The generation and decay of photoelectrons is an important factor in improving photographic efficiency of silver halide
crystals. Microwave absorption phase-sensitive detection technology designed by our experiment group, was used to
non-contact measure the transmission characteristic of photoelectronic in [Fe(CN)6]4- uniformly-doped AgCl
microcrystals. The signal of free and shallow-trapped photoelectrons were measured in-phase. It is found that the
photoelectrons decay time in cubic AgCl microcrystals doped with [Fe(CN)6]4- is longer than that of undoped samples at
the first exposure time. And the photoelectrons decay time becomes longer with the doping concentration increasing. As
is shown the doping centres can act as shallow electron traps. The results also show the photoelectrons decay time
decreases significantly till becoming a constant after a few minutes exposure, and the constant is lower when the doping
concentration is higher. By analysis the photoproduct is silver clusters with the characteristic of deep electron traps in the
microcrystals. The measurement of photoelectrons by microwave absorption phase-sensitive detection technology can
give evidence for the improving performance of the photosensitive material, optical information storage material and so
There will be large numbers of carriers coming into being in the interior of silver chloride microcrystals when illumination acts on it. Microwave absorption and dielectric spectrum detection technology with high temporal resolution (1ns) can detect instantaneous decay process of photoelectrons. In this work, the photoelectron decay action of spectral sensitized silver chloride emulsion is measured by microwave absorption and dielectric spectrum detection technology. By analyzing the measured results, it is found that when plentiful dye adsorb on silver chloride microcrystals film, the photoelectron decay of silver chloride emulsion becomes faster than that of pure emulsion. However it is not that the more the dye is adsorbed, the faster the photoelectron decay will be. When the adsorbed dye reaches a certain level, the photoelectron decay becomes slower than the fastest instance. Combining with photoelectron decay kinetics theory it is found that the above results are induced by two kinds of effect from dye adsorption.
The characteristic of semi-conduct will be influenced, when environmental conditions act on it. Silver halide
microcrystals, kind of false compositive microcrystals, is a kind of typical photoelectric material. In this work, the silver
chloride microcrystals adsorbing dye are excited by laser with different wavelengths, the photoelectron signals of which
are measured by microwave adsorption dielectric spectrum equipment with a high time resolution (1ns). It is found that
the photoelectron decay time of pure emulsion excited by 355nm and 532nm laser is respective 109ns and 47ns; The
photoelectron decay time of sensitized emulsion with sensitization concentration of 4mg/40g is respective 83ns and 23ns
when it is excited by 355nm and 532nm laser; The photoelectron decay time of sensitized emulsion with sensitization
concentration of 8mg/40g is respective 76ns and 12ns when it is excited by 355nm and 532nm laser. The results show
that the change extent of photoelectron decay are not the same when silver chloride emulsion is excited by laser with
different wavelengths, so the sensitive effect of adsorbed dye is different under different exposal wavelengths.
Photoelectron decay characteristics in latent image formation process directly reflect photographic efficiency of silver halide crystals. Dopants can be substitutionally incorporated into AgX crystals and influence the photoelectron action by introducing appropriate electron traps. Long photoelectron lifetime can improve the photographic efficiency of intrinsic or unsensitized grains. In general, AgCl are intrinsic or unsensitized emulsion. Cubic AgCl microcrystals doped with K4Ru(CN)6 were measured by microwave absorption and dielectric-spectrum technique. Measurement of the photoelectron decay process as a function of doping position and concentration can provide important information about the electronic properties. The experimental results show the photoelectron decay time at room temperature is more or less longer than undoped samples. The photoelectron decay time increases with the doping concentration increasing and with the doping position closer to the core except for position 30%Ag and over high concentration 3.21x10-5 mol/molAg. When doping position is 30%Ag, the photoelectron decay time reaches its maximum at the doping concentration of 1.5x10-5 mol/molAg. At doping concentration 3.21x10-5 mol/molAg, the photoelectron decay time reaches its maximum at the doping position 60%Ag. Through studying the photoelectron decay behavior, we can know the doping can improve the image quality of AgCl emulsion.
Dopants can be substitutionally incorporated into AgX crystals and influence the photoelectron action and the latent image formation by introducing appropriate electron traps. The dopant [IrCl6]4- was introduced in either the core, the subsurface shell or the outer shell of cubic AgCl microcrystals and its concentration was varied from 2.60×10-7mol/molAg up to 2.61×10-5mol/molAg. The emulsion sample exposed to a YAG super short pulse laser (355nm, 35ps) were measured by microwave absorption and dielectric-spectrum technique. The experimental results show the photoelectron decay time at room temperature decreases with the doping concentration increasing for any given doping position especially as the doping near the core. Results also show the photoelectron decay time at room temperature increases when the doping position is closer to the surface especially for higher doping concentration at 2.61×10-5 mol/molAg. This can be explained that [IrCl6]4- can act as both shallow electron trap and deep electron trap with doping condition varying. When the doping level is lower and doping position is closer to the surface, the sensitivity of AgCl emulsion is higher. The knowledge obtained from this study may be useful for practical microcrystal design making use of dopants.