Electrostatic peak shifting

A major advantage of fluorescence as a sensing property stems from the sensitivity to the precise local environment of the intensity, i.e., quantum yield (excited state lifetime (xf), and peak wavelength (Xmax). In particular, it is the local electric field strength and direction that determine whether the fluorescence will be red or blue shifted and whether an electron acceptor will or will not quench the fluorescence. An equivalent statement, but more practical, is that these quantities depend primarily on the change in average electrostatic potential (volts) experienced by the electrons during an electronic transition (See Appendix for a brief tutorial on electric fields and potentials as pertains to electrochromism). The reason this is more practical is that even at the molecular scale, the instantaneous electric... 

OMPA H2O in acetone was also measured, and the peaks are again shifted to slightly shorter wavelengths. If these shifts are an accurate measure of covalent bonding, the bonding in complexes of OMPA with rare earth ions must be essentially electrostatic. Earlier work with... 

In hexamethylphosphotriamide systems the interaction of the dissolved salt cations with solvated electrons in general causes the solvated electron absorption peak to slightly shift towards the shortwave region. This can be put down to electrostatic interaction of cations and solvated electrons, which should cause a cationic atmosphere around the solvated electrons, and, at quite high concentrations of the electrolyte should form noncontacting (i. e. solvent-separated) ion pairs and triple ions Thus, it may be considered that a longwave absorption band in hexamethylphosphotriamide results both from unbound solvated electrons and the solvated electrons that weakly interact electrostatically with cations. And the data on ESR spectra are indicative of the absence of contact interaction between... 

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