non-radiative decay

https://doi.org/10.1351/goldbook.N04200
The disappearance of an excited species due to a radiationless transition.
Source:
PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2256 (https://doi.org/10.1351/pac199668122223)