Abstract: The temperature dependence of sensitivity of a finegrain silver iodobromide emulsion sensitized by different sensitizers was determined in a temperature range between 25 to 100℃ at an exposure time of one millisecond. In a result, the sensitivity increases with increasing temperature for all the samples except which was sulfursensitized. For a sulfursensitized emulsion, the sensitivitiy first increases as temperature increasing, and then decreases when temperature is over 50℃. Some factors were discussed as the reason for causing the thermal sensitization effect. In conclution, it is considered that the thermal sensitization effect plays an important part in the infrared presensitization phenomenon that was first observed by G. F. Frazier.

Key words: thermal sensitization, infrared presensitization, photographic chemistry