SELECTIVE HOLE CAPTURE BY SOLUTE MOLECULES IN GAMMA-IRRADIATED SEC-BUTYL CHLORIDE GLASSES AT 77-K

A sec-butyl chloride glass containing a pair of solutes was γ irradiated at 77 K and the yields of the solute cations were measured. For the solute pairs N,N-diethylaniline-biphenyl, pyrene-biphenyl, and benz[a]anthracene-naphthalene, the yield of the cation of the first solute, which is of lower ionization potential than its counterpart (the second solute), was found to be independent of the second-solute concentration. The logarithms of the second-solute-cation yields are linear in the first-solute concentration and a negative slope of the plot agrees with that of the plot of log (y10 - y1) vs. the first-solute concentration, where y1 is a yield of the first-solute cation and y10 is a constant. Plots of log (y20 - y2) against the second-solute concentration fit a straight line. These remarkable kinetic features were elucidated in terms of selective capture of a different state of holes by each solute. For benz[a]anthracene-pyrene and biphenyl-p-xylene pairs, the semilogarithmic plots do not hold, and the yield of each solute cation depends on the concentration of both solutes. In these cases two solutes capture holes competitively. The competitive capture is regarded as the special case of selective capture where the ionization potentials of two solute are equal or nearly so. © 1978 American Chemical Society.