The FAST-JX photolysis mechanism (Wild et al., 2000) efficiently represents tropospheric photolysis, and is commonly implemented in CTMs like GEOS-Chem (e.g. https://wiki.seas.harvard.edu/geos-chem/index.php/FAST-JX_v7.0_photolysis_mechanism).

The code required to format new quantum yield and cross-section data into FJX is complex and somewhat opaque. I've tried to re-render it into more comprehensible R code that mimics the behavior of the original fortran while being comprehensible. This code requires an input file formatted in the same way as Prather's original.

Note that Prather's code contains a feature that is note immediately obvious. For an example of this, please look at the file XMeVK_JPL11X.dat. In that file, both line 6 and line 13 contain three temperature values in Kelvin. IF THESE TEMPERATURE VALUES ARE NOT IDENTICAL, the code will interpolate between the temperature values, while keeping values within the Temperature range set in line 13. I do not understand why you would want this behavior in the code, but I have included it in this to be consistent. However, I strongly recommend against using it.

Wild, O., X. Zhu, and M. J. Prather, Fast-J: Accurate simulation of in- and below-cloud photolysis in tropospheric chemical models, J. Atmos. Chem., 37, 245–282, 2000.