PHOTOCURRENTS IN NEAT METHANE AND ETHANE

Photocurrents appear in neat liquid methane for photon energies hv>11. 3 eV. In neat ethane gas, the photoconductivity threshold decreases wi th density rho from 11.5 eV at rho=3X10(16) cm(-3) to 10.85 eV at rho= 2.2X10(21) cm(-3). It continues to decrease, though more slowly, in th e liquid. Moreover, in liquid C2H6 an increase in the field strongly e nhances the photocurrent, the degree of enhancement depending on the p hoton energy. No such enhancement was observed in liquid methane. The results are discussed with reference to known values of excess electro n energies V-0 and electron mobilities mu(e), and in view of recent si mulation results [L. Liu and B.J. Berne, J. Chem. Phys. 99 (1993) 9054 ] on electron solvation in both substances.