Optical study of radicals (OH,O, H,N) in a needle-plate bi-directional pulsed corona discharge

In this study, analysis of optical emission spectra are used for the detection of OH (A²Σ) radicals and O (3p⁵P), H_α (3P) and N (3p⁴P) active atoms produced by the high-voltage bi-directional pulsed corona discharge of N₂ and H₂O mixture gas in a needle-plate reactor at one atmosphere. The relative vibrational populations and the vibrational temperature of N₂ (C, v') are determined. The effects of pulse peak voltage, pulse repetition rate and the added O₂ flow rate on the relative populations of OH (A²Σ) radicals and O (3p⁵P), H_α (3P) and N (3p⁴P) active atoms are investigated. It is found that when pulse peak voltage and pulse repetition rate are increased, the relative populations of those excited states radicals rise correspondingly. The relative population of OH (A²Σ) radicals decreases with increasing the flow rate of oxygen. The relative populations of O (3p⁵P), H_α (3P) and N (3p⁴P) active atoms increase with the flow rate of oxygen at first and exhibit a maximum value at about 30 ml/min. When the flow rate of oxygen is increased further, the relative populations of those excited states active atoms decrease correspondingly. The main involved physicochemical processes also have been discussed.     

Recent Result of Muon Catalyzed t–t Fusion at RIKEN-RAL

We have measured X-rays and neutrons associated with the muon catalyzed t–t fusion process at the RIKEN-RAL Muon facility. In the X-ray measurement, we observed K_α and K_β X-rays originating from the muon sticking process in muon catalyzed t–t fusion, and obtained the K_α X-ray yield and the K_β/K_α intensity ratio. An average recoil energy of the (μ⁻α) atoms in a solid T₂ medium was determined from the observed Doppler broadening width of the K_α X-ray line. The obtained t–t fusion neutron has shown an exponential time spectrum with a single component and a continuous energy spectrum with a maximum energy of 9 MeV. We have determined the t–t fusion neutron yield, the t–t fusion cycling rate and the muon sticking probability from the neutron data. The obtained maximum neutron energy is a very peculiar value from the view point of the reaction Q value (11.33 MeV) with the three-particle decay mode at the exit channel: t + t → α + n + n + Q. The obtained neutron energy distribution was analyzed by a simple model with two neutron energy components; reasonable agreement has been obtained, suggesting a strong (n–α) correlation in the exit channel of the t–t muon catalyzed fusion reaction. This revised version was published online in August 2006 with corrections to the Cover Date.     

Wei Hua’s four-parameter potential: Comments and computation of molecular constants αe and εeXe

The value of adjustable parameterC in the four-parameter potentialU(r) =D _e [(1 - exp[-b(r -r _e)])/(1 -C exp[-b(r -r _e)])]² has been expressed in terms of molecular parameters and its significance has been brought out. The potential so constructed, withC derived from the molecular parameters, has been applied to ten electronic states in addition to the states studied by Wei Hua. Average mean deviation for these 25 states has been found to be 3.47 as compared to 6.93, 6.95 and 9.72 obtained from Levine, Varshni and Morse potentials, respectively. Also Dunham’s method has been used to express rotation-vibration interaction constant (α_e) and anharmonicity constant (ω_ex_e) in terms ofC and other molecular constants. These relations have been employed to determine these quantities for 37 electronic states. For α_e, the average mean deviation is 7.2% compared to 19.7% for Lippincott’s potential which is known to be the best to predict these values. Average mean deviation for (ω_ex_e) turns out to be 17.4% which is almost the same as found from Lippincott’s potential function.     

A Class of Well Behaved Charged Analogues of Schwarzchild’s Interior Solution

A class of well behaved charged analogues of Schwarzchild’s interior solution has been obtained using a particular electric intensity. The solutions of this class are utilized to depict a superdense star model with surface density 2×10¹⁴ g cm⁻³. The solution obtained is new and the pressure (p), density (c ² ρ), velocity of sound and (p/(c ² ρ)) are monotonically decreasing towards the pressure free interface. Moreover the adiabatic constant is found to be more than (4/3) which is necessary for stability under radial perturbation. Also the electric intensity increases monotonically towards the surface. The well behaved model has the maximum mass M=1.740793M _Θ , Radius 12.130308 km. The redshift at the center and on the surface is given by z ₀=0.384261 and z _a =0.292489. Out of the models of superdense star obtained couple of models represent Vela Pulsar for (i) α ²=1.03, b=0.33, , Radius=10.8566 km, M=1.18331M _Θ , I=0.642601×10⁴⁵, (ii) α ²=1.1, b=0.3, , Radius=11.197533 km, M=1.311438M _Θ , I=0.774508×10⁴⁵. All the solutions mentioned above are reducible to Schwarzchild interior solution in the absence of charge.     

