A note on the temperature dependence of the yield and range of photoejected electrons from N,N,N′,N′-tetramethyl-p-phenylenediamine in 2,2,4-trimethylpentane

Abstract

The photocurrent of N,N,N′,N′-tetramethyl-p-phcnylcnediamine (TMPD) in 2,2,4-trimethylpentane (isooctane) excited at 5.90 eV has been studied as a function of temperature from 195 to 298 K both in the absence and presence of the electron scavengers n-perfluoroheptane and perfluoromethylcyclohexane. Using an exponential radial distribution function for geminate pair separation distances with range parameter corrected to accommodate its change with temperature, it is found that the photoejection quantum yield of TMPD is essentially independent of temperature from298 K to [Formula: see text] and then increases slightly [Formula: see text] on further cooling to 195 K. In the presence of electron scavengers there is a contribution to the magnitude of the range parameter from the action of the scavenger to pre-thermalize the epithermal electron. The temperature dependence of this contribution is analyzed and found to increase with decreasing temperature.