No abstract available

[en] The investigation of laser influence (0.63 μm) and gamma-radiation on short-circuit current in CuGaSe₂. The observable inversion of short-circuit current dependent on wave length and also the current intensity change and widening to long-wave side is connected with carrier concentration increase after treatment by laser and gamma-radiation

[en] Optogalvanic (OG) interaction is simulated and studied in a segmented hollow-cathode discharge (SHCD). HCD-lamps are used to induce an OG signal by their own emission or by that of another lamp. The efficiency of the OG of a Ne/Cu HCD lamp in the range 320-380 nm is estimated theoretically. An irregular galvanic peak arising near the inflection point in the i-V curve (∂V/∂i<0) is detected. Its origin is related to Penning ionization of the sputtered cathode material. (paper)

[en] The photogalvanic cells are rechargeable device with the sun light in which surfactant solutions are potentially important for efficient energy conversion and storage. Here, effect of cationic cetyltrimethyl ammonium bromide (CTAB), anionic sodium dodecyl sulphate (SDS) and non ionic tween 80 surfactants on the electrical output of the cationic oxazine dye brilliant cresyl blue (BCB)-fructose (redox couple) system in photogalvanic cells have been studied. For this, the photopotential and photocurrent for different cells having BCB-fructose system without and with surfactant (CTAB, SDS and tween 80) in the alkaline medium have been measured. The total 30 different cells have been prepared for optimizing the concentration of electrolytes corresponding to the higher electrical out put. Generally, the electrical output increases in presence of a particular surfactant, due to increase in solubilization and stabilization properties of dye molecules in the water. The amount of enhancement in electrical output of BCB-fructose system was highest with SDS and lowest with tween 80, i.e. the order for BCB-fructose system with different surfactants in photogalvanic cells is: BCB-fructose-SDS > BCB-fructose-CTAB > BCB-fructose-tween 80. This order for electrical output was good agreement with the stability order of BCB-SDS/CTAB/tween 80 system, on the basis of spectrophotometric study. Hence, among these surfactants, SDS has stronger capacity, (due to opposite charge on BCB and SDS) to stabilize the BCB-fructose system leads to enhancement in electrical output of photogalvanic cells. Therefore, dye and surfactant, having chemical structure, like BCB and SDS, has a great importance of improvement of electrical performance to photogalvanic cells in the future.

[en] We present new experimental data on the energies and quantum defects of the highly excited states in mercury using the laser optogalvanic detection technique in conjunction with a RF discharge cell. The 6snp ³P₂ (12 ≤ n ≤ 25) and 6snf ³F₄ (9 ≤ n ≤ 52) Rydberg series have been observed via two photon excitation from the 6s6p ³P₂ intermediate state, which is collisionally populated in the RF discharge. Three lines corresponding to transitions from the 6s6p ³P₀ metastable state to 6s8p ³P_0,2 and 6s5f ³F₂ states are also located. The 6snf ³F₄ Rydberg series to such high n-values are reported for the first time

[en] Photo-galvanic effects were studied in a photo-galvanic cell containing oxalic acid as reductant and Brilliant Cresyl as photosensitizers. The photo potential and photo current generated were 320.0 mV and 80.0 uA, respectively. The effects of different parameters on the electrical output of the cell were observed and a mechanism has also been proposed for the generation of a photocurrent in a photo-galvanic cell. (author)

No abstract available

[en] The measurement precision and accuracy were evaluated for anisotopic analysis of uranium using diode laser-excited optogalvanic spectroscopy. The ratio of ²³⁵U/(²³⁵U +²³⁸U) was measured using the 776 nm uranium isotope line for five samples ranging from depleted to enriched ²³⁵U composition. The percent relative error (accuracy) with respect to thermal ionization measurements ranged from 2.38% for a nominally 20% enriched ²³⁵U sample to slightly greater than 30% error for a depleted one. The sample-to-sample precision, determined using three different cathodes, was found to be ±3.5% RSD. The ratios showed no trends or biases, varying about a mean of 0.21 and ranging from a high of nearly 0.23 to a low of 0.18. A search was conducted for a stronger atomic line and a matching higher power diode laser in an attempt to improve the signal-to-noise ratio for the depleted case. Using a 150 mW diode laser that produced nominally 42 mW chopped power at 831.84 nm, a depleted uranium oxide sample was found to contain 0.26% ²³⁵U, within 3.7% of the value found using thermal ionization mass analysis. Using this same laser, the run-to-run reproducibility improved to ±7.8% from ±13.6%. This level of accuracy and precision is sufficient for screening applications, where preliminary information about the isotopic composition of a sample provides the incentive for additional analysis using more precise techniques. 20 refs., 5 figs., 3 tabs

[en] Highlights: • A new vertical configuration is proposed for photogalvanic cells. • The proposed vertical photogalvanic cell is mathematically modeled. • A numerical model is built for more detailed analysis. • Device parameters for high power conversion efficiency are determined. • Efficiencies of 13% can be expected from the vertical photogalvanic cell. - Abstract: Photogalvanic solar cells, the original dye based solar cell, have yet to fulfill their promise as a low fabrication cost, scalable energy conversion system. The efficient performance of photogalvanic cells relies on high dye solubility and selective electrodes with fast electron transfer kinetics. A new configuration is proposed for photogalvanic cells that removes these impractical requirements. Instead of illuminating the device through the electrode, as is the conventional approach, a new vertical configuration is employed with light coming between the two electrodes. This way, the light absorption and hence electron generation is spread through the depth of the device. The depth therefore can be adjusted according to the concentration of the dyes to absorb all the incoming photons even with low solubility dyes. As a result of distributed electron generation, unreasonably fast electrode kinetics are no longer required. The proposed configuration is mathematically modeled and the advantages over the conventional cell are shown. A numerical model is built for more detailed analysis that gives practical guidelines for working towards device parameters with high power conversion efficiency. The readily available Thionine-Iron dye-mediator couple could achieve 6% efficiency if highly selective electrodes are used, compared to 0.45% at best using the conventional approach. The analysis suggests that upon the realization of highly selective electrodes and an improved dye/mediator couple, an efficiency of 13%, and potentially higher, should be achievable from the new configuration

[en] We report on the observation of a modulation on the circular photogalvanic effect (CPGE) imposed by an extra optical radiation in a GaAs-based two dimensional electron gas system. The wavelength of the radiation for exciting the CPGE is 1064 nm and the wavelength of the modulation is 532 nm. The experiment is carried out from 77 K up to room temperature. The 1064 nm induced CPGE modulated by the 532 nm radiation increases as the increasing temperature. We also vary the power of the modulation beam to investigate the intensity dependence of the modulation effect. The modulation exhibits a linear dependence at low intensity. As the intensity increasing, we observe a saturation at certain level of the intensity and a suppression of the modulation when the intensity is further increased. The investigation of photoconductivity reveals that the change of the photoexcited charge carrier density has little contribution to the radiation modulation effect. Therefore, the microscopic mechanism of the radiation modulation effect can be attributed to the modulation of spin-orbit interaction in the structure.