Fluorescence quenching isooctane

AOT-isooctane-H20 reversed micelles 50-A-diameter CdS particles generated in situ in reversed micelles from CdCl2 or Cd(N03)2 by H2S Reversed-micelle-entrapped CdS was fluorescence quenched by methylviologen band-gap excitation in the presence of Rh as catalyst and PhSH as sacrificial electron donor resulted in water photoreduction 611... 

This phenomenon appears to be quite general since triethylamine quenches acenaphthene singlets in acetonitrile at the rate of 2 x 109 M-1 sec-1 as determined by intensity and lifetime measurements. Quenching of triphenylene fluorescence also occurs at this rate in acetonitrile but is two orders of magnitude slower in isooctane. P. S. Engel, Unpublished results. 

Figure 2. (Top) Stern-Volmer plots for the quenching of the fluorescence of colloi fcl CdS in AOT-entrapped water pools in isooctane by RMV + (0), MV2+ 4Q), and PhSH (0) (Bottom) Absorption and emission spectra of colloidal CdS in AOT entrapped water pools in isooctane. The shoulder observed at 400 nm is due to a spectrometer artifact.

X 10 for cyclohexene, 2.3 x 10 for 1,3-cyclooctadiene, 2.0 x 10 for cyclohexane all in M- s" from Ref. [288]. Rate constant for 2,5-dimethyl-2,4-hexadiene refers to cumyloxyl in benzene. From Table 3.9. From Ref. [215] in acetonitrile. From Ref. [256] in acetonitrile for cyclohexene see also Refs. [258,259]. From Ref. [33] see also Ref. [72] in isooctane. Calculated from fluorescence lifetime in neat ethanol based on a lifetime in gas phase of 1030 ns. "From Ref. [230] in benzene/di-tert-butoxyperoxide (1/2). "From Ref. [289] in benzene. °From Ref. [288] in chlorobenzene Ref. [290] in benzene/di-ferf-butoxyperoxide (1/2). Values for cumyloxyl radicals can be found in Refs. [288,291,292]. PFrom Ref. [74] in benzene. From Ref. [291] in benzene see also Refs. [74,293]. From Ref. [232] in benzene at 37°C. Value for diethylsulfide. From Ref. [294] in benzene." From Ref. [70] in neat acetone. For quenching of triplet acetone by n-propylamine and triethylamine in acetonitrile see also Refs. [172,271]. In the case of alkoxyl radicals the values for cumyloxyl radicals are reported. From Refs. [29,231] reaction with fert-butoxyl radicals in benzene/di-tert-butoxyperoxide (1/2). Values not reported in table n-propylamine 1.6 x 10 M s, diethylamine ... 

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