Optical properties, spectroscopy solvatochromism

Molecular rotors are useful as reporters of their microenvironment, because their fluorescence emission allows to probe TICT formation and solvent interaction. Measurements are possible through steady-state spectroscopy and time-resolved spectroscopy. Three primary effects were identified in Sect. 2, namely, the solvent-dependent reorientation rate, the solvent-dependent quantum yield (which directly links to the reorientation rate), and the solvatochromic shift. Most commonly, molecular rotors exhibit a change in quantum yield as a consequence of nonradia-tive relaxation. Therefore, the fluorophore s quantum yield needs to be determined as accurately as possible. In steady-state spectroscopy, emission intensity can be calibrated with quantum yield standards. Alternatively, relative changes in emission intensity can be used, because the ratio of two intensities is identical to the ratio of the corresponding quantum yields if the fluid optical properties remain constant. For molecular rotors with nonradiative relaxation, the calibrated measurement of the quantum yield allows to approximately compute the rotational relaxation rate kor from the measured quantum yield [Pg.284]

Several photophysical and ultrafast spectroscopic studies were undertaken in these RTILs [20-69]. Aki et al. [20] determined the polarity of the imidazolium-andpyiidinium-based RTILs using UV-Vis absorption and fluorescence spectroscopy. Muldoon et al. [21] determined the polarity of the RTILs using solvato-chromic probes. Carmichael et al. [22] determined the polarity of several neat l-aIkyl-3-methylimidazolium-based RTILs using the solvatochromic dye Nile red. Using Prodan, pyrene, 1-pyrenecarboxaldehyde, Reichardt s betain dye, and Rhodamine 6G as the solvatochromic probes various bulk properties and polarity of various RTILs-cosolvents mixtures were determined [23-26]. Recently, one excellent review article was published by Reichardt to determine the polarity of RTILs by means of solvatochromic betaine dyes [27]. Femtosecond optical Kerr effect... 

Volume 3 contains 16 chapters dealing with photoelectron spectroscopy, spectroelectrochemistry, crystallography scanning force microscopy, optically detected magnetic resonance studies of conductive polymers and fullerenes, magnetic properties, microwave properties, electrochemistry, electrocatalytic properties, metallic properties of conductive polymers due to dispersion, thin film properties of oligothiophenes, electrochromism, thermochromism, solvatochromism, degradation and stability of conductive polymers. 

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