Photochemical process in the crystal lattice of a photoactive compound or of a chromophore in the crystal lattice of host molecules. Often asymmetric photochemistry takes place.
Source:
PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 319 (https://doi.org/10.1351/pac200779030293)