No abstract available

[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 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] 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.

[en] The paper overviews experimental and theoretical studies of photogalvanic effects (PGEs) induced in graphene and carbon nanotubes (CNs) by polarized electromagnetic radiation. The following items are discussed: the helicity-dependent photon-drag and edge electric currents in graphene sheets, the circular PGEs in asymmetric graphene superlattices and chiral CNs, and pure valley currents generated in graphene by the interband absorption of linearly polarized light. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[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

No abstract available

[en] We report on the observation of the magnetic-field induced photocurrent in n-doped InSb/InAlSb quantum wells (QWs) excited by terahertz radiation. The photocurrent behavior upon variation of the radiation polarization, magnetic field strength, B, and temperature is studied. While at a moderate magnetic field the photocurrent exhibits a linear field dependence, at high magnetic fields it becomes nonlinear and even changes its sign. The experimental results are analyzed in terms of the magneto-gyrotropic photogalvanic effect (MPGE) based on the asymmetry of optical transitions and/or asymmetric relaxation of carriers in the momentum space. We demonstrate that the sign inversion of the photocurrent is caused by the interplay of two mechanisms: The spin mechanism, which yields a saturation of the current at high magnetic fields due to the large Zeeman splitting in InSb-based QWs, and the orbital mechanism, which depends linearly on B and has an opposite sign. The latter contribution dominates the total current at high magnetic fields.

[en] The stationary two-wave interaction in an optically uniaxial photorefractive crystal on a transmission photorefractive grating produced due to the photogalvanic or diffusion mechanism is considered. The possibility of the nonunidirectional amplification of a weak wave, which is consistent with a change in its polarisation state caused by the interaction, is shown. The conditions of the nonunidirectional energy exchange in Fe:LiNbO₃ and SBN crystals with the local and photorefractive responses, respectively, are determined. (nonlinear optical phenomena)