quencher

https://doi.org/10.1351/goldbook.Q05006
A molecular entity that deactivates (quenches) an
excited state
of another molecular entity, either by energy transfer,
electron transfer
, or by a chemical mechanism.
See:
quenching
,
Stern–Volmer kinetic relationships
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2268 [Terms] [Paper]