Nanosecond time-resolved resonance Raman spectra of the triplet states of DMABN, DMABN-d6, and DMABN-N15 have been obtained over the frequency range from 700 to 2300 cm-1. Isotopic shifts identify modes associated with the dimethylaniline subgroup. There is no significant difference between spectra recorded in polar and nonpolar solvents implying that the lowest triplet state (3T1) state has only one form. Our results characterize it as planar or near planar in structure, with a high negative charge localization on the cyano group and a substantial loosening of the ring skeleton with conjugation extending to the amino group. Nonradiative deactivation of the singlet intramolecular charge transfer state (1ICT) through intersystem crossing is discussed in relation to the transient absorption spectra.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry