Determination of some atomic-state densities in an Xe-Br2 mixture

The atomic-state densities of the 6s[1 $\text{1}\text{2}$]⁰ metastable Xe energy level and of the 5s⁴P_{$\text{1}\text{2}$}, 5s⁴P_{$\text{3}\text{2}$} and 5s⁴P_{$\text{5}\text{2}$}Br energy levels in an Xe-Br₂ mixture have been determined as a function of current strength.     

Excitation of bromine by means of krypton in Kr-Br2 mixtures

The atomic-state populations of the 5s⁴P_{$\text{3}\text{2}$} and 5s⁴P_{$\text{1}\text{2}$} resonant levels of Br in a Kr-Br₂ mixture have been determined as functions of current strength. An increase in flux of Br emission lines passing into 5s levels has been observed.     

Experimental transition probabilities of some Xe(I) lines

Using the light absorption technique in a ¹³²Xe afterglow plasma, we have measured the relative transition probabilities for several xenon lines which have the metastable 6s[$\text{3}\text{2}$]₂ or the resonant 6s[$\text{3}\text{2}$]₁ states as their lowest transition level. Because the transition probabilities of the 8819 Å (6p[$\text{5}\text{2}$]₃ ? 6s[$\text{3}\text{2}$]²) and 8280 Å (6p[$\text{1}\text{2}$]₀ ? 6s[$\text{3}\text{2}$]₁) lines are relatively well known, we have chosen these as reference lines and have thus been able to determine the absolute values of the transition probabilities for 19 xenon lines corresponding to transitions from 6p, 6p′, 7p, 8p, 9p, 4f and 5f to 6s[$\text{3}\text{2}$]₂, and for four lines corresponding to the transitions 6p?6s[$\text{3}\text{2}$]₁.     

Decays of 185m + gHg: Low-spin levels of 185Au as a test of nuclear models

The decay of ^{185m + g}Hg has been studied on-line with mass-separated sources from the ISOCELE facility. Precise conversion-electron measurements were performed with a 180° spectrograph. The $\text{13}\text{2}{}^{\mathrm{+}}$ isomeric state of ¹⁸⁵Hg ($\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 28 ± 5 s}$) was located with respect to the $\text{1}\text{2}$^? ground state ($\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 55 ± 10 s}$). A level scheme of ¹⁸⁵Au has been established. Two abnormally converted M1 transitions de-excite a state local at 330.2 keV. Excited states of ¹⁸⁵Au have been discussed in the framework of a “quasi-particle + axial rotor” approach, quasi-particle states being issued from Hartree-Fock plus BCS calculations using the SIII Skyrme force. Most of the low-spin negative-parity levels have been identified as h_{$\text{9}\text{2}$} + f _{$\text{5}\text{2}$} or p_{$\text{3}\text{2}$} + f_{$\text{7}\text{2}$} mixed states. The h_{$\text{11}\text{2}$} system has also been discussed using a model of asingle-j quasi-particle coupled to a triaxial rotor.     

A frequency-doubled frequency-stabilized cw ring dye laser for spectroscopy: A study of the λ = 293.3 nm transition in In1

In this letter a frequency-doubled frequency-stabilized CW ring dye laser for the wavelength region 292–305 nm is described. 500 μW U.V. power combined with a 2 MHz linewidth and a 7 GHz scanwidth has been obtained by intracavity frequency doubling in an ADA crystal. The set-up has been tested on the hyperfinestructure of the λ = 293.3 nm transition 5p²P_{$\text{3}\text{2}$} → 7s²S_{$\text{1}\text{2}$} in In1.     

Large angle production of stable particles heavier than the proton and a search for quarks at the CERN intersecting storage rings

Measurements have been performed on production of particles with mass 1.5 GeV/c² and charge $\text{?}\text{2}\text{3}$ for θ_lab = 62.5° and $\text{s}\text{= 53}\text{GeV}$. At p_T = 0.7 GeV/c the relative rate of production of antideuterons to π^? is (5 ± 1) × 10^?5. The deuteron to antideuteron ratio is 3.7 ± 1.2. No new stable particle has been amongst 0.7 × 10⁸ charged particles entering our detector.     

