Search

High-resolution laser excitation spectroscopy has been used to record the à 2E-X 2A1 electronic transition of SrCH3 in a laser ablation/molecular jet source. Transitions arising from the K′=1←K″=0, K′=0←K″=1, and K′=2←K″=1 subbands have been observed and assigned. The data were modeled with 2E and 2A1 symmetric top Hamiltonian matrices in a Hund’s case (a) basis, using a least squares fitting program. Rotational and fine structure parameters for the à 2E state were determined. A comparison of the spin-orbit energy separation in the à 2E state to other strontium containing free radicals showed that the Jahn-Teller effect is negligible. The spin-rotation constants for the à 2E state were calculated using the pure precession model and were found to be in good agreement with the experimentally determined parameters. These calculations suggest that the à 2E state of SrCH3 is not entirely of p orbital character. The rotational constants were used to estimate the structural parameters of SrCH3 in the à 2E state. The strontium-carbon bond length was found to decrease by ∼0.006 Å, and the hydrogen-carbon-hydrogen bond angle opened by ∼0.8° compared to the X 2A1 state, similar to the geometry changes observed for CaCH3. [ABSTRACT FROM AUTHOR]

The intensities of charge exchange recombination spectroscopy (CXRS) of α particles colliding with the hydrogen atoms in the neutral beam injection (NBI) are calculated by solving the rate equations including electron collision processes in the quasi-static state approximation. The effects of electron collision processes on the CXRS signals for He+(n=4→3) at λ=468.6nm in various plasma conditions are discussed, and it is found that these effects can increase the CXRS signals by 50% for electron density ne≥1015cm-3. However, their importance decreases with the increasing of NBI energy. For the short pulse of NBI, the influences of electron collision processes can be neglected for ne≤1014cm-3. Furthermore, the spectra of He+(n→n') are present for the plasma conditions of HT-7 tokamak. [ABSTRACT FROM AUTHOR]

Abstract: The high-resolution spectrum of the transition of BaOH has been recorded using laser excitation spectroscopy. The BaOH molecules were synthesized through the reaction of Ba atoms with H2O2 in a Broida-type oven. Rotational and fine structure parameters have been determined for the state through a combined least-squares fit with the millimeter-wave pure rotational data of the state. The Λ-doubling constants observed for the state are in poor agreement with the predictions of the pure precession model of the interactions between the and the states of BaOH. In addition to the bands of the transition, three bands located at ∼11443cm−1, ∼12013cm−1 and ∼12505cm−1, respectively, were also observed and analyzed but their vibrational and electronic assignments are not clear. Possible assignments of the three unidentified bands are discussed based on the derived spectroscopic constants and the vibrational assignments of previous low-resolution work. [Copyright &y& Elsevier]

Abstract: The and states of SrOH were investigated using optical–optical double-resonance (OODR) spectroscopy. Rotational and fine structure parameters have been determined for these two states through a combined least-squares fit of the current OODR data along with the OODR data of the transition, the optical data of the transition and the millimeter-wave pure rotational measurements of the state. The spin–rotation constant, γ, of the state was found to be 0.002653cm−1, which is two orders of magnitude smaller than that of the state (−0.1447cm−1). This small γ value suggests that this state arises from a Sr+ atomic orbital of mainly 6sσ character. This atomic orbital assignment is also supported by the large rotational constant observed in the state and the similarity of the molecular constants to those of the state of CaOH. The rotational energy levels of the state of SrOH were found to be largely perturbed, which prohibited the accurate determination of the spin–rotation constant in this state. This perturbation is most likely due to an interaction with a 2Σ vibronic component of the nearby state. [Copyright &y& Elsevier]

A laser ablation/pulsed molecular jet system has been used to record high-resolution laser excitation spectra of the [image omitted]2A'- [image omitted]2A' transition of CaSH and the [image omitted]2A'- [image omitted]2A', [image omitted]2A''- [image omitted]2A', and [image omitted]2A'- [image omitted]2A' transitions of SrSH. The rotationally-resolved data were analysed using an asymmetric top Hamiltonian (A-reduction) to determine rotational and fine structure parameters. A combined fit of all the newly measured and the previously recorded spectroscopic data for both CaSH and SrSH was performed. In the excited states observed in this study, both species were found to have a bent geometry. The spin-rotation parameters were analysed in terms of the pure precession and unique perturber approximations. In the excited electronic states of SrSH, the large spin-rotation interaction was found to cause perturbations between the Ka = 0 and 1 levels within each state. In the [image omitted]2A' and [image omitted]2A'' states of both species, the metal-sulfur bond length was found to decrease relative to the ground state, which is consistent with previous observations of other calcium and strontium radicals. [ABSTRACT FROM AUTHOR]

WITHDRAWN TO APPEAR IN SPECIAL ISSUE IN 2007 [ABSTRACT FROM AUTHOR]

High-resolution laser excitation spectroscopy has been used to record the à 2E-X 2A1 electronic transition of SrCH3 in a laser ablation/molecular jet source. Transitions arising from the K′=1←K″=0, K′=0←K″=1, and K′=2←K″=1 subbands have been observed and assigned. The data were modeled with 2E and 2A1 symmetric top Hamiltonian matrices in a Hund’s case (a) basis, using a least squares fitting program. Rotational and fine structure parameters for the à 2E state were determined. A comparison of the spin-orbit energy separation in the à 2E state to other strontium containing free radicals showed that the Jahn-Teller effect is negligible. The spin-rotation constants for the à 2E state were calculated using the pure precession model and were found to be in good agreement with the experimentally determined parameters. These calculations suggest that the à 2E state of SrCH3 is not entirely of p orbital character. The rotational constants were used to estimate the structural parameters of SrCH3 in the à 2E state. The strontium-carbon bond length was found to decrease by ∼0.006 Å, and the hydrogen-carbon-hydrogen bond angle opened by ∼0.8° compared to the X 2A1 state, similar to the geometry changes observed for CaCH3. [ABSTRACT FROM AUTHOR]

Abstract: The state of CaOH was investigated using optical–optical double resonance spectroscopy. A combined least-squares fit of the double resonance transition data along with optical transition data and the millimeter-wave pure rotational data of the state was performed using an effective Hamiltonian. The spin–rotation constant was determined for the state for the first time. An analysis of these constants showed that the Ca–O bond length and spin–rotation parameter of the state have the smallest values of all the observed 2Σ+ states of CaOH. This evidence suggests the assignment of the state as arising from a Ca+ atomic orbital of mainly 5sσ character. This atomic orbital assignment was shown to be consistent with both previous work on CaF and recent theoretical calculations on CaOH. [Copyright &y& Elsevier]

Abstract: The electronic transition of SrNH2 has been recorded at high resolution using laser-ablation/molecular jet techniques. Transitions arising from the and levels have been observed. The data have been analyzed using the S-reduced asymmetric top Hamiltonian to determine rotational and fine structure parameters. The spin–rotation constants of the state were calculated using the pure precession model. These values were found to be in relatively good agreement with the experimentally determined parameters, however slight differences suggest that the unpaired electron in the state is not entirely of p orbital character. A molecular structure was also determined for the state of SrNH2. The strontium–nitrogen bond was found to decrease by 0.011Å while the H–N–H bond angle was found to increase by 2.5° between the and states. A small positive inertial defect was calculated for the state, indicating that the molecule is planar. [Copyright &y& Elsevier]

Abstract: The laser-induced excitation spectrum of the transition of SrCCH has been recorded at high resolution. A rotational analysis has been performed yielding rotational and fine structure parameters for the à state. In addition, a vibrational frequency for the Sr–C stretch (ν 3) in the à 2Π state has been determined. Using the rotational constant of the à state, the Sr–C bond length was determined to be 2.43Å, which is ∼0.03Å shorter than in the ground state. A comparison of the Λ-doubling constant p, to those of the other alkaline-earth acetylides suggests that SrCCH and CaCCH appear to follow the pure precession model unlike MgCCH. Finally, a search for the transition was negative, as with CaCCH, suggesting that the state may be predissociative. [Copyright &y& Elsevier]

High-spin states in 139Pm are investigated via the 116Cd(27A1, 4n)139Pm fusion-evaporation reaction at a beam energy of 120 MeV. The previously reported level scheme has been modified because of identifications of some linking and doublet transitions. The revised yrast πh11/2 band obviously undergoes πh11/2 → π(h11/2)³ → π(h11/2)³ ⊗ πh11/2 ⊗ ν(h11/2)-2 band crossings at ħω = 0.45 and 0.39 MeV. Two negative-parity dipole bands have been assigned as π(h11/2) ⊗ ν(h11/2)-2 and πh11/2 ⊗ ν(h11/2)-4 configurations, respectively, can be considered as examples of magnetic rotational bands. [ABSTRACT FROM AUTHOR]

The high spin states of 112In have been investigated with in-beam γ-ray spectroscopic methods using the 110Pd(7Li,5n)112In reaction at a beam energy of 50 MeV. A level scheme with three band structures has been established and their configurations are discussed. The positive-parity dipole band has been assigned as a magnetic rotation band. Particle-rotor model calculations have also been performed to interpret the rotational structures in 112In. [ABSTRACT FROM AUTHOR]