Kinetics of the γ-ray induced decoloration of solutions of α, α′-diphenyl picryl hydrazyl in chloroform and carbon tetrachloride

Ciborowski, S.; Colebourne, N.; Collinson, E.; Dainton, F. S.

doi:10.1039/tf9615701123

Cited by 20 publications

(4 citation statements)

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“…Neben der normalen Verwendung als ((scavenger H und ccquencher H wurde Tetrachlorkohlenstoff verschiedenen strahlungschemischen Untersuchungen unterworfen, um sein Verhalten unter dem Einfluss ionisierender Strahlung zu klaren. So sind beispielsweise Arbeiten bekannt [l] [a] [3], die Angaben uber die Ausbeute an abfangbaren Radikalen im reinen Tetrachlorkolilenstoff geben (die G-Werte l ) schwanken zwischen 2 , 3 undl9), oder Arbeiten mit Angaben iiber die Produkt-Zusammensetzung (G(C1,) g G(C,Cl,) 0 3.5. Die Ultraviolett-Absorptionsbanden.…”

Section: Pulsradiolyse Organischer Halogenverbindungen I Nachweis Kuunclassified

Pulsradiolyse organischer Halogenverbindungen I. Nachweis kurzlebiger Charge‐Transfer Komplexe mit Chloratomen

Bühler

1968

Helvetica Chimica Acta

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Szmwmwy. I n a solution of benzene in carbon tetrachloride a transient absorption in the visible part of the spectrum could be detectcd. It appears within less than 0.3 ps after the irradiation by a high-energy electron pulse, and it can be shown to bc due to the charge-transfer complex between the chlorine atoms as electron acceptors and benzene molecules as electron donors. A variety of aromatic hydrocarbons also yield similar absorption bands in the visible. They show a linear correlation between the absorption energy and the ionisation potential of the aromatic molecules, which is typical for charge-transfer complexes. A minimum value for the equilibriuin constant of complex formation is given. The equilibrium is almost fully shifted to the complex side. An estimated G value for the charge-transfer complex indicates that the complex is actually part of a main reaction in the radiation-induced mechanism. The decay of the charge-transfer complex is mostly pseudo-first order with a half life of a few microseconds.

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Section: Pulsradiolyse Organischer Halogenverbindungen I Nachweis Kuunclassified

Pulsradiolyse organischer Halogenverbindungen I. Nachweis kurzlebiger Charge‐Transfer Komplexe mit Chloratomen

Bühler

1968

Helvetica Chimica Acta

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“…The situation appears to be analogous to that of DPPH in chloroform or carbon tetrachloride. 31 On a stationary state analysis the following reaction scheme:…”

Section: N O N -G a S E O U S Product I D E N T I F I C A T I O N A N...mentioning

confidence: 99%

Beta-radiolysis of liquid benzene

Cherniak¹,

Collinson²,

Dainton³

1964

Trans. Faraday Soc.

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Various methods have been used, including the chromatographic analysis of non-gaseous products and free radical detection with ferric chloride, to investigate the mechanism of the gOSr----!JOY beta-radiolysis of liquid benzene. The initial G for reduction of FeCl3 is strongly dependent on [FeCI3] and may be as high as 10; it falls rapidly with increasing dose to a constant value of 0866012. It is concluded that the most important primary act leads to the formation of phenyl radicals and hydrogen atoms, together with electronically excited benzene molecules of two types, one with a lifetime of -100 psec tentatively assigned to the 3Blu state and the other, of shorter life, which may be the lBzu state. The C6H5 radicals and H atoms are very reactive towards benzene, and FeC13 scavenges only secondary, less reactive, radicals but can also be decomposed by interaction with a benzene molecule in either state of excitation.Whereas hydrogen and acetylene are the only gaseous products in the radiolysis of liquid, air-free benzene,l-3 the non-gaseous products, often termed " polymer", have been only partially characterized. Gordon, van Dyken and Doumani 3 have shown that the " polymer ", obtained from the W o -y irradiation of benzene, contains a Clz fraction which constitutes 18.8 % w/w of total "polymer", a C18 fraction (57.6 %) and a >CIS fraction (23.6 %). Although biphenyl was the only C12 product positively identified 3 (cf. ref. (4)), four other members of the Cl2 group have been distinguished 5 ; two were positively identified as phenyl cyclohexadiene-2,4 and phenyl cyclohexadiene-2,5, a third is probably phenyl hexatriene and the fourth was not identified. The identity of the c 1 8 and > C18 products is even less certain. There appear to be a large number of CIS products 5 and this fraction may contain " hydrogenated terphenyls and terphenyls ". 3 Values of G(H2), G(C2H2), G(diphenyl), and G(benzene+" polymer "), obtained by several workers, are presented in table 1.

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“…The curvature of this line seems to imply that the rate of reaction (5) has a greater than first-order dependence on [S] in this region. This may be due to the highly directional propagation of the exciton combined with the possible location of the first solute molecules in lattice positions remote from the exciton pathway, so that reaction (5) does not occur to any considerable extent until most of the uiifavourable sites have been occupied. Above the concentration at which this occurs, which for benzene is about 200 pM, any additional solute molecules must occupy sites at which reaction (5) will occur.…”

Section: Shape Of the G(-s) Against Is] Curvesmentioning

confidence: 99%

Phase change and energy transfer effects in the radiation chemistry of organic substances

Collinson¹,

Conlay²,

Dainton³

1963

Discuss. Faraday Soc.

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G(-S)values, where S = FeC13 or I2 or DPPH for solutions of S in various organic solvents, have been measured at different temperatures in the range -196-30°C. For all systems in the liquid or glassy solid phases, [S] diminishes linearly with dose, and G(-S) is largely independent of IS] and temperature (provided the phase is not changed), being larger in the liquid than the glass. Crystalline solid solutions fall into two categories. Type-A systems, comprising solutions of FeC13 in diethyl ether or 1,4-dioxan, or DPPH in benzene or diphenyl ether, are similar to glasses.Type-B systems, comprising solutions of FeC13 in benzene, diphenyl ether, diphenyl methane and phenetole (crystalline state only), and I 2 in diphenyl ether, give steeply curved [S]-dose graphs and G(-S)o increases proportionately with increase of [S], the slope of this line being larger the lower the temperature. Thus values of G( -S)O for the solid phase may be much larger than G( -S) for the liquid or glassy phases (in benzene at -196" this factor can be as large as 30), and there is a sudden increase of G( -S)o on freezing.Reasons are given for believing that the reaction occurs whilst the system is solid and that in class-B systems the radiation induces formation of excitons corresponding to the molecular state 1B2u (for benzene), which are propagated over distances of 50-100A. Interaction of these with solutes whose absorption spectrum overlaps the exciton spectrum causes chemical change of the solutes. Class-A crystals cannot form excitons in the appropriate spectral range. That crystallinity is essential for class-B behaviour is shown by the grossly disparate results for those systems which show class-B behaviour when crystalline and class-A behaviour, at the same temperature and solute concentration, when they are in either the supercooled liquid or glassy states. Other observations are recorded and explained on the same hypothesis.

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Kinetics of the γ-ray induced decoloration of solutions of α, α′-diphenyl picryl hydrazyl in chloroform and carbon tetrachloride

Cited by 20 publications

References 0 publications

Pulsradiolyse organischer Halogenverbindungen I. Nachweis kurzlebiger Charge‐Transfer Komplexe mit Chloratomen

Pulsradiolyse organischer Halogenverbindungen I. Nachweis kurzlebiger Charge‐Transfer Komplexe mit Chloratomen

Beta-radiolysis of liquid benzene

Phase change and energy transfer effects in the radiation chemistry of organic substances

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