red shift

https://doi.org/10.1351/goldbook.R05211
Informal term for bathochromic shift (effect).
Source:
PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2270 (https://doi.org/10.1351/pac199668122223)