two-photon process

https://doi.org/10.1351/goldbook.T06542
A photophysical or photochemical event triggered by a two-photon excitation.
Source:
PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2282 (https://doi.org/10.1351/pac199668122223)