non-vertical energy transfer

Energy transfer process with a low Franck–Condon factor because the nuclear geometries of the minima on the ground- and excited-state potential energy surfaces of the donor or of the acceptor are strongly displaced.

Note:

A Franck–Condon transition is always vertical. Thus, it is not strictly correct to speak about non-vertical transition. However, the term implies that the projection of all the vibrational wave functions of the donor state onto all the vibrational functions of the acceptor will result in low Franck–Condon factors.

Source:

PAC, 2007, 79, 293 (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 374