Photodecomposition internal

Chlorine atoms and other chlorine species formed by photodecomposition of carbon tetrachloride in the stratosphere can catalyze reactions that destroy ozone. As the manufacture of carbon tetrachloride for use in chlorofluorocarbons is phased out according to a recent international agreement (EPA 1987e), the impact of carbon tetrachloride on atmospheric ozone is likely to decrease. 

The photodecomposition of perfluoro diethyl-62 and perfluoro-di-w-propyl63 ketones has been shown to follow a course similar to that of hexa-fluoroacetone. The fluorescence is weaker in the case of the perfluoro-diethyl ketone and almost absent in the case of the perfluorodi-n-propyl ketone, and the pressure dependence of the quantum yields of carbon monoxide is consistent with this behavior. It is proposed that in the more complex structures, the energy may more easily be accommodated and lost by internal conversion, thereby reducing the contribution made by fluorescence and by Collisional quenching of the excited molecule. 

H. Kusajima, and R. Ishida, Photodecomposition of Gatifloxacin (AM-1155) and its related drugs, and their phototoxic potency in guinea pigs, in 20th International Congress of Chemotherapy, Sydney, Abstract No. 5318, 1997. 

In the photodecomposition of H20 at the water-rutile Ti02 interface, the primary intermediates of 02 evolution can be investigated by multiple internal reflection IR absorption and PL. On the basis of spectroscopic data, Nakato et al. (Nakamura and Nakato, 2004) proposed a reaction mechanism in which 02 photoevolution is initiated by nucleophilic attack of H20 on a photogenerated hole at a surface lattice O site, and not by oxidation of a surface OH group by a hole. In the case of a photoetched... 

In summary, glyoxal photodecomposition studies are still in a state of disarray. A complete accounting of the photolysis products is necessary before definite conclusions can be drawn. Very low pressure work where —/vvv- -So internal conversion is... 

Mallouk and co-workers [6, 26, 206] reported the photodecomposition of acidic KI to H2 and iodine under visible light irradiation. For this purpose, IQNbeOn was internally loaded with Pt, ion exchanged partially with acid to obtain K4 jcHj Nb60i7 /JH2O (x 2.5) and then sensitized with RuLs (L = 4,4 -dicarboxy-2,2 -bipyridine). It was found that KI is the best reactant among the alkali metal iodides (Figure 16). 

Photodecomposition of maleic anhydride in the gas phase has been reported to give ethylene, carbon dioxide, and carbon monoxide. The fragmentation is believed to proceed via internal conversion to a vibrationally excited ground state. Photoeiimination of carbon dioxide has also been observed in perfluoro-n-butanoic anhydride and in perfluorosuccinic anhydride to give tetra-... 

Phases in the polymer. Semicrystalline polymer films of poly(ethylene terephthalate), poly(ethylene-2,6-naphthalate) and poly(phenylenesulphide), which are stressed biaxially or monoaxially, always show a wavy surface structure (Fig. 9.7) of the order of 1-50 pm after ablative photodecomposition, whereas amorphous films of these polymers produce a smooth surface. It has been suggested that this behaviour is correlated with the amorphous and crystalline areas in the polymer [137, 1302, 1602] or is influenced by the internal stress field from the stretching operation [164]. 

Maricq and Szente (1995) used time resolved IR and UV spectroscopy to study the photodissociation of CF3C(0)C1 in photolysis at 193 and 248 nm. They concluded that the net reaction shown by process (III) described the results best rapidly dissociating CF3CO and/or COCl radicals presumably were present as intermediates. At 193 nm the CO is formed with extensive internal excitation (TVib = 3, 800 900 K), whereas at 248 nm it is formed predominantly in v = 0. Quantum yields of the photodecomposition were measured by comparing yields of HCl (formed in experiments with added ethane) and RO2 (experiments with added O2) from CF3C(0)C1 to those from the photodisssociation of CH3CI at 193 nm and CI2 at 248 nm they assumed the latter two species have unit photodissociation efficiencies. Values of the total quantum yield of photodecomposition, ((/>i -t- + < ) = 1.10 0.11 at 193 nm and 0.92 ... 

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