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The NASA Ames PAH IR Spectroscopic Database

The family of emission features formerly known as the Unidentified Infrared (UIR) bands which were discovered some thirty five years ago are now generally attributed to polycyclic aromatic hydrocarbons. The features that comprise this apparently universal spectrum contain a wealth of information about the conditions in the emitting regions and the nature of the PAH carriers. However, exploitation of these features as astrophysical and astrochemical probes has been slow in coming because the IR properties of PAHs under interstellar conditions were largely unknown for at least twenty years after the bands were discovered and the experimental and computational tools needed to provide these data were not fully developed.

We have developed the tools needed to match observed interstellar infrared emission spectra to the spectra of a composition of polycyclic hydrocarbon (PAH) molecules. The tools will convert the NASA Ames PAH IR Spectroscopic Data into synthetic emission spectra depending on the local conditions, such as the excitation temperature and average UV photon energy.

The content of the database, the website and its accompanying tools have been described in two inaugural papers. The first paper deals with the data obtained through density functional theory, the second with those data obtained through laboratory experiment. Both papers can be downloaded below, together with the website documentation. Help on citing papers can be found here.

A significantly updated version of the NASA Ames PAH IR Spectroscopic Database, the first major revision since its release in 2010, was released as version 2.00. Version 2.00 has added experimental and computational content, updated (on)offline tools and a totally rewritten website. A paper describing the updated NASA Ames PAH IR Spectroscopic Database can be downloaded below. The library of theoretically calculated PAH spectra was updated to version 3.00 in 2018, which saw a dramatic increase in content and introduced the use of multiple scaling factors. Help on citing papers can be found here.

Website documentationVersion 3.00 paper - Version 2.00 paperTheoretical paper - Laboratory paper

Since FY2019 the NASA Ames PAH IR Spectroscopic Database is being supported through a directed Work Package at NASA Ames titled: "Laboratory Astrophysics – The NASA Ames PAH IR Spectroscopic Database".

Since FY2023 the NASA Ames PAH IR Spectroscopic Database is being supported through the Laboratory Astrophysics Round 2 directed Work Package at NASA Ames.

Additional resources

Vibrational spectroscopy can be challenging. Therefore below a short list of usefull links:

Supplemental information on chemical and spectroscopic properties of PAHs can be found at the links below:

You are kindly asked to consider the following references for citation when using the database:

700 species present in version 2.00 of the theoretical database (Oct 29, 2013)