Direct Observation of Delayed Fluorescence from a Remarkable Back-Isomerization in Cy5
journal contributionposted on 08.06.2005, 00:00 by Zhengxi Huang, Dongmei Ji, Andong Xia, Felix Koberling, Matthias Patting, Rainer Erdmann
The direct observations of delayed fluorescence and phosphorescence from the cyanine dye Cy5 are reported. The delayed fluorescence is generated from the S1 state of trans-Cy5 through a reserve intersystem crossing from the cis-triplet state T1 to the trans-singlet state S1 via thermal activation. The lowest cis-triplet state is evidenced to be involved in the formation of the isomer. The back-isomerization from cis-triplet state to trans-singlet state crossing, a remarkably back-isomerization pathway that has not been reported before, plays a significant role in this unusual delayed fluorescence.