Study of ?/? ratios of organic scintillation solutions

Berlman, Isadore B.; Grismore, R.; Oltman, B.G.

doi:10.1039/tf9635902010

Cited by 18 publications

(15 citation statements)

References 3 publications

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“…A similar quenching mechanism was previously reported by Berlman and coworkers. 7 With increasing LET the density of radicals and other transient species in the track increases. Since the lifetime of the benzene excited state is long, about 27 ns, 19,20 there is a high probability that it will survive long enough to undergo second-order reactions in the particle track.…”

Section: Resultsmentioning

confidence: 99%

“…Irradiations were performed with 1 H, 4 He, 7 Li, and 12 C ions using the 10-MV FN Tandem Van de Graaff accelerator of the Notre Dame Nuclear Structure Laboratory. 25 The window assembly and emission detection are shown in Figure 1.…”

Section: Methodsmentioning

confidence: 99%

“…A few investigations have used this technique in the heavy ion radiolysis of hydrocarbons. [6][7][8][9][10][11][12][13][14] Although it is difficult to interpret detailed track structure from these experiments because one is observing both ionic and excited state transients, they are important for an overview of the processes in heavy ion tracks. All of the studies find a decrease in emission with increasing LET.…”

Section: Introductionmentioning

confidence: 99%

“…The observation of emission from aromatic compounds added to hydrocarbons is a well-established technique for examining radiolytic products. , Emission from the solute represents both ionic and excited state processes of the medium. A few investigations have used this technique in the heavy ion radiolysis of hydrocarbons. − Although it is difficult to interpret detailed track structure from these experiments because one is observing both ionic and excited state transients, they are important for an overview of the processes in heavy ion tracks. All of the studies find a decrease in emission with increasing LET.…”

Section: Introductionmentioning

confidence: 99%

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Fluorescence in the Heavy Ion Radiolysis of Benzene

LaVerne

1996

J. Phys. Chem.

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Fluorescence emission has been measured in the radiolysis of neat liquid benzene with 1-15 MeV protons, 5-20 MeV helium ions, 5-30 MeV lithium ions, and 10-30 MeV carbon ions using single photon counting techniques. Companion studies were performed with 90 Sr-90 Y -particles with an average energy of about 1.66 MeV. Within 30-50 ns following the passage of the heavy particles the fluorescence intensity decreases rapidly and then levels off to a much slower decay rate which is very nearly the same for -particles and high-energy protons and helium ions. The lifetimes of both the fast and slow components of the fluorescence decrease with increasing linear energy transfer (LET), and the magnitude of the fast component increases with respect to the slower one. Quenching of the fluorescence by radicals or other transient species produced in the particle track are thought to be responsible for the observations. At low LET the relative yield of the fluorescence decreases with increasing LET, presumably due to the quenching. However, at higher LET the fluorescence yield increases with increasing LET. Self-annihilation reactions of the triplet states to give singlet states may be the source of these observations. These experiments are the first in which the temporal variation of fluorescence emission has been determined in a neat hydrocarbon liquid irradiated with heavy ions.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fluorescence in the Heavy Ion Radiolysis of Benzene

LaVerne

1996

J. Phys. Chem.

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“…4,[6][7][8]12 However, the present results suggest that these reactions are negligible with PPO solutions. The greater proportion of triplet state formation in high LET tracks has to be taken into account; one can estimate a reduction in the total luminescence by a factor of ∼2.…”

Section: Discussionmentioning

confidence: 72%

Magnetic Field Effects on the Solute Luminescence of Alkane Solutions Irradiated with Heavy Ions

LaVerne

Brocklehurst

1996

J. Phys. Chem.

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The effects of track structure on the luminescence decays in cyclohexane and in 2,2,4-trimethylpentane (isooctane) solutions of 2,5-diphenyloxazole (PPO) have been determined in the presence and in the absence of an external magnetic field. Irradiations were performed with protons of 1-15 MeV and with helium ions of 2-20 MeV energy. Companion studies were performed with 90 Sr-90 Y -radiolysis. The magnetic field effect is due to the hyperfine interaction of nuclear spins in the geminate pair of solvent radical ions produced. In both solvents, the effect of the magnetic field on luminescence decreases with increasing linear energy transfer (LET) from about 40% for -particles to only a few percent with helium ions. Magnetic field effects with protons decrease in time whereas they are constant with -particles. This result is attributed to the overlap of initially isolated spurs during the evolution of the proton track; the probability of nongeminate recombination increases with the number of neighboring ion pairs. The total luminescence intensity per incident particle remains constant with proton energy but increases slightly with increasing helium ion energy. At a given particle energy, the intensity is greater in cyclohexane than in isooctane. The pulse shapes of the luminescence decays reflect the distributions in ion recombination times, and very little variation in luminescence decay rates is observed with increasing LET. IntroductionEnergy deposited by the passage of ionizing radiation in hydrocarbons leads to a series of clusters of ions and excited states (spurs) stochastically placed along the particle path. 1 The spatial distribution of these species and the radicals that they form make up the particle track structure, and it is largely responsible for the observed yields of final products. Increasing the linear energy transfer (LET ) stopping power, -dE/dx) as in the case of proton, helium ion, or other heavy ion radiation increases the concentration of reactive species in the particle track, and intratrack radical-radical reactions can be preferred over radical diffusion into the bulk medium. For instance, in the fast electron radiolysis of cyclohexane almost 80% of the cyclohexyl radicals produced react in the bulk medium whereas less than 10% escape the tracks of low-energy carbon ions. 2 Almost all of the studies on the chemical effects of track structure have been made from observations of the final product formation. 3 Only a few studies have attempted to observe the formation of ions and excited states in the heavy ion radiolysis of hydrocarbons, 4-11 but it is well-known that scintillation yields decrease markedly with increasing LET. 12 Luminescence from aromatic compounds added to hydrocarbons has long been used to examine the radiolytic production of ions and excited states. 5,13 The initial ionization and direct excitation of the solvent and the subsequent reactions can be represented by RH -Df RH + + e -or RH* (R1)RH* + S f RH + S* (R3)where RH is the solvent and S is the solute. When moderat...

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6.3 Ratios of pulse heights at alpha- and beta-excitation

Schmillen¹,

Legler²

Luminescence of Organic Substances

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Study of ?/? ratios of organic scintillation solutions

Cited by 18 publications

References 3 publications

Fluorescence in the Heavy Ion Radiolysis of Benzene

Fluorescence in the Heavy Ion Radiolysis of Benzene

Magnetic Field Effects on the Solute Luminescence of Alkane Solutions Irradiated with Heavy Ions

6.3 Ratios of pulse heights at alpha- and beta-excitation

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