Abstract

Optical second harmonic generation is intrinsically sensitive to the interface between two isotropic media. Static measurements of SH intensity determine, for example, surface symmetry and orientation of adsorbed species. Use of the technique as a real-time probe of interfacial processes requires an ultrafast pulsed laser system. The time dependence of the SH signal following charge injection by either a voltage step or optical pulse monitors interfacial processes such as electrochemical reactions, electron transfer, trapping in surface states, and charge recombination. These new time-resolved measurements potentially provide information about interfacial kinetics and dynamics in the nanosecond and faster time regimes. Among the semiconductors investigated are amorphous selenium thin films, isomorphic selenium-tellurium mixtures, and transition metal hexagonal layer compounds. These materials have practical consequences which range from optical switching candidates to semiconductor electrodes.

© 1986 Optical Society of America