises about 600 theoretically computed and 60 laboratory measured spectra of PAHs in different forms. The molecules in the collection range in size from C₁₀H₈ to C₁₃₀H₂₈. For most of these, spectra are available for PAHs in their neutral and singly charged (+/-) states. In some cases, IR spectra of multiply charged species were also computed. The database includes pure PAHs; PAHs containing nitrogen (PANHs), oxygen, and silicon; PAHs with side groups; PAHs with extra hydrogens; and PAHs complexed with iron and magnesium.

This collection of PAH spectra from 2 - 2000 µm has been assembled into a uniform database, which we will make publicly available on the web in early 2009. A WebGUI interface has been developed that can effectively interrogate the database using a variety of queries, such as formula, molecular name, charge, specific number of atoms, etc. Several molecules can be selected in such a process and one can obtain their 3-D structures, plot and co-add their spectra, adjust parameters such as the bandwidth, download their data and print graphs. The database can also be downloaded as a whole and IDL-routines are provided to interrogate it.

This talk will present an overview of the contents and the web-GUI tools of the NASA Ames PAH IR Spectroscopic Database. Hands-on demonstrations will be available at the SOFIA Booth.