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Propylene, excited state

Absorption due to main intermediates such as polymer cation radicals and excited states, electrons, and alkyl radicals of saturated hydrocarbon polymers had not been observed for a long time by pulse radiolysis [39]. In 1989, absorption due to the main intermediates was observed clearly in pulse radiolysis of saturated hydrocarbon polymer model compounds except for electrons [39,48]. In 1989, the broad absorption bands due to polymer excited states in the visible region and the tail parts of radical cation and electrons were observed in pulse radiolysis of ethylene-propylene copolymers and the decay of the polymer radical cations were clearly observed [49]. Recently, absorption band due to electrons in saturated hydrocarbon polymer model compounds was observed clearly by pulse radiolysis [49] as shown in Fig. 2. In addition, very broad absorption bands in the infrared region were observed clearly in the pulse radiolysis of ethylene-propylene copolymers [50] as shown in Fig. 3. Radiation protection effects [51] and detailed geminate ion recombination processes [52] of model compounds were studied by nano-, pico-, and subpicosecond pulse radiolyses. [Pg.556]

By media variables we mean the solvent, electrolyte, and electrodes employed in electrochemical generation of excited states. The roles which these play in the emissive process have not been sufficiently investigated. The combination of A vV-dimethylformamide, or acetonitrile, tetra-n-butylammonium perchlorate and platinum have been most commonly reported because they have been found empirically to function well. Despite various inadequacies of these systems, however, relatively little has been done to find and develop improved conditions under which emission could be seen and studied. Electrochemiluminescence emission has also been observed in dimethyl sulfite, propylene carbonate, 1,2-dimethoxyethane, trimethylacetonitrile, and benzonitrile.17 Recently the last of these has proven very useful for stabilizing the rubrene cation radical.65,66 Other electrolytes that have been tried are tetraethylam-monium bromide and perchlorate1 and tetra-n-butylammonium bromide and iodide.5 Emission has also been observed with gold,4 mercury,5 and transparent tin oxide electrodes,9 but few studies have yet been made1 as to the effects of electrode construction and orientation on the emission character. [Pg.438]

Ethylene-propylene copolymer films gave a very broad absorption in the visible region upon electron-pulse irradiation (Fig. 16) [93], It was comprised of at least three species, electrons, excited states, and alkane radical cations. At about 700 nm and 800 nm the contributions from excited states and radical cations, respectively, were largest. The lifetime of the radical cation determined... [Pg.70]

Since rapid reaction is expected and found between oxygen and molecules excited to their triplet state (i.e., 0.01 mm. oxygen has a marked effect) a less pronounced effect, such as is observed with 2-pentanone, may naturally be ascribed to a reaction with excited singlet states. The evidence is not conclusive, but the addition of 560 mm. oxygen to 2-hexanone at room temperature using 3130 A. radiation resulted in only a slight decrease in the acetone and propylene yields, so that Brunet and Noyes2 concluded that an excited triplet state was not involved in the type II process. Recent evidence from other sources seems to support this point of view. (Editor s Note Added in Proof However, a recent article by Ausloos and Rebbert [J. Am. Chem. Soc., 86, 4512(1964)] indicated that the type II process occurs via a triplet excited state.)... [Pg.112]

The solvation dynamics of Coumarin 133 in propylene carbonate has been studied by Barbara and cowoikers by femtosecond fluorescence spectroscopy.(151 This solute has a large charge redistribution in the excited state, and solvation is dominated by the dielectric response of the solvent to the new change distribution. We... [Pg.303]

Fig. 18. Values of the kc jk-i ratio (evaluated from the experimental efficiencies of formation of the excited state) as a function of the solvent longitudinal relaxation time Ti. Data for 4-(9-anthryl)-V,V,3,5-tetra-methylaniline in acetonitrile (ACN), pro-pionitrile (PN), butyronitrile (BN), propylene carbonate (PC), sulfolane (TMS) and 7-butyrolactone (BL) solutions. Adapted from [153]. Fig. 18. Values of the kc jk-i ratio (evaluated from the experimental efficiencies of formation of the excited state) as a function of the solvent longitudinal relaxation time Ti. Data for 4-(9-anthryl)-V,V,3,5-tetra-methylaniline in acetonitrile (ACN), pro-pionitrile (PN), butyronitrile (BN), propylene carbonate (PC), sulfolane (TMS) and 7-butyrolactone (BL) solutions. Adapted from [153].
In order to compare ab initio SOS/CIS with TDHF calculations we have evaluated the SFG response of two model chiral compounds, R-(- -)-propylene oxide and R-mono-fluoro-oxirane. The computed excited state energies have all been down-shifted by 2.675 eV for R-(- -[-propylene oxide (and 2.27 eV for R-mono-fluoro-oxirane) [59]. Figure 5 shows that both methods calculate very similar magnitudes and dispersions of the SFG pseudoscalar. [Pg.373]

Photolysis.—Photochemical transformations of thietan derivatives have not received much attention, but it appears that the initial process is homolysis of a C—S bond, and that extrusion of sulphur is not important, in contrast to the case for thiirans. A reversed [2 + 2]cycloaddition may occur via initial homolysis of the C—S bond, 2,2-diphenyl-3,3-dimethyl-4-isopropylidenethietan, for example, giving l,l-diphenyl-2,2-dimethyl-ethylene, and rra j-2-phenyl-3-benzoylthiiran being converted into a mixture of cis- and /mns-benzalacetophenone, probably by way of its triplet excited state. Thietan vapour on photolysis gave mixtures containing ethylene, propylene, and polymer, and on prolonged irradiation, 2-methylthiiran. ... [Pg.114]


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See also in sourсe #XX -- [ Pg.118 ]




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Propylene, excited state reactions

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