Femtosecond Spectroscopy and Dynamics of the Azulenylosquaric Dye, a Near-infrared Nonfluorogenic Quencher
Resource
Journal of the Chinese Chemical Society 53 (6): 1275-1283
Journal
Journal of the Chinese Chemical Society
Journal Volume
53
Journal Issue
6
Pages
1275-1283
Date Issued
2006
Date
2006
Author(s)
Yi‐Ming Cheng
I‐Che Wu
Chin‐Hung Lai
Shih‐Chieh Pu
Pi‐Tai Chou
Ching‐Yen Wei
Chao‐Ying Yu
Yi‐Hsin Lin
Ching Ting
Abstract
An azulenylosquaric dye (ASQ) has been synthesized to investigate its associated photophysical properties. ASQ is essentially nonluminescent (Φf < 3 × 10-6) in any solvent despite its very high absorption extinction coefficient (760 nm, ε ∼ 8.2 × 104 M-1cm-1 in methanol). Femtosecond fluorescence upconversion, anisotropy kinetics and transient absorption experiments, in combination with the theoretical time-dependent DFT approach, leads us to conclude that the 760 nm absorption is ascribed to the fully allowed S 0→Sn (n 2) transition. The observed < 130 fs decay component is attributed to the Sn→S1 internal conversion, while the S1→S0, with a slower radiative decay time (> 233 ns) undergoes a dominant radiationless deactivation process (710 70 fs) possibly governed by strong interaction between S1 and S0 potential energy surfaces.
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Type
journal article
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