2p3/2?13x?1?3x?13d?1 X-ray satellites spectra in the Lα1 region of 4d transition elements

The X-ray satellite spectra arising due to 2p _3/2 ⁻¹3x ⁻¹−3x ⁻¹3d ⁻¹ (x ≡ s, p, d) transition array, in elements with Z = 40 to 48, have been calculated, using available Hartree-Fock-Slater (HFS) data on 1s ⁻¹−2p ⁻¹ 3x ⁻ and 2p _3/2 ⁻¹−3x ⁻¹,3x ⁻¹ Auger transition energies. The relative intensities of all the possible transitions have been estimated by considering cross — sections for the Auger transitions simultaneous to a hole creation and then distributing statistically the total cross sections for initial two hole states 2p _3/2 ⁻¹−3x ⁻¹ amongst various allowed transitions from these initial states to 3x ⁻¹ 3d ⁻¹ final states by Coster-Kronig (CK) and shake off processes. In both these processes initial single hole creation is the prime phenomenon. Each transition has been assumed to give rise to a Gaussian line and the overall spectrum has been computed as the sum of these Gaussian curves. The calculated spectra have been compared with the measured satellite energies in Lα₁ spectra. Their intense peaks have been identified as the observed satellite lines. The peaks in the theoretical satellite spectra were identified as the experimentally reported satellites α₃, α₄ and α₅, which lie on the high-energy side of the Lα₁ dipole line.     

Kramers-Kronig analysis of the reflectance spectra of Pb-doped Bi-4334 type glass and the corresponding glass-ceramic superconductor

The room temperature reflectance spectra in UV-VIS-NIR region (energy range of 0.6 to 6.2 eV) for glassy, partially crystalline and its fully crystalline superconducting ceramic phases of Bi_3.9Pb_0.1Sr₃Ca₃Cu₄O _x have been studied by Kramers-Kronig (KK) analysis. A comparative study of the energy loss function [− Im (1/ε)] and the absorption coefficient [α(E)] has been done. Excitions in the superconducting phase hitherto evidenced by the authors are located in the polarizable layers of the superconducting cuprate and their implications for superconductivity have been pointed out. An estimate of the optical band gap energy (E _g) has also been made from the linear fit ofα ² vs.E curve for the superconducting phase. Jezierski’s method ofR-extrapolations in the higher energy has been used to show that both methods yield results that agree quantitatively and can be relied upon.     

Doppler spectroscopy of a beam in the channel of a H− ion source

It is shown that high-accuracy contact-free measurements of the divergence and emittance of an accelerated H⁻ ion beam at the exit from the source can in principle be performed by passive Doppler spectroscopy of a beam of excited hydrogen atoms produced by neutralization of the ions with excitation on the residual gas in the source channel. The intensity of the H_α-line radiation detected by the Doppler system is calculated, taking into account the principal processes leading to the excitation and deexcitation of the 3s, 3p, and 3d levels of the hydrogen atoms in the beam, for residual gas densities of the order of 10⁻⁴–10⁻⁵ Torr in the source channel. The computed H_α-line intensity was confirmed experimentally, making it possible to perform photoelectronic detection of the spectral contour of the line in the current mode rather than the photon-counting mode. Zh. Tekh. Fiz. 68, 15–18 (June 1998)     

Single α-particle orbits and Bose-Einstein condensation in <Superscript>12</Superscript>C

Bosonic properties of α particles such as single-α orbits and occupation numbers in J^π = 0⁺, 2⁺, 1^- and 3^- states of ¹²C around the 3α threshold are investigated with the semi-microscopic 3α cluster model. As in other studies, we found that the 0⁺₂ (2⁺₂) state has dilute-3α-condensate-like structure in which the α particle is occupied in the single S (D) orbit with about 70% (80%) probability. The radial behaviors of the single-α orbits as well as the occupation numbers are discussed in detail in comparison with those for the 0⁺₁ and 2⁺₁ states together with the 1^-₁ and 3^-₁ states.     

Chemical, morphological and chromatic behavior of mural paintings under Er:YAG laser irradiation

Several pigments (malachite CuCO₃⋅Cu(OH)₂, azurite 2CuCO₃⋅Cu(OH)₂, yellow ochre (goethite α-FeOOH, gypsum CaSO₄⋅2H₂O), St. John’s white CaCO₃ formed from slaked lime) and respective mural paintings specimens were subjected to the free-running Er:YAG laser radiation in order to study their damage thresholds, in a broad range of laser fluences, both in dry and wet conditions. The specimens’ damage thresholds were evaluated by spectroscopic methods, colorimetric measurements and microscopic observation. The pigments containing –OH groups were found to be more sensitive than St. John’s white; hence the most sensitive paint layers in dry conditions are those containing malachite, azurite (both 1.3 J/cm²) and yellow ochre (2.5 J/cm²) as compared to the ones containing St. John’s white (15.2 J/cm²). The presence of wetting agents (w.a.) attenuated the pigments chemical alteration. The damage thresholds of all the paint layers, in presence of w.a., were found to be around 2.5 J/cm². The alteration was caused by thermo-mechanical damage and by binding medium ablation of a fresco and a secco prepared specimens, respectively.     

