Photophysics Stokes-shift

The discriminatory emission properties between two-coordinate d ° gold(I) complexes and their respective three-coordinate counterparts have been demonstrated in the literature [6, 10-13]. As discussed in the later sections, Che and coworkers have rationalized that the extraordinarily large Stokes shift of the visible emission of [Au2(diphosphine)2] from the [5da 6pa] transition is due to the exciplex formation ofthe excited state with solvent or counterions [6]. Fackler [14—16] reported the photophysical properties of monomeric [AUL3] complexes, which show visible luminescence with large Stokes shifts (typically lOOOOcm ), suggesting significant excited-state distortion. Gray et al. [10] examined the spectroscopic properties of... 

Chapter 3 is devoted to the characteristics of fluorescence emission. Special attention is paid to the different ways of de-excitation of an excited molecule, with emphasis on the time-scales relevant to the photophysical processes - but without considering, at this stage, the possible interactions with other molecules in the excited state. Then, the characteristics of fluorescence (fluorescence quantum yield, lifetime, emission and excitation spectra, Stokes shift) are defined. 

Dithienoborole 11 displays a bright green fluorescence at 534 nm in THF, an absorption band at 369 nm attributed to the 7t-7t transition of the 7t-electron unit, and an intense band at 438 nm. The positions of the absorption and fluorescence bands in 11 are independent of solvents such as dimethylformamide (DMF) and hexane. The Stokes shift (100 nm) supports an earlier correlation given between boron vacant p orbital and photophysical properties <2004CC68>. 

The technique of transient grating spectroscopy has been reviewed, with particular emphasis on its application to monitoring non-radiative deactivation. A unified theory of time-resolved fluorescence anisotropy and Stokes shift spectroscopy has appeared. A separate review has considered the chemical and photophysical events occurring from upper excited states as accessed by multiphoton absorption techniques. ... 

A substantial literature exists describing experimental and theoretical studies of the photophysical processes of indoles. In part, this reflects the well-established use of the magnitude of the Stokes shift seen in fluorescence spectrum of the indole chromophore to probe the local environment of tryptophan residues in biological molecules [4]. However, it also reflects the complexity of indole photophysics and the fact that some aspects remain controversial. Only an overview is presented here, because a proper discussion of the photophysics of the indole ring would easily fill this chapter. Unfortunately, no recent, comprehensive review of the topic is available however, early publications have been summarized [4,5], and recent papers in this area provide leading references and excellent brief reviews of subsequent work [6]. 

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