Photochemistry Standards

Science in the photoswitching and photochemistry fields would be better if photochemical/photoswitching setups were described conveniently and sufficiently.

Several "minimal guidelines for describing photochemistry" are published; a good overview of the basics by Lee Edwards (GSK) is open access in Nat Commun at dx.doi.org/10.1038/s41467-019-13988-4 (2020). Excerpt:

"One way to think of a photon is as a reagent. Therefore, just like any reagent, we should know how many photon equivalents are added to our reaction mixtures. Information on the light source, photon stoichiometry, internal reaction temperature, light intensity, distance between the light source and reaction mixture, and path length are all key... With these parameters, it is our belief that the transfer of reactions between set-ups will be simplified for all chemists… Any photochemical publication should characterize [factors including]
- the spectral output of the light source used… The inability to compare light source outputs causes the reproducibility challenges with which we are currently faced.
- the photon output of the light source used (i.e., photon equivalents)… The photochemical effect is directly proportional to the total energy dose, irrespective of the time to deliver the dose (intensity of light × time of exposure = constant). This often-forgotten law underlines the effect that light intensity has on reaction kinetics.
- the actual illuminated surface area [and path length, non-illuminated volume]..."

A more recent paper focusing on photoreactivity:
Scaiano 2023 Chem Rev, https://doi.org/10.1039/D3CS00453H;
"A beginners guide to understanding the mechanisms of photochemical reactions: things you should know if light is one of your reagents".