Chemical sensitization of tabular-grain emulsions in the presence of sensitizing dye

This thesis considers the role a spectral sensitizing dye plays in chemical sensitization for tabular-grain emulsions. Different approaches for introducing sensitizing dye have been chosen in conjunction with sulfur-thiocyanate-gold (S-SCNAu) chemical sensitization, 1. At the completion of nucleation (NUC) 2. At various precipitation completion points (pcp) a. At 35% pcp b. At 70% pcp c. At 80% pcp d. At 90% pcp e. At 100% pcp (i.e., at the beginning of Ostwald ripening) 3. Before chemical sensitization with varied digest addition sequences: Dye-SSCN- Au, Dye-SCN-S-Au 4. Conventionally: S-SCN-Au-Dye, i.e., dye introduced after chemical sensitization (control). It also considers what happens for dye addition at various pcp to grain morphologies via electron microscopy study, to grain size distribution via turbidity measurement, to dye absorption via spectrogram investigation, and to the efficiency of chemical sensitization. Pure silver bromide emulsions were prepared with a linear ramp flow program through a computerized system with pAg control. The conditions for digest giving the best sensitometric performance were determined

Visible submicron microdisk lasers

The authors describe the performance of submicron microdisk lasers fabricated within InGaP/InGaAlP quantum well material working at room temperature. The smallest lasers, with diameters of approximately 600 nm, feature ultrasmall mode volumes and exhibit single mode operation at low threshold powers. Their small cavity volumes of approximately 0.03 µm^3 enable microdisk lasers to be used as spectroscopic sources. Here the authors demonstrate the fabrication and characterization of visible, monolithically fabricated, submicron microdisk lasers