RESPONSE-TIME OF PHOTOEMISSION OF ULTRAFINE PARTICLE THIN-FILM

The response time of photoemissive materials is required for detecting ultrashort duration laser pulses. In this paper, the response time of photoemission in ultrafine particle thin film is studied, and the tra nsit time spread (TTS) and response time of peak value (t(M)) are disc ussed. The photoelectron's response time will increase with increasing energy of photons. If the surface potential barrier of thin film decl ines, the photoemissive sensitivity or quantum yield will rise, howeve r the response time will also increase, which means that response-time characteristic gets worse. As an example, the response time for Ag-O- Cs thin film is calculated for different cases when photoelectrons, ex cited in Ag ultrafine particles, travel through Cs2O semiconductor lay er to the surface and escape into vacuum. The calcutaed response time is about 50 fs if this thin film is irradiated by infrared rays of wav elength 1.06 mum.