Microcanonical thermodynamics and statistical fragmentation of dissipative systems. The topological structure of the N-body phase space

We report a photoelectron spectroscopy and computational study of two simple boron oxide species:  BO- and BO2-. Vibrationally resolved photoelectron spectra are obtained at several photon energies (355, 266, 193, and 157 nm) for the 10B isotopomers, 10BO- and 10BO2-. In the spectra of 10BO-, we observe transitions to the 2Σ+ ground state and the