Aromatic ketone-naphthalene systems as absolute standards for the triplet-sensitized formation of singlet oxygen, O2(1.DELTA.g), in organic and aqueous media. A time-resolved luminescence study

Is Singlet Oxygen Formation Dominant in Triplet Quenching Processes? Measurement of the Quantum Yield of Singlet Oxygen Formation by the Time‐resolved Thermal Lens Method

“…The UsL,,/UT,T values are reproducible within 20.005. Although several investigators have found that the lo, lifetime becomes shorter with stronger excitation laser light (Ogilby and Foote, 1983;Gorman et al, 1987), the observed lifetime remains constant under our experimental conditions. a)A is described by the product of the quantum yield of the triplet formation (@,-J of the sensitizer and S, as Eq.…”

“…, with an increase of laser power) and the extent of the laser power dependence is similar to that of @A, we consider that the laser power dependence of OA comes from that of not from that of the quenching process by oxygen (SA). Gorman et al (1987) have also observed the excitation laser power dependence of @A in acetonitrile and cyclohexane by detecting the phosphorescence intensity from singlet oxygen, and interpreted it as the result of the laser power dependence of QlSc. They have suggested that the origin of the laser power dependence is the T-T absorption of the sensitizers.…”

Quenching of electronically excited states by molecular oxygen in fluid solution

“…Quenching of excited states by molecular oxygen has been studied for decades [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Poxter and Windsor [2] in 1958 reported a rate constant for quenching of triplet anthracene by oxygen in hexane solution of 4 x lo9 dm3 mol-1 s-1 while Ware [3] in 1962 showed that fluorescence quenching by oxygen of the singlet state of anthracene occurred with rate constants ranging from 3 to 3.9 x 1010 dm3 mol-1 s-1 in different solvents including p-xylene, benzene, methanol, n-heptane, toluene and acetone.…”

A Laser Flash Photolysis Study of 11-Cis-Locked Retinal Analogues

“…In the phosphorescence measurements we employed methodology similar to that used by Gorman and Rodgers. 32, 34 We employed a xenon chloride excimer laser (λ ) 308 nm) as the excitation source as opposed to 355 nm laser line employed by Gorman et al This precluded the possibility of employing the benzophenone/naphthalene standard. 34 Instead we chose direct photolysis of naphthalene which has a φ isc of 0.75 35 and an efficiency of singlet oxygen generation, S ∆ , in alkane solutions of 1.0.…”

“…32, 34 We employed a xenon chloride excimer laser (λ ) 308 nm) as the excitation source as opposed to 355 nm laser line employed by Gorman et al This precluded the possibility of employing the benzophenone/naphthalene standard. 34 Instead we chose direct photolysis of naphthalene which has a φ isc of 0.75 35 and an efficiency of singlet oxygen generation, S ∆ , in alkane solutions of 1.0. 32 To ensure that our apparatus was working correctly we measured singlet oxygen generation efficiencies, φ ∆ , for benzophenone and the native 11-cis-retinal which could be compared to literature values.…”