The electric field gradient of111Cd in an α-Al2O3 single crystal

Radioactive¹¹¹In⁺ ions were implanted into an α-Al₂O₃ single crystal. The hyperfine parameters of¹¹¹Cd at substitutional Al lattice sites were identified by measuring the perturbed angular correlation for different sample orientations. The electric field gradientV _zz =1.04(17)·10²²V/m² was obtained from the quadrupole coupling constant. This result is compared with the efg values of²⁷Al in α-alumina and¹¹¹Cd in α-Fe₂O₃, which also has the corundum structure. Two additional fractions with broad frequency distributions were observed, one of which is attributed to¹¹¹Cd atoms in a strongly distorted Al₂O₃-lattice.     

Time Variable Λ and the Accelerating Universe

We perform a deductive study of accelerating Universe and focus on the importance of variable time-dependent Λ in the Einstein’s field equations under the phenomenological assumption, Λ=αH ² for the full physical range of α. The relevance of variable Λ with regard to various key issues like dark matter, dark energy, geometry of the field, age of the Universe, deceleration parameter and barotropic equation of state has been trivially addressed. The deceleration parameter and the barotropic equation of state parameter obey a straight line relationship for a flat Universe described by Friedmann and Raychaudhuri equations. Both the parameters are found identical for α=1.     

Effect of vacuum magnetic field on the gravitodynamic stability of liquid jet

Summary  The MHD stability of a liquid jet (radiusR ₀ and density ϱ) under the influence of self-gravitating force has traditionally been studied using a normal-mode type of analysis. The dispersion relation is obtained and studied analytically and numerically. The axial magnetic fields inside and outside the jet have always stabilizing effects. The transverse magnetic field has a destabilizing effect. It is found that the largest doman of instability is fastly shrinking (as α> ?) with increasingH ₀ /H _G values,H _G 4(4πGϱ² R ² ₀ μ)^1/2, whereG is the gravitational constant. Some reported works are recovered as limiting cases from the present work.     

Optical radiation and ionization of hydrogen atoms in heterogeneous exothermal reactions proceeding in an electric field

Optical radiation related to the Balmer series (H_α, H_β, H_γ) of hydrogen atoms is discovered when studying the isothermal reaction of trimeric acetone peroxide decomposition on the surface of oxidized tungsten in a static electric field with a strength of up to 4 × 10⁶ V/cm at T = 300 K. The distance from the surface over which desorbing excited hydrogen atoms radiate is determined from the Stark splitting of the lines. Electronically excited atoms remaining on the surface ionize according to the surface ionization mechanism.     

The 2<Superscript>1/3</Superscript> rule for magnetic susceptibility of gadolinium

The dependences of the magnetization M and the magnetic susceptibility χ = ∂M/∂H of pure gadolinium (the concentration of foreign impurities is lower than 0.1 wt %) on the temperature T and the magnetic field H have been measured using a Quantum Design MPMS-5XL SQUID magnetometer. In this material, inhomogeneities of the atomic structure should not lead to a nonuniform distribution of the magnetic characteristics (including the Curie temperature T _C) over the volume of the sample. The obtained dependences of M and χ have been used to investigate the possibility of suppressing magnetic inhomogeneities of other types by magnetic fields with a strength of up to 50 kOe. It has been assumed that these inhomogeneities are suppressed when the specific relationship, namely, the 2^1/3 rule is fulfilled. The rule relates the portions of the dependence χ(T, H) which at the temperature T = T _C and at the maximum in the curve χ(T) (T = T _m ) depend on H in accordance with the H ^2/3 law. It has been shown that the portions separated from the experimental curves χ(T _C, H) and χ(T _m , H) obey the 2^1/3 rule.     

Toward direct determination of conformations of protein building units from multidimensional NMR experiments III

