Photophysics in the picosecond time range of the methylene blue-guanosine-5′-monophosphate complex

✍ Scribed by Mironel Enescu; Lahouari Krim; Lars Lindqvist; Wu Tieqiang

• Book ID: 103994335
• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 498 KB
• Volume: 22
• Category: Article
• ISSN: 1011-1344
• DOI: 10.1016/1011-1344(93)06971-5

✦ Synopsis

The complex of methylene blue with guanosine-5'-monophosphate was studied by transient absorption laser spectroscopy with 1 ps resolution.

The prompt transient spectrum was found to be similar to that of the free dye, while the excited-state lifetime is strongly reduced. Identical decays for S1-+S, absorption, ground-state bleaching and stimulated emission were obtained. The biexponential decay (lifetimes 8 and 160 ps, respectively) was found to be associated with time-independent shapes of these transient spectra. We conclude that the observed lifetime shortening is due to the enhancement of non-radiative transitions between S1 and S, by involvement of a low-lying charge transfer state, rather than to an electron transfer process with complete charge separation.