Ionization in the track of a high-energy electron in liquid cyclohexane; pulse radiolysis of solutions of biphenyl in cyclohexane

Abstract

In order to study the ionization in the track of a high-energy electron in liquid cyclohexane, the lifetime distribution of the charged species is considered, with and without solutes present that can react with the species and change their mobility. Calculations of the lifetime distributions of the ions are presented, which have been made on the basis of the assumption that the precursors of the ion scavenging reactions can be considered as classically diffusing ions, initially present as pairs of oppositely charged species in each other's field. The calculations are compared with the lifetime distributions of biphenyl ions in solutions of biphenyl in cyclohexane with and without other solutes present, as determined by nanosecond pulse radiolysis. It is concluded that the precursor of the positive biphenyl ion is a positive species, which is considerably more mobile than a molecular ion.

Radiation Chemistry of Organic Liquids: Saturated Hydrocarbons

“…2.1 High mobility cations. Ionization of several cycloalkane liquids -cyclohexane, methylcyclohexane, trans-decalin and cis-decalin -produces cations whose drift mobilities are 5to-25 times greater than the mobilities of normally-diffusing molecular ions and (in some cases) thermalized electrons in these liquids [4][5][6][7][8]. These high-mobility cations are shown to be cycloalkane solvent holes with unusually long natural lifetimes (0.2 µs to 5 µs).…”

“…From conductivity studies, it is known that the cycloalkane holes rapidly react with various solutes, typically by electron or proton transfer [7][8][9][10][11][12][13][14][15][16][17][18][19]. These scavenging reactions establish the identity of the high-mobility cations as the solvent holes: Rapid generation of aromatic radical cations (A^+) in reactions of the holes with aromatic solutes (A) was observed using pulse radiolysis -transient absorption spectroscopy [4,5,6,20,[23][24][25] and, more recently, using pulse-probe laser-induced dc conductivity [26]. Rapid decay of the conductivity and transient absorbance signals from the cycloalkane holes was also observed .…”

Radiation chemistry of organic liquids: Saturated hydrocarbons

“…These scavenging reactions establish the identity of the high-mobility cations as the solvent holes: Rapid generation of aromatic radical cations (A^+) in reactions of the holes with aromatic solutes (A) was observed using pulse radiolysis -transient absorption spectroscopy [4,5,6,20,[23][24][25] and, more recently, using pulse-probe laser-induced dc conductivity [26]. Rapid decay of the conductivity and transient absorbance signals from the cycloalkane holes was also observed .…”

“…Ionization of several cycloalkane liquids -cyclohexane, methylcyclohexane, trans-decalin and cis-decalin -produces cations whose drift mobilities are 5-to-25 times greater than the mobilities of normally-diffusing molecular ions and (in some cases) thermalized electrons in these liquids [4][5][6][7][8]. These high-mobility cations are shown to be cycloalkane solvent holes with unusually long natural lifetimes (0.2 µs to 5 µs).…”

Optical study of electrons and positive ions in pulse-irradiated liquid 3-methyloctane at low temperatures

“…Efect of Elecirorz S c a~ engrrJ o~; Yields of R H f Our estimated in~tial yselds of RH ' and e,-are higher and loner, respectively, in the presence of SF, or CCI, than in pure 3-MO (Table I) Scavenging of the quasi-free electron, [7], increases the yield of RH' by decreasing the amount of [6], and of course decreases [ 5 ] also. Another possible explanation is that in pure 3-MO some recombination between RH' and e,-takes place by tunnelling at very short times (24), such that our extrapolation procedure for estimating initial yields is not valid Added SF, or CCl, would interfere with this recombination by scavenging e,-and hence giving increased yields of RH' at our first observation times.…”