The physical chemistry of the silver photography processes, exposure, development and fixing, is briefly summarized. The mechanism of the autocatalytic development by the developer of the clusters produced in silver bromide crystals during the exposure which is controlled by the critical nuclearity of these clusters was understood from pulse radiolysis studies. The effective quantum yield Feff ...

In order to overcome the low utilization ratio of solar light and high electron-hole pair recombination rate of TiO2, the triangular Ag nanoparticle island is covered on the surface of the TiO2 thin film. Enhancement of the photocatalytic activity of the Ag/TiO2 nanocomposite system is observed. The increase of electron-hole pair generation is caused by the enhanced near-field amplitudes of loc...

Recent experimental investigations on the reduction of internal quantum efficiency with increasing current density in (AlInGa)N quantum well structures show that Auger recombination is a significant contributor to the so-called "droop" phenomenon. Using photoluminescence (PL) test structures, we find Auger processes are responsible for at least 15 % of the measured efficiency droop. Furthermore...

The optimization of interfacial charge transfer is crucial to the design of dye-sensitized solar cells. In this paper we address the dynamics of the charge separation and recombination in liquid-electrolyte and solid-state cells employing a series of amphiphilic ruthenium dyes with varying hydrocarbon chain lengths, acting as an insulating barrier for electron-hole recombination. Dynamics of el...

We employ transient absorption spectroscopy to record the absorption spectrum of photogenerated charge carriers in Cu2O. We have found that CO2 reduction in Cu2O is limited by fast electron-hole recombination. The deposition of RuOx nanoparticles on Cu2O results in a twofold increased yield of long-lived electrons, indicating partially reduced electron-hole recombination losses. This observatio...

A theory for the spontaneous emission due to radiative recombination of excitons in amorphous semiconductors is presented. Four possibilities are considered: (i) both the excited electron and hole are in their extended states, (ii) the electron is in the extended and the hole in tail states, (iii) the electron is in tail and the hole in extended states and (iv) both are in their tail states. It...

We have studied the influence of structural defects on the spatial variation of radiative and nonradiative recombination in an InGaAs/AlGaAs/GaAs resonant cavity enhanced npn heterojunction phototransistor ~HPT! structure using cathodoluminescence ~CL! and electron beam-induced current ~EBIC! imaging. Absorber layers of InGaAs/GaAs multiple quantum wells ~MQWs! are used to provide the photosens...

We show that the order of energies of negative (X ) and positive (Xþ) trions in quantum wires is determined by the relative electron and hole lateral confinements. For equal electron and hole confinement, Xþ has a larger binding energy, but a small imbalance towards a stronger hole localization changes the order of the X and Xþ recombination lines in the photoluminescence spectrum.

In a previous paper we studied an injected electron-hole pair in crystalline polyethylene (PE) and found that the exciton becomes weakly self-trapped in a narrow interchain pocket comprised between two gauche defects. Despite the large energy stored in the trapped excitation, there did not appear to be a direct nonradiative channel for electron-hole recombination. Actual polyethylene systems of...

The mechanism and dynamics of charge separation and charge recombination in synthetic DNA hairpins possessing a stilbenedicarboxamide linker and a single guanine-cytosine base pair have been reinvestigated. The combination of femtosecond broad-band pump probe spectroscopy, nanosecond transient absorption experiments, and picosecond fluorescence decay measurements permits analysis of the formati...