Electron impact excitation of tetrasulfur S4 molecule

Electron impact excitation of tetrasulfur S₄ molecule is investigated in this work using R-matrix method. The twelve low-lying electronic states are used in close-coupling expansion to represent the target states, and the integral cross sections for elastic scattering and excitation into the six lowest electronic states are calculated.     

Electron (positron) impact excitation (2p state) of lithium at intermediate energies

In this work, studies have been carried out to investigate theoretically the electron (positron)-impact-induced 2s → 2p lithium (Li) transition at 20 and 60 eV using the coupled-channel optical method (CCOM). The inelastic differential cross sections (DCS) together with the reduced Stokes parameters ( $\bar P_1$ , $\bar P_2$ , $\bar P_3$ ) and other parameters such as the alignment (γ, $\bar P_l$ ), orientation (L _⊥) and coherence parameters (P ⁺) are reported in the present calculations. Comparison is made with other available theoretical and experimental measurements.     

Resonant excitation of a new valence state in N2 by electron impact

A new valence state which lies below the first Rydberg state has been observed in N₂, in the 11.3 to 12.1 eV energy range, using an electron impact technique. This state is only excited from 1.3 to ～3 eV above its threshold through a short lived resonance. Some levels are not clearly resolved but their presence is deduced from the resonant profiles of their differential cross sections. A perturbation in the relative intensities of the C³Π_u vibrational levels is observed when this new state is excited.     

Semiempirical calculation of the atomic characteristics of the 2p5 3d, 4d, and 2p5ns (n = 3–10) configurations of neon

Semiempirical calculation of the fine-structure parameters, the intermediate-coupling wave functions, and the gyromagnetic ratios is carried out for a number of configurations of the neon atom in the single-configuration approximation. Comparative analysis of the results obtained is performed. __________ Translated from Optika i Spektroskopiya, Vol. 99, No. 4, 2005, pp. 558–561. Original Russian Text Copyright ? 2005 by Semenov, Kapel’kina, Tsygankova, Tsygankov.     

Experimental investigation of electron impact excitation of zinc atoms to the 41P1 state

Polarization analysis version of the electron-photon coincidence technique was applied to completely determine quantum state of zinc atoms excited to the 4¹P₁ state by electron impact. We report first experimental values of Stokes parameters and Electron Impact Coherence Parameters (EICPs) for incident electron energy 80 eV.     

Cascading through the 1P1 (1s)(2p) state of fluorine

The ¹P₁ (1s)(2p) state of He-like fluorine produced in a foil-excited fluorine beam is shown to decay with a $\text{t}{}^{\mathrm{<mtext>-3</mtext><mtext>2</mtext>}}$ time function. This behavior is identical to that recently reported for oxygen beams and thus demonstrates that there is no strong Z dependence for this time behavior.     

Bound states of D(2p)–D0 systems supersymmetric p-cycles

We discuss some issues related to D(2p)–D0-branes with background magnetic fluxes, respectively, in a T-dual picture, Dp–Dp-branes at angles. In particular, we describe the nature of the supersymmetric bound states appearing after tachyon condensation. We present a very elementary derivation of the conditions to be satisfied by such general supersymmetric gauge configurations, which are simply related by T-duality to the conditions for supersymmetric p-cycles in .     

Selective excitation of the 62 D 3/2 state of the atomic thallium beam

The absorption of the tunable narrow-band laser radiation with λ = 276.9 nm at the 6² P _1/2 → 62 D _3/2 transition in the atomic thallium beam is experimentally studied. The isotopic selectivity and efficiency of the excitation of the 6² D _3/2 state is investigated. The splittings between the ²⁰³Tl and ²⁰⁵Tl isotopes were found to be Δv = 0.98 and 1.25 GHz for the transitions with the nuclear momenta F = 1 → F = 1, 2 and F = 0 → F = 1, respectively, which is sufficient for a relatively high isotopic selectivity of the 6² D _3/2 state excitation with the subsequent ionization for the laser separation of the thallium isotopes. The effects that lead to the broadening of the resonance and a decrease in the selectivity are analyzed. The main contribution is related to the field broadening by the laser radiation, which limits the mean laser power density.     

23 excitation of Li+ by electron impact

The 1¹S→2³S excitation of Li⁺ has been studied in the Coulomb-Born-Oppenheimer approximation. The differential and the total cross sections are given at double the threshold energy.     

Cross-section measurements of (n, 2n) and (n, p) reactions on 124,126,128,130,131,132Xe in the 14 MeV region and theoretical calculations of their excitation functions

The reaction cross-sections of ¹²⁴Xe(n, 2n)¹²³Xe, ¹²⁶Xe(n, 2n)¹²⁵Xe, ¹²⁸Xe(n, 2n)¹²⁷Xe, ¹³⁰Xe(n, 2n)^129mXe, ¹³²Xe(n, 2n)^131mXe, ¹³⁰Xe(n, p)¹³⁰I, ¹³¹Xe(n, p)¹³¹I, and ¹³²Xe(n, p)¹³²I were measured at the 13.5, 13.8, 14.1, 14.4, and 14.8 MeV neutron energies. The monoenergetic neutrons were generated via the ³H(d,n)⁴He reaction at the China Academy of Engineering Physics using the K-400 Neutron Generator with a solid ³H-Ti target. A high-purity germanium detector was employed to measure the activities of the product. The reactions ⁹³Nb(n, 2n)^92mNb and ²⁷Al(n, α)²⁴Na were adopted for neutron flux calibration. The cross sections of the (n, 2n) and (n, p) reactions of the xenon isotopes were obtained within the 13–15 MeV neutron energy range. These cross-sections were then compared with the IAEA-exchange format (EXFOR) database-derived experimental data, together with the evaluation results of the CENDL-3, ENDF/B-VIII.0, JENDL-4.0, RUSFOND, and JEFF-3.3 data libraries, as well as the theoretical excitation function obtained using the TALYS-1.95 code. The cross-sections of the reactions (except for the ¹²⁴Xe(n, 2n)¹²³Xe and ¹³²Xe(n, p)¹³²I) at 13.5, 13.8, and 14.1 MeV are reported for the first time in this study. The obtained results are beneficial in providing better cross-section constraints for the reactions in the 13–15 MeV region, thus improving the quality of the corresponding database. Meanwhile, these data can also be used for the verification of relevant nuclear reaction model parameters.     

The A2 (n, 3px) Rydberg state of formaldehyde

Pairs of bands were observed in the absorption spectrum of H₂CO, HDCO, and D₂CO in the 1470-1430 Å region which were characterized by well-defined rotational band contours. A band contour synthesis of the observed band envelopes demonstrated that the bands are described by type C selection rules. From the observed intervals and their shifts on deuterium isotope substitution these bands were assigned to quantum additions of ν₅ and ν₆. The symmetry of the upper state was deduced to be ¹A₂ from the vibrational assignment of the bands and their polarizations, while the results from MO theory lead to the orbital assignment n → 3p_x. The electronic transition then is .     

Studies on the ZrO/W(100) surface by means of low-energy electron diffraction and X-ray photoelectron spectroscopy

The low work-function ZrO/W(100) surface was examined with the aim of understanding the reducing mechanism of the work function. Low-energy electron diffraction (LEED) was employed to analyze the surface atomic arrangement, and X-ray photoelectron spectroscopy (XPS) was used to identify the surface chemical condition. The ZrO/W(100) surface was made as follows: (i) around three monolayers of Zr were deposited on a clean W(100) surface, (ii) the sample was heat treated in an oxygen ambience of 1.3x10⁻⁵ Pa for several tens of minutes at 1500 K, and (iii) the sample was flash heated at 2000 K in ultrahigh vacuum (UHV). During heat treatment in O₂, the deposited Zr was oxidized to ZrO₂, and the LEED pattern formed was p(2×1). The work function increased to 5.3 eV. Subsequent flash heating in UHV changed the p(2×1) LEED pattern into a c(4×2) pattern, and transformed ZrO₂ into the so-called Zr–O complex, the oxidized level of which is between ZrO₂ and metallic Zr. A drastic decrease in the work function to 2.7 eV ensued. The angular dependence of XPS showed that the Zr–O complex segregated within a few monolayers at the surface.     

Dissociative excitation cross sections of quartet states of O(II) by electron impact

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 51, No. 5, pp. 738–742, November, 1989.     

Coulomb excitation of neutron-rich Zn isotopes: first observation of the 2(1)+ state in 80Zn

Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 2(1)+ state in 78Zn could be firmly established and for the first time the 2+ --> 0(1)+ transition in 80Zn was observed at 1492(1) keV. B(E2,2(1)+ --> 0(1)+) values were extracted for (74,76,78,80)Zn and compared to large scale shell model calculations. With only two protons outside the Z=28 proton core, 80Zn is the lightest N=50 isotone for which spectroscopic information has been obtained to date. Two sets of advanced shell model calculations reproduce the observed B(E2) systematics. The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni.