Conversion of radiation from high-power UV lasers in gases and vapors by stimulated Raman scattering

We have systematized experimental data on conversion of high-power UV radiation in gases and vapors by stimulated Raman scattering (SRS). We consider the features of nonlinear processes mediated by UV photons. We formulate the requirements for the pump beam parameters and describe specific laser systems satisfying these requirements. We analyze in detail ways to optimize the SRS conversion process in hydrogen and methane from the viewpoint of both overall efficiency and the efficiency of conversion to a specified SRS component. We present results obtained in SRS experiments in vapors of different metals. We discuss in detail the optimal conditions for conversion of UV radiation to the visible range in lead vapors. We show the effect of other nonlinear processes on the SRS process, and indicate conditions in which this effect is minimal. We describe some effects observed in the experiments. In conclusion, we present data on the wavelengths and conversion efficiencies for radiation from different lasers in different gases and vapors, and briefly describe possible applications of lasers with SRS cells. Institute of High-Current Electronics, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 90–116, March, 1998.     

Phase transitions in RbxK1−x LiSO4 mixed crystals

Structural phase transitions in Rb_xK_1−x LiSO₄ mixed crystals (with x varying from 0 to 1) have been studied from the melting point to liquid-nitrogen temperature. Calorimetric (DTA and DSM) data, birefringence and optical polarization measurements were used to construct the full phase (T-x) diagram. It has been established that crystals of most compositions (x⩽0.95) grow in the hexagonal-trigonal KLiSO₄ structure. Replacement of K by the larger Rb atom results in a considerable increase of the region of existence of the P31c phase and expulsion of the high-temperature hexagonal phase. Fiz. Tverd. Tela (St. Petersburg) 40, 1341–1344 (July 1998)     

Luminescence spectral properties of Sm-and (Ce, Sm)-containing silica gel glasses

The spectroscopic behavior of Sm³⁺ ions is investigated in monoactivated and coactivated (with cerium) glasses obtained by the direct sol-gel-glass transition. It is shown that the majority of the Sm³⁺ ions form optical centers of the same type, whose luminescence spectral characteristics depend weakly on the concentration of the activator and the technique used to introduce it. Complex centers, including Sm³⁺ and Ce⁴⁺ ions bound by bridge oxygen, are also formed in the coactivated glass during the pore nucleation stage. The Sm³⁺ ions in these centers are characterized on the average by higher local symmetry, the efficient enhancement of luminescence by photoreduced (Ce⁴⁺)⁻ ions, and its extinction by Ce-containing clusters. Fiz. Tverd. Tela (St. Petersburg) 40, 458–465 (March 1998)     

Regularities of triplet-triplet annihilation of aromatic hydrocarbons in aqueous micellar solutions of sodium dodecyl sulfate

Investigation of deactivation processes in triplet states of a series of aromatic hydrocarbon molecules (antracene, 1,2-benzantracene, and 3,4-benzpyrene) made it possible to reveal the presence of triplet-triplet annihilation of the molecules in aqueous micellar solutions of sodium dodecyl sulfate. It is shown that the effect of microheterogeneous solutions on the process of triplet-triplet annihilation manifests itself in an increase in the probability of excimerization upon dissociation of triplet pairs of 1,2-benzantracene and 3,4-benpyrene molecules compared to one-component solutions. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 5, pp. 626–628, September–October, 1997.     

Encoding voice fundamental frequency into vibrotactile frequency.

Measured in this study was the ability of eight hearing and five deaf subjects to identify the stress pattern in a short sentence from the variation in voice fundamental frequency (F0), when presented aurally (for hearing subjects) and when transformed into vibrotactile pulse frequency. Various transformations from F0 to pulse frequency were tested in an attempt to determine an optimum transformation, the amount of F0 information that could be transmitted, and what the limitations in the tactile channel might be. The results indicated that a one- or two-octave reduction of F0 vibrotactile frequency (transmitting every second or third glottal pulse) might result in a significant ability to discriminate the intonation patterns associated with moderate-to-strong patterns of sentence stress in English. However, accurate reception of the details of the intonation pattern may require a slower than normal pronounciation because of an apparent temporal indeterminacy of about 200 ms in the perception of variations in vibrotactile frequency. A performance deficit noted for the two prelingually, profoundly deaf subjects with marginally discriminable encodings offers some support for our previous hypothesis that there is a natural association between auditory pitch and perceived vibrotactile frequency.     

A measurement of single electrons,electron pairs,and associated phenomena,in proton-proton collisions at the CERN ISR

Measurements of single-electron production in proton-proton collisions at the CERN ISR are presented for five centre-of-mass energies √s = 23.5, 30.6, 44.8, 52.7, and 62.4 GeV. The invariant cross sections for single electrons with transverse momenta of 0.60 to 4.7 GeV/c are given. Measurements of electron-positron pairs and measurements of charged hadrons produced in association with the single electrons, are also reported.     

Influence of acoustic radiation on the sensors of a gyrostabilized platform

The paper analyzes the joint effect of acoustic radiation and angular motion of a launch vehicle on the gyroscopic sensors of a three-axis gyroplatform and the operation of the stabilizer under synchronous and asynchronous swinging.Translated from Prikladnaya Mekhanika, Vol. 40, No. 10, pp. 122–130, October 2004.     

Tunnelexperimente an amorphen Supraleitern

Zeitschrift für Physik A Hadrons and nuclei - Superconducting disordered and amorphous films of Bi, Ga, Al are studied by the tunneling technique. The values of the reduced energy gap...     

Ko and λ production at the CERN ISR

Transverse momentum distributions of $\text{λ}{}^{\mathrm{o}}\text{,}\text{λ}{}^{\mathrm{o}}$, and K^o, produced in pp collisions at x = 0, have obtained at the CERN ISR. The K^o yield is in agreement with published K⁺, K^? results, obtained at this centre-of-mass energy (√s≈44 GeV). The results on $\text{λ}{}^{\mathrm{o}}\text{and}\text{λ}{}^{\mathrm{o}}$ production obtained in this experiment are compared with results obtained at lower centre-of-mass energies.     

On a method of approximation of solutions to delay differential equations

Connections between solutions to a class of systems of ordinary differential equations of a large dimension and delay equations are studied. A new method is justified for approximation of solutions to delay equations.