ExoPhoto: A Database of Temperature-Dependent Photodissociation Cross Sections

TL;DR

ExoPhoto is a comprehensive database that provides temperature-dependent photodissociation cross sections for 20 molecules, integrating theoretical models and experimental data to support astrophysical and industrial applications.

Contribution

It introduces a new database, ExoPhoto, combining multiple data sources for high-accuracy, temperature-dependent photodissociation cross sections in a standardized format.

Findings

Includes data for 20 molecules relevant to astrophysics.

Combines theoretical and experimental datasets for accuracy.

Supports future expansion for non-LTE molecules.

Abstract

We present the ExoPhoto database (https://exomol.com/exophoto/), an extension of the ExoMol database, specifically developed to address the growing need for high-accuracy, temperature-dependent photodissociation cross section data towards short-UV wavelengths. ExoPhoto combines theoretical models from three major computational databases (ExoMol, UGAMOP and PhoMol) and experimental datasets from two experimental groups, providing extensive wavelength and temperature coverage. ExoPhoto currently includes photodissociation data for 20 molecules: AlH, HCl, HF, MgH, OH, NaO, MgO, O2, AlCl, AlF, CS, HeH+, CO, CO2, H2O, SO2, C2H2, C2H4, H2CO, and NH3, derived from theoretical models and supported by experimental data from 5 databases. ExoPhoto also includes detailed data on branching ratios and quantum yields for selected datasets. The data structure of ExoPhoto follows the ExoMol framework, with a consistent naming convention and hierarchical JSON-based organization. Photodissociation cross sections are stored in a set of .photo files which provide data as a function of wavelength with one file for each target molecule temperature. Future developments aim to include more photodissociation cross section data and to provide data for molecules in non-local thermodynamic equilibrium (non-LTE). These will expand the utility of ExoPhoto for advanced astrophysical, planetary modeling and industrial applications.