Ketyl-phenoxyl triplet radical pair in glycerol: Magnetic field effect and cage kinetics in terms of the two-state model.

The geminate recombination kinetics of the triplet pairs of neutral radicals formed as a result of hydrogen atom transfer from 4-methylphenol to 4,4'-dimethylbenzophenone in the triplet excited state was studied by laser flash photolysis in the temperature range of 263-323 K. The pair included aromatic ketyl and 4-methylphenoxyl radicals produced in a viscous (∼10 P) solution of the initial reagents in glycerol. The geminate recombination kinetics demonstrate a "tail" c(t) ∼ 1/t, with contribution of magnitude A, which increases with temperature.

Photoinduced Reactions of Benzophenone in Biaxially Oriented Polypropylene.

The photoinduced reactions of benzophenone (B) in biaxially oriented polypropylene (BOPP) were studied with nanosecond laser photolysis (N laser, λ337.1 nm). The first observed transient was a triplet state B*.

Reactivity of Benzophenone Ketyl Free Radicals in an Elongated Elastomer Film.

The effect of polymer film elongation leading to the thinning of the film up to three times on the decay of transients was studied. Kinetics of benzophenone (B) triplet state (3)B* and ketyl free radical BH• in soft rubber poly(ethylene-co-butylene) (abbreviated as E) was investigated by nanosecond laser flash photolysis. We monitored decay kinetics of the triplet state of (3)B* and of BH• decay in the polymer cage and decay of BH• in the polymer bulk.

Kinetics of photochemical reactions of biphotochromic compounds based on spironaphthopyran and enamine--conjugation effect.

A novel biphotochromic compound (BPC) with two photochromic fragments, namely spironaphthopyran and hydroxyazomethine, was synthesized and studied by nanosecond laser flash photolysis using the excitation wavelengths of 337, 430, 470 and 500 nm in methanol and toluene. The photoexcitation of BPC results in the formation of at least two colored transients. The first one is the merocyanine form B (the maximum in the absorption spectrum is near 600 nm and the lifetime is 0.

Kinetics of benzophenone ketyl free radicals recombination in a polymer: reactivity in the polymer cage vs. reactivity in the polymer bulk.

The decay kinetics of intermediates produced under photolysis of benzophenone (B) dissolved in soft rubber poly(ethylene-co-butylene) films (abbreviated as E) was studied by ns laser flash photolysis in the temperature range of 263-313 K. We monitored decay kinetics of the triplet state of (3)B* and of benzophenone ketyl free radical BH˙. The fast exponential decay of (3)B* (life-time τT ≈ 200 ns) is accompanied by hydrogen atom abstraction from E with a formation of BH˙ and a polymer free radical R˙.

Decay kinetics of benzophenone triplets and corresponding free radicals in soft and rigid polymers studied by laser flash photolysis.

The kinetics of transients formed under photoexcitation of benzophenone (B) dissolved in three different polymers was studied by ns laser flash photolysis. These polymers were the soft rubbers poly (ethylene-co-butylene) (EB), polystyrene block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) and hard polystyrene (PS). We monitored the decay kinetics of triplet state (3)B(*) and of ketyl radicals BH(●).

Laser flash photolysis of benzophenone in polymer films.

With a nanosecond laser we studied flash photolysis of benzophenone (BP) dissolved in four different polymer films. We measured kinetics of decay of a triplet state of benzophenone (3)BP as well as kinetics of decay of benzophenone ketyl free radicals BPH(•). Polymer matrices have plenty of reactive C-H bonds, and the hydrogen abstraction by (3)BP leads to a formation of geminate pair which either recombines into molecular products or dissociates.

Characterization of the composition of the aqueous humor and the vitreous body of the eye of the frog Rana temporaria L.

This study aimed to analyze the aqueous humor (AH) and the vitreous body (VB) of the eye of the adult frog Rana temporaria L. as a representative species of amphibians, which lead a semi-terrestrial life. The presence of collagen, albumin, uric acid and electron donors was shown in both media; however, there are slight differences in their concentrations.