Chemical shielding anisotropy tensors have been determined, within the GIAO-RHF formalism using a smaller [6-31+G(d)] and two medium-size basis sets [6-311++G(d,p) and TZ2P], for all elements of the conformational library (altogether 27 structures) of the hydrophobic model peptide For-L-Phe-NH₂. The individual chemical shifts and their conformational averages have been compared to their experimental counterparts taken from the BioMagnetic Resonance Bank (BMRB). At the highest level of theory applied, for all nuclei but the amide proton, deviations between statistically averaged theoretical and experimental chemical shifts are as low as a few percent. One-dimensional (1D) chemical shift - structure plots do not allow unambiguous identification of backbone conformations. On the other hand, on chemical shift - chemical shift plots of selected nuclei, e.g., ¹H ^N with ¹⁵N or ¹⁵N with ¹³C ^α , regions corresponding to major conformational motifs have been found, providing basis for the identification of peptide conformers solely from NMR shift data. The 2D ¹H ^α -¹³C ^α as well as the 3D ¹H ^α -¹³C ^α -¹³C ^β chemical shift - chemical shift plots appear to be of special importance for direct determination of conformations of protein building units from multidimensional NMR experiments. 48 pairs of ¹H ^α -¹³C ^α data for phenylalanine residues have been extracted from 18 selected proteins and compared to relevant ab initio results, supporting the calculated results. Thus, the appealing idea of establishing backbone folding information of peptides and proteins from chemical shift information alone, obtained from selected multiple-pulse NMR experiments (e.g., 2D-HSQC, 2D-HMQC, and 3D-HNCA), has received further support.     

DFT molecular structure and initial assignment for the FTIR spectrum of ν7 band of nitromethane-D3

The preliminary analysis of the DFT calculations and the high-resolution Fourier transform spectrum of the ν₇ band of CD₃NO₂ have been carried out for the first time. The rotational structure up to J = 10 have been fitted using Watson’s A-reduction in I ^r representation with a standard deviation of 0.0048cm⁻¹. The rotational constants A, B, C have been obtained for the ν₇ state of CD₃NO₂ with good statistical significance.     

Non-analytical angular dependence of the upper critical magnetic field in a quasi-one-dimensional superconductor

We have derived the so-called gap equation, which determines the upper critical magnetic field, perpendicular to conducting chains of a quasi-one-dimensional superconductor. By analyzing this equation at low temperatures, we have found that the calculated angular dependence of the upper critical magnetic field is qualitatively different than that in the so-called effective mass model. In particular, our theory predicts a non-analytical angular dependence of the upper critical magnetic field, H _c2(0) − H _c2(α) ∼ α^3/2, when magnetic field is close to some special crystallographic axis and makes an angle α with it. We discuss possible experiments on the superconductor (DMET)₂I₃ to discover this non-analytical dependence.     

Cross sections and other parameters ofe − − H2O scattering (E i⩾50 eV)

Our previous theoretical work one ⁻ − H₂O scattering has been modified and extended to intermediate and high energiesE _i. Using the Bethe plot, we compare the present inelastic cross-sections with the experimental ionization cross sections. Total cross-sections are analytically represented asQ _TOT(cm²)=a.(E _ieV) ^−b and the parameters ‘a’ and ‘b’ are discussed for molecules H₂O, NH₃ and CH₄ in the rangeE _i=100–1000eV.     

Diffusion Coefficient of a Brownian Particle with a Friction Function Given by a Power Law

Nonequilibrium biological systems like moving cells or bacteria have been phenomenologically described by Langevin equations of Brownian motion in which the friction function depends on the particle’s velocity in a nonlinear way. An important subclass of such friction functions is given by power laws, i.e., instead of the Stokes friction constant γ ₀ one includes a function γ(v)∼v ^2α . Here I show using a recent analytical result as well as a dimension analysis that the diffusion coefficient is proportional to a simple power of the noise intensity D like D ^{(1−α)/(1+α)} (independent of spatial dimension). In particular the diffusion coefficient does not depend on the noise intensity at all, if α=1, i.e., for a cubic friction F _fric=−γ(v)v∼v ³. The exact prefactor is given in the one-dimensional case and a fit formula is proposed for the multi-dimensional problem. All results are confirmed by stochastic simulations of the system for α=1, 2, and 3 and spatial dimension d=1, 2, and 3. Conclusions are drawn about the strong noise behavior of certain models of self-propelled motion in biology.     

Spectrum of Non-Hermitian Heavy Tailed Random Matrices

Let (X _jk ) _j,k ≥ 1 be i.i.d. complex random variables such that |X _jk | is in the domain of attraction of an α-stable law, with 0 < α < 2. Our main result is a heavy tailed counterpart of Girko’s circular law. Namely, under some additional smoothness assumptions on the law of X _jk , we prove that there exist a deterministic sequence a _n ~ n ^1/α and a probability measure μ _α on \mathbbC{\mathbb{C}} depending only on α such that with probability one, the empirical distribution of the eigenvalues of the rescaled matrix (a_n^-1X_jk)_{1 ￡ j,k ￡ n}{(a_n^{-1}X_{jk})_{1\leq j,k\leq n}} converges weakly to μ _α as n → ∞. Our approach combines Aldous & Steele’s objective method with Girko’s Hermitization using logarithmic potentials. The underlying limiting object is defined on a bipartized version of Aldous’ Poisson Weighted Infinite Tree. Recursive relations on the tree provide some properties of μ _α . In contrast with the Hermitian case, we find that μ _α is not heavy tailed.