title: Direct observation of delayed fluorescence from a remarkable back-isomerization in Cy5.
abstract: The direct observations of delayed fluorescence and phosphorescence from the cyanine dye Cy5 are reported. The delayed fluorescence is generated from the S(1) state of trans-Cy5 through a reserve intersystem crossing from the cis-triplet state T(1) to the trans-singlet state S(1) 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.
authors.affiliation: State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, P. R. China.
authors.forename: Zhengxi
authors.initials: Z
authors.lastname: Huang
authors.forename: Dongmei
authors.initials: D
authors.lastname: Ji
authors.forename: Andong
authors.initials: A
authors.lastname: Xia
authors.forename: Felix
authors.initials: F
authors.lastname: Koberling
authors.forename: Matthias
authors.initials: M
authors.lastname: Patting
authors.forename: Rainer
authors.initials: R
authors.lastname: Erdmann
mesh_terms: D002232:Carbocyanines / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D007536:Isomerism; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; C085321:cyanine dye 5