DISPROPORTIONATION AND THERMAL LENS EFFECTS PRODUCED BY AR-RADIATION ON SILVER-HALIDE SUSPENSIONS( LASER)

The thermal lens spectrometric (TLS) signal increases when Ag+ is adde d to a halide solution or vice versa. The change in the TLS signal is due to the disproportionation and darkening of the surface of the silv er halide particles produced by the Ar+ laser pump radiation. The chan ge in the TLS signal depends on the nature of the ions in excess. The injection of an excess Ag+ into chloride and bromide solutions gives t he fastest and largest responses, respectively. TLS monitoring of titr ations of chloride solutions with Ag+ is also possible. Absorbance is effectively discriminated from scattering in the slightly turbid silve r halide suspensions.