A monte-carlo/molecular dynamics study of the diffusional recombination kinetics of C(a) + O(a) → CO(g) on Pt(111)

The diffusion constants for C and O adsorbates on Pt(111) surfaces have been calculated with Monte-Carlo/Molecular Dynamics techniques. The diffusion constants are determined to be D_C(T)=(3.4 × 10^?3e^{$\text{?13156}\text{T}$})cm²s^?1 for carbon and D_O(T) = (1.5×10^?3 e^{$\text{?9089}\text{T}$}) cm² s^?1 for oxygen. Using a recently developed diffusion model for surface recombination kinetics an approximate upper bound to the recombination rate constant of C and O on Pt(111) to produce CO_(g) is found to be (9.4×10^?3 e^{$\text{?9089}\text{T}$}) cm² s^?1.     

Alpha decay of neutron-deficient isotopes of tungsten

Three neutron-deficient isotopes of tungsten have been produced by the reactions of ²⁴Mg on targets of ¹⁴⁷Sm and ¹⁴⁴Sm. They are ¹⁶⁴W, E_α = 5.153 MeV, $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 6.3 s}$; ¹⁶³W, E_α = 5.385 MeV, $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 2.5}\text{s}$; and ¹⁶²W, E_α = 5.53 MeV, $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{< 0.25}\text{s}$.     

Spin and lifetime of the ω− hyperon

A total of 101 ω^? decays have been found in K^?p interactions at 10 and $\text{16 GeV}\text{c}$. The decay angular distribution has been fitted under the assumptions that the ω^? has spin either $\text{1}\text{2}\text{or}\text{3}\text{2}$. It has been found that the probability of isotropy (spin$\text{1}\text{2}\text{)}$ is less than one in a thousand, whereas the probability for spin $\text{3}\text{2}$ is about 70%. Thus, we exclude the spin $\text{1}\text{2}$ assignment. The lifetime of the ω^? is found to be (1.41_?0.24^+0.15) × 10^?10s, in agreement with our earlier result based on about $\text{1}\text{5}$ of the present sample.     

The cosmic microwave background and the hadron era of the early universe: A possible connection

A cosmological model is constructed which is a Friedman model, but with a finite ultimate temperature (T_F). A plausible argument is presented which suggests that the existence of T_F and the cosmic microwave background restricts the form of the hadronic level density:

, where A, B = constants. In our model, $\text{B =}\text{7}\text{2}\text{?}\text{3}\text{s}\text{,}\text{where}\text{s =}\text{positive}$ integer. The case $\text{s = 3 (B =}\text{5}\text{2}\text{)}$ is the well-known Hagedorn model; the Frautschi model corresponds to s = 6 (B = 3); the cases $\text{s = 1 (B =}\text{1}\text{2}\text{)}$ and s = 2 (B = 2) have not been considered before now. For each value of $\text{B <}\text{7}\text{2}$, the model gives the temperature (T_γ0) of the microwave background as a function of A, T_F and ?₀ (the present energy density of the universe). Two fascinating results then emerge: first, all estimates of T_γ0 favor a low density Friedman universe (?0 = 10^?31g/cm³), which rules out a universe with positive curvature; second, for ?₀ = 10^?31gr/cm³ the best estimate of T_γ0 (?3K) occurs for the Hagedorn model.     

Heat of mixing in HfCxN1−x compounds from XPS core level binding energy shifts

The XPS core level binding energies for the Hf4f_{$\text{7}\text{2}$}, Cls and Nls level in several nearly stoichiometric HfC_xN_1?x compounds are reported. Using the thermochemical model to calculate core level binding energy shifts in metals the heat of mixing as function of the HfC/HfN ratio is calculated from the position of the Cls binding energies. In addition it is shown that the Hf4f_{$\text{7}\text{2}$} and Nls binding energies can be used to obtain further thermochemical data for these compounds.     

On the cyclotron resonance width of an electron impurity system in two dimensions

Using the proper connected diagram expansion which incorporates the quasi-particle effect naturally we calculated the cyclotron resonance width γ in the extreme quantum limit.(a) γ ∝n

$\text{1}\text{2}$

_s B

$\text{1}\text{2}$

for a short range interaction, and (b) γ = π

$\text{1}\text{2}$

ze² κ^-1 <?crossed h.c.h;^-1 n

$\text{1}\text{2}$

_s for Coulomb interaction, are obtained. The field (B) and concentration (n_s)-dependence is in satisfactory agreement with experimental data. The variation γ = (γ²₁ + γ²₂ + …)

$\text{1}\text{2}$

of Matthiessen's rule γ = γ₁ + γ₂ + …, holds when there exist scattering centers of different kinds in the system.     

Electron-exciton inelastic collision cross sections for different semiconductors

The electron-exciton inelastic collision cross sections for the different semiconductors CdS, ZnO, CdSe, Si, Cu₂O, CuCl, CuBr and CuI have been calculated in the Glauber approximation. The transitions 1s–2s, 1s–3s, 1s–2p and 1s–3p have been considered. The calculations are carried out as function of the different available values of $\text{σ =}\text{m}{}^1{}_{\mathrm{e}}\text{m}{}^1{}_{\mathrm{h}}$ where m¹_e and m¹_h are, respectively, the electron a corresponding semiconductors.     

ДлИны Boлн и Bepoятнocти пeppexoдoв Для иэoэлeктpoннoЙ пocлeдoбaтэльнocти киcлoпoдa

Energies of the transitions 1s²2s²2p⁴?1s²2s2p⁵?1s²2p⁶ belonging to the isoelectronic sequence of oxygen have been calculated. The Hartre-Fock energy and the correlation energy, as well as relativistic corrections, were taken into account. The results have been compared with experimental data. Agreement was found to be good, thus suggesting that the $\text{(}\text{1}\text{Z}\text{)-}\text{expansion}$ converges rapidly. Perturbation theory was used for calculations of transition probabilities for the transitions 1s²2s²2p⁴?1s²2s2p⁵?1s²2p⁶ of the isoelectronic sequence of oxygen. The results may be useful in interpreting soft X-ray line radiation from these transitions, as observed in the solar corona and in high-temperature laboratory-generated plasmas.     

Exact Fermi energy,susceptibilities, and their singularities for an electron gas in a uniform magnetic field at T = 0 °K

Exact analysis is presented to derive the magnetic response functions and their singularities of free-electron gas in a uniform magnetic field of arbitrary strength at T = 0 °K. The newly defined functions, Λ_μ(s) = ∑₀^[s])(s ? n)^μ of $\text{μ =}\text{?1}\text{2}\text{,}\text{1}\text{2}\text{,}\text{3}\text{2}$, are employed to obtain the Fermi energy, magnetization, and susceptibility as functions of B. It is revealed that the spin susceptibility is composed of two parts, χ_s1 and χ_s2, where χ_s2 is purely oscillatory diamagnetic. A graphical method of finding the Fermi energy ?_F(B) as a function of B has been obtained. The system is shown to become totally one-dimensional electron gas in the field B greater than $\text{B}{}_{\mathrm{\downarrow }}\text{= (2ηn)}{}^{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}$ and the total energy satisfies $\text{E}{}_{\mathrm{t}}\text{=}\text{1}\text{3}\text{?}{}_{\mathrm{F}}\text{(B)N}$. The obvious extension of the present theory to the Bloch electrons on the ellipsoidal constant energy surface is also discussed.     

Lithium mobility in the layered oxide Li1−xCoO2

The Li⁺-ion chemical diffusion coefficient in the layered oxide Li_0.65CoO₂ has been measured to be $\text{D}\text{?}\text{= 5 × 10}{}^{\mathrm{?12}}$ m² s^?1 by three independent techniques: (1) from the Warburg prefactor, (2) from the transition frequency for semi-infinite to finite diffusion lengths in steady-state ac-impedence measurements and (3) from a modified Tubandt method that uses ac-impedance data to distinguish interfacial and surface-layer resistances from the bulk resistance of the sample. This value and a small increase in D? with (1 ? x) in Li_1?xCoO₂, 0.45 < (1 ? x) < 0.80, compare favorably with the $\text{D}\text{?}\text{= 5}\text{to}\text{7 × 10}{}^{-12}\text{m}{}^2\text{s}{}^{-1}$ obtained by Honders for this system with pulse techniques. A qualitative discussion is presented as to why this composition dependence and why D? for this system is a factor of five larger than that for Li⁺-ion diffusion in Li_xTiS₂.     

Annealing studies on the absorption spectrum of 41K-atoms trapped in an argon matrix

Argon crystals were doped with 0.2 ppm of ⁴¹K through the nuclear reaction ⁴⁰Ar (n, β^-) ⁴¹K. The absorption spectrum from 300 nm to 800 nm was measured as a function of the annealing temperature. Absorption ← 4²s_{$\text{1}\text{2}$} transition of the free atom could be bands corresponding to the 4²p_{$\text{1}\text{2}$}, _{$\text{3}\text{2}$} ← 4²s_{$\text{1}\text{2}$} and 5²p_{$\text{1}\text{2}$}, _{$\text{3}\text{2}$} ← 4²s_{$\text{1}\text{2}$} transition of the free atom could be observed. The absorption bands depend strongly on the annealing temperature. An increase in the annealing temperature results in a blue shift of the absorption bands.     

Oscillator strengths of the first forbidden lines of rubidium

The oscillator strengths of the 5s-4d first forbidden lines of rubidium at 5165 Å were determined by performing CW tunable dye laser absorption measurements. Measured oscillator strengths of 8.06±0.48×10^-7 and 5.38±0.31×10^-7 for the ²D_{$\text{5}\text{2}$} and ²D_{$\text{3}\text{2}$} states, respectively, are compared with previously published values.     

Mössbauer spectroscopy study of iodine and tellurium atoms in solid argon

Mössbauer effect studies were performed on the nucleogenic ¹²⁵Te and ¹²⁹I monomers formed by the decay of their respective parents ^125mTe and ^129mTe embedded in solid argon at 4.2 K. Rare-gasmatrix-isolation (RGMI) and ion implantation techniques were combined to produce those extremely diluted Mössbauer emitters. The ¹²⁵Te spectrum is composed of a quadrupole split component with splitting $\text{e}{}^2\text{qQ}\text{2}\text{= 9.2(4)}\text{mm}\text{s}$ and isomer shift $\text{IS = + 0.35(5)}\text{mm}\text{s}$, and a single line component with $\text{IS = +0.15(5)}\text{mm}\text{s}$ with respect to a ZnTe absorber. They are attributed to Te⁰ and Te^?1 species, respectively. The ¹²⁹I spectrum is composed of a single quadrupole split component with $\text{e}{}^2\text{qQ = ?685(20) MHz and IS = +0.75(4)}\text{mm}\text{s}$ with respect to a ZnTe source. This species is attributed to I⁰. Two novel single-line absorbers with high f values at RT were developed for the Te and I experiments, e.g. Mg₃TeO₆ and Na₅IO₆. Based on our results for Te⁰ and Te^?1 and on relativistic Dirac-Slater atomic calculations, a new IS calibration curve under the form of a nonlinear relationship of IS versus the number of p holes (h_p) in the closed shell configuration of 5s²5p⁶ is established for ¹²⁵Te. The IS data of the I⁰ monomer are used to refine the IS(h_p) relationship for ¹²⁹I. From these new calibration curves values are deduced for the change in mean-squared charge radius Δ〈r²〉 = 3.4(3) 10^?3fm² for ${}^{125}\text{Te and Δ〈r}{}^2\text{〉 = 19.9(7) 10}{}^{\mathrm{?3}}\text{fm}{}^2$ for ¹²⁹I, respectively. The origin of the quadrupole interaction and the experimental features of this RGMI-implantation-Mössbauer emission spectroscopy are fully discussed.     

Turbulence measurements in a resonance tube

Experimental investigations of acoustically induced turbulence in a resonance tube have been performed. Frequency (f) and sound pressure level (I_p) effects have been studied. Measurements were made at various spatial locations on loops and nodes. Sampled data were processed to estimate the characteristics of turbulence. It is found that the acoustically induced turbulence appears when I_p exceeds 160 dB under the experimental conditions of f = 680–2740 Hz and I_p = 160–166 dB. The turbulent spectrum (F) and the wave number (κ) are found to satisfy a power law F ∝ K^s with $\text{s ? ?1·6}\text{to}\text{? 2·1}$. The r.m.s. turbulent velocity ($\text{u}\text{?}$) is experimentally found to have an $\text{I}{}_{\mathrm{p}}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ dependence, yet is relatively insensitive to the variation of f. Throughout the whole measuring range of f and I_p, the rate of energy dissipation per unit mass (ε) is estimated to be in the order of 10⁶–10⁷cm²/s³.