PHOTOINJECTION OF EXCESS ELECTRONS INTO LIQUID HYDROCARBONS - A THERMODYNAMIC TREATMENT

A photocathode immersed in an insulating liquid might inject electrons . The analysis of the wavelength versus photocurrent curve enables one to evaluate the energy of the injected, quasi-free electron in the li quid, i.e. the bottom of the conduction level V-0 The pressure depende ncies of V-0 observed with several liquid hydrocarbons indicate certai n discrepancies between experimental data and theoretical expectations . Thermodynamic analysis shows that, contrary to theoretical descripti ons, the injection proceeds via a polytrope which runs between the iso thermal-isochoric and isoentropic-isobaric curves. This being attribut ed to local perturbations of temperature and pressure by the injection process, an estimate of the time scale of injection can be given, fin ding characteristic times to be in the order of 0.01-0.1 ps. (C) 1998 Elsevier Science S.A. All rights reserved.