Heavy Ion Radiolysis of Cyclopentane

Wojnárovits, László; LaVerne, Jay A.

doi:10.1021/j100028a033

Cited by 7 publications

(5 citation statements)

References 5 publications

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“…This trend can be observed for the iodobenzene formation for carbon ions at high iodine concentrations, see Figure . Similar results are observed for parent radical formation in cyclic alkanes. − It can also be observed for γ-rays, protons, and helium ions that at the highest iodine concentrations essentially all phenyl radicals have been scavenged, but the biphenyl yield is not zero. For all of the radiations used here, the biphenyl radical yield never decreases below a value of about 0.075 molecule/100 eV, as shown by the dotted line in Figure .…”

Section: Resultssupporting

confidence: 71%

“…The lower yields for iodobenzene with carbon ions can be attributed to faster radical chemistry or lower initial radical yields. Decreasing radical yields with increasing LET were observed with cyclic alkanes. − Carbon ions of 10 MeV energy have a track average LET o of 686 eV/nm compared to the 0.2 eV/nm for γ-rays. Radical−radical reactions are enhanced in carbon ion tracks because of the increase in local radical concentrations .…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, a thorough examination of its chemistry would give a significant amount of information on the radiolysis of liquid benzene. Iodine scavenging techniques have successfully examined primary radical formation in cyclic alkanes − and more recently in the γ-radiolysis of benzene . These techniques are expanded in this work to include different types of radiation in order to provide fundamental information on the fate of the phenyl radical in the radiolysis of liquid benzene.…”

Section: Introductionmentioning

confidence: 99%

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Heavy Ion Radiolysis of Liquid Benzene

LaVerne

Araos

2002

J. Phys. Chem. A

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The mechanisms responsible for the main products in liquid benzene radiolysis (biphenyl, molecular hydrogen, and phenyl radical) are probed with protons, helium ions, and carbon ions of a few to 30 MeV energy. Phenyl radical yields have been examined using iodine scavenging techniques. The results are combined with similar data for γ-rays and suggest that phenyl radicals mainly react with benzene to give a long-lived adduct, which leads to polymer formation. Iodine can react with this adduct to give enhanced yields of biphenyl. Biphenyl is the predominant single hydrocarbon product in the radiolysis of neat benzene with a yield of 0.075 molecule/100 eV. Its yield is nearly independent of radiation type and energy suggesting that its formation in neat benzene is due to a fast ion−molecule process and not due to phenyl radicals. The total yield of 0.7 radicals/100 eV is almost entirely due to phenyl radicals and H atoms. A reexamination of the fluorescence from the singlet excited state of benzene suggests that this state is the precursor for molecular hydrogen and acetylene, whereas the triplet excited state decays to phenyl radicals and H atoms. Most of the excited states formed in the γ-radiolysis of benzene seem to decay to ground without formation of any product.

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Section: Resultssupporting

confidence: 71%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Heavy Ion Radiolysis of Liquid Benzene

LaVerne

Araos

2002

J. Phys. Chem. A

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“…The effect of LET and ion track structure in radiation chemistry has been examined in the heavy ion radiolysis of various saturated hydrocarbons. ,− Few products are formed in liquid cycloalkanes and analysis of their yields can lead to estimates of the relative ratio of triplet to singlet excited-state formation. For instance, the observed ratio of the triplet to singlet excited-state formation in liquid cyclooctane radiolysis is 1.3 for fast electrons and increases to about 3.0 with increasing LET.…”

Section: Introductionmentioning

confidence: 99%

Heavy Ion Radiolysis of Liquid Pyridine

2006

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The radiation chemical yields of the main products produced in liquid pyridine radiolysis (molecular hydrogen and dipyridyl) have been examined as a function of particle linear energy transfer (LET) with protons, helium ions, and carbon ions of a few to 30 MeV and compared to gamma-radiolysis published in a previous work (J. Phys. Chem. A 2005, 109, 461). Anthracene and biphenyl scavenging techniques have been used to clarify the role of the triplet excited state. An increase in triplet scavenger concentration leads to a decrease in pyridine triplet excited state with a concurrent decrease in dipyridyl, but formation of the latter does not primarily involve pyridyl radicals expected to be produced in the decomposition of the triplet excited state. A decrease in the yield of dipyridyl and an increase in molecular hydrogen are observed with increasing track average LET. The dipyridyl yield with 10 MeV carbon ions is 0.20 molecules/100 eV, which is only 16% of that of observed with gamma-rays. The low yield of dipyridyl with carbon ions is attributed to intratrack triplet-triplet (T-T) annihilation processes due to the increase in local triplet excited-state concentrations with increasing LET. An increasing yield of molecular hydrogen with increasing LET is probably due to an increase in the formation and subsequent decay of singlet excited states produced by the T-T annihilation. A complete mechanism for the radiolysis of liquid pyridine is presented.

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“…Furthermore, following the generation of iodine molecules (I 2 ), the polymerization was inhibited. [39][40][41] For the emerging I 2 that was not consumed thoroughly, there existed a long induction period in this step. Consequently, the degradation of iodine end groups and the emergence of I 2 led to low conversion and low DP of PVAc.…”

Section: Papermentioning

confidence: 99%