Determination of the atomic-state densities of some energy levels in Ar−Br2 mixtures

The atomic-state densities of the 4s Ar energy levels and 5s Br energy levels in Ar-Br₂ mixtures have been determined as function of current strenght.     

Determination of the atomic-state population in A Kr-Br2 mixture

The atomic-state populations of the 5s[1$\text{1}\text{2}$]° metastable level of Kr and of the 5s²P_{$\text{3}\text{2}$} resonant level of Br in a Kr-Br₂ mixture have been determined as functions of current strength. Occurrence of energy transfer from the Kr-level to the Br-level has been verified.     

耗散系统中实现原子态量子隐形传态的保真度

本文运用全量子理论并结合数值计算方法,研究了压缩真空库中利用原子纠缠态作为量子通道实现原子态量子隐形传态的保真度,讨论了被传送的原子初态形式以及压缩库的压缩参数r对保真度的影响.研究表明:当只有输入态受噪声影响,则被传送的初始态中基态概率越大的态,保真度越高;而当量子通道受影响时,则基态和激发态概率相等的原子叠加态传送的保真度最大. 关键词： 量子隐形传态 压缩真空库 保真度     

Spin densities in some diazine and naphthyridine anions

The E.S.R. spectra of a number of diazine and naphthyridine anions are interpreted using molecular orbital theory. Results obtained with different theoretical procedures are compared and discussed.     

Spin densities in some odd alternant radicals including linear polyene radicals

An approximate unrestricted Hartree-Fock method is used to calculate spin densities in the odd alternant radicals cyclohexadienyl, benzyl, perinaphthenyl and triphenylmethyl and the linear polyene radicals from allyl to C₁₉H₂₁. The results agree quite well with the exact calculations and with empirical estimates as well as with experimental data on hyperfine splitting constants and E.S.R. second moments.     

Emission characteristics of a barrier discharge in an Ar-H2O mixture

We have experimentally studied the UV radiation of a low-temperature barrier discharge plasma in an Ar-H₂O mixture. The spectral interval 300–400 nm has been examined in detail. Addition of argon with a pressure of 24 kPa to a barrier discharge in water vapor at a pressure of ～0.1 kPa leads to a ninefold increase in the UV radiation power of excited hydroxyl molecules. An increase in the duration of the UV radiation pulse of the mixture in the longitudinal discharge decay has been achieved for the first time, which may be direct evidence of energy transfer from metastable argon atoms to water molecules. An estimate of the upper boundary of the dissociative excitation rate constant of hydroxyl molecules OH*(A ²Σ⁺) upon interaction of metastable argon atoms with water molecules has been obtained.     

Detonation in an aluminum-Teflon mixture

Detonation in an aluminum-fluoroplastic-4 (Teflon) mixture is studied experimentally. To increase reactivity, the initial mixture is pretreated in a mechanochemical activator. As a result, a mechanically activated composite is obtained in the form of thin aluminum layers in a Teflon matrix. The action of a shock wave on a composite sample initiates the steady detonation regime, in which the initial and final substances are in the condensed state. Depending on the percentage composition and density of the mixture, the detonation velocity varies from 700 to 1300 m/s for the speed of sound below 100 m/s in the initial composition. The steady detonation velocity changes insignificantly when sample pores are filled with helium instead of air. The results prove that it is possible in principle to reach the steady detonation regime in reactive condensed mixtures forming final reaction products in the solid state.     

Fourier analysis of spherically averaged momentum densities for some gaseous molecules

The spherically averaged autocorrelation function,B(r), of the position-space wavefunction, ψ($\text{r}$), is calculated by numerical Fourier transformation from spherically averaged momentum densities, ?(p), obtained from either theoretical wavefunctions or (e,2e) electron-impact ionization experiments. Inspection of B(r) for the π molecular orbitals of C₄ H₆ establishes that autocorrelation function differences, ΔB(r), can be qualitatively related to bond lengths and numbers of bonding interactions. Differences between B(r) functions obtained from different approximate wavefunctions for a given orbital can be qualitatively understood in terms of wavefunction difference,Δψ($\text{r}$), maps for these orbitals. Comparison of the B(r) function for the 1a_u orbital of C₄H₆ obtained from (e,2e) momentum densities with that obtained from an ab initio SCF MO wavefunction shows differences consistent with expected correlation effects. Thus, B(r) appears to be a useful quantity for relating spherically averaged momentum distributions to position-space wavefunction differences.     

Efficiency of an electron-beam-pumped chemical laser with an SF6-H2 working mixture

Results are presented from a study of HF lasers pumped by non-chain chemical reactions initiated by a radially convergent and by a planar electron beam. The main channels of formation of vibrationally excited HF molecules are analyzed. The distribution of the energy density of the radiation in the output beam of a wide-aperture laser is measured. In 30 liters of a mixture of SF₆:H₂=8:1 at a pressure of 1.1 atm an output energy of ∼200 J is obtained at an ∼11% efficiency with respect to the energy deposition. It is shown that the admixture of a buffer gas of neon or argon improves the uniformity of the radiation energy distribution in the output beam of an HF laser pumped by a non-chain chemical reaction and initiated by an electron beam, and it also increases the output energy. Zh. Tekh. Fiz. 69, 76–81 (January 1999)     

Initiation of a volume discharge in an elevated-pressure gaseous mixture of CO2 lasers

Initiation of a volume discharge in the gaseous mixture of CO₂ lasers at above-atmospheric pressures for a discharge gap 5 cm long is considered. It is shown that preionization by soft X rays allows initiation of the volume discharge when ratio E/p (p = 5 atm) is below a static breakdown value.     

Convective burning of an aluminum-water mixture

The burning of a stoichiometric mixture of aluminum (PAP-2 powder) with water in a constant-volume bomb is studied. It is shown that, depending on the charge diameter and igniter-generated pressure, three situations can arise: the mixture does not burn, burns slowly (in the layer-by-layer mode), or burns rapidly in the convective mode. The characteristics of the rapid burning, such as the effect of the igniter-generated burning, charge length, and initial charge density, are in general similar to those of the convective burning of mixtures of aluminum powder with an oxidizing agent (AP or PA), described in the literature. The difference lies in the fact that, due to a relatively low water activity as an oxidant, the convective burning of aluminum-water mixtures is harder to initiate, and it proceeds at a much lower velocity.     

The 4s electron densities of Fe impurity atoms in some transition and noble metals

From internal conversion experiments and the Mössbauer effect measurements, the 4s electron density and isomer shift for Fe impurity atoms in Cr, Ni, Cu, Pt and Au metals were studied. The M and N shell conversion electron spectra of the 14.4 keV transition of⁵⁷Fe were measured using a high resolution β-ray spectrometer and analyzed using a deconvolution methods. The Mössbauer effect measurements were performed by a standard spectrometer with a moving absorber. Most of the samples showed isomer shift values consistent with the published ones. It is concluded that the 4s electron density, \(\rho _{4_S} (0)\) , at the nucleus of⁵⁷Fe embedded is nearly equal in these host metals. The relation between \(\rho _{4_S} (0)\) and the isomer shift indicates that \(\rho _{3_S} (0)\) plays an important role in the variation of the isomer shift.     

Effect of an Xe additive on the degree of translational nonequilibrium of an He-O2-H2 mixture in a shock wave front

Computer simulations of the experimentally observed detonation threshold shift upon adding small amounts of Xe with the use of the direct simulation Monte Carlo method once again confirmed that this effect is associated with a substantial increase in the degree of translational nonequilibrium in the shock wave front. It was demonstrated that, when the presence of hydrogen in the mixture is taken into account, the calculated degree of translational nonequilibrium becomes higher. In addition, the effect of Xe was observed to grow stronger as the Xe concentration was decreased from 0.5 to 0.25%.     

Electron-pair densities of group 2 atoms in their and terms

Electron-pair intracule (relative motion) and extracule (center-of-mass motion) densities are studied in both position and momentum spaces for the ¹ P and ³ P terms of the group 2 atoms Be (atomic number Z =4), Mg (Z =12), Ca (Z =20), Sr (Z =38), Ba (Z =56), and Ra (Z =88). In position space, the ¹ P - ³ P difference in the intracule densities shows that the probability of a small interelectronic distance is larger in the triplet for all the six atoms, as reported for the lightest Be atom in the literature. The position-space extracule density clarifies that the triplet electrons are more likely to be at opposite positions with respect to the nucleus than the singlet electrons for all the atoms. In momentum space, the singlet generally has a larger probability of a small relative momentum between two electrons as a na?ve manifestation of the Fermi hole in the triplet. The extracule density in momentum space shows that the ¹ P term has a distribution larger in a large center-of-mass momentum region than the ³ P term. Received: 26 August 1998 / Received in final form: 1 February 1999