George Bakale

Excess electrons and positive charge carriers in liquid ethane

Measurements of excess electron drift velocity as a function of the electric field were carried out up to field strengths of 280 kV/cm at temperatures from 111 to 216°K. Low field mobilities were obtained and at higher field strength the drift velocity increased more than proportionally with the field. The data are discussed on the basis of the trapping model, and thermally activated hopping is assumed for the motion. The jumping length as a function of the temperature was obtained from the high field data. The positive charge carrier seems to be of ionic nature and the mobility follows Waldens rule.

Dissociative Attachment of Thermal Electrons to N2O and Subsequent Electron Detachment

The attachment of electrons to nitrous oxide has been studied, following pulse ionization, by a microwave conductivity technique. For pure N2O, and N2O diluted with N2, extrapolation of the experimentally observed attachment rate constant to zero pressure gives an upper limit of 1 × 10−15 cm3 molecule−1 · sec−1 for the rate constant for two‐body attachment at 298°K. When C2H6 or C2H8 are used as diluents a higher two‐body rate constant of 6× 10−15 cm3 molecule−1 · sec−1 is found which is believed to represent the rate constant of the dissociative attachment reaction e−+N2O→N2+O−. The much lower value for pure N2O or N2O–N2 mixtures is explained by the regeneration of electrons, via the reactions O−+N2O→NO+NO− and NO−+N2O→NO+N2O+e−, which largely nullifies the primary attachment step. The presence of a hydrocarbon prevents electron regeneration by irreversibly reacting with O− and allows observation of the uncomplicated rate constant for dissociative attachment. The rate constant for dissociative attachmen...

Decay of Quasifree Electrons in Pulse‐Irradiated Liquid Hydrocarbons

The decay of the ion current in pulse‐irradiated hydrocarbons in a parallel‐plate ion chamber has been observed in the nsec‐μsec time range during which time the major contribution to the ion current is the quasifree, high mobility electron. At dose rates of 1015 eV cm−3/10−8 sec the electron current decay is exponential with a half‐life ranging from ∼5 nsec (cyclopentane) to >400 nsec (n‐hexane). At higher dose rates, however, deviation from the exponential decay occurs and second‐order decay is approached at the highest doses/pulse (6.5× 1016 eV‐cm−3/10−7 sec) studied. This change from pseudo‐first‐order to second‐order kinetics is interpreted as a change in the electron decay from an attachment type process to electron‐ion recombination. Absolute rate constants for the electron reacting with several solutes in n‐hexane were also determined; these are ks(e−+CCl4) = ks(e−+φ2)=1.0± 0.1× 1012, ks(e−+I2)=2± 1× 1011, ks(e−+H2O)≃ ks(e−+benzene) ≤ 1× 109, and ks(e−+O2, CO2, N2O, SF6) ≤ 2× 108M−1· sec.−1

Electron transport in mixtures of liquid methane and ethane

The mobility of excess electrons in liquid mixtures of methane and ethane was measured over the entire range of composition at T=111 °K. Field dependent mobilities were observed at higher field strengths. The data are discussed on the basis of the quasifree and localized electron models.

Effect of an Electric Field on Electron Attachment to SF6 in Liquid Ethane and Propane

Abstract The effect of an external electric field, E, on the electron attachment rate constant, ke, of SF6 was studied by a pulsed-conductivity technique in liquid ethane and propane at temperatures ranging from 133-176 K and 156-216 K, respectively. At constant temperature, ke was independent of E at fields less than Ec , the critical field above which the mobility becomes field-dependent, but at E> Ec, ke increased proportionally with De, the diffusion coefficient of the electron. Application of diffusion-controlled reaction theory to the ke - De dependence yielded an effective encounter radius of 14.5 Å for the e--SF6 reaction pair in both liquids. This encounter radius is discussed in terms of the electron-SF6 interaction energy and models of electron transport and attachment in low-mobility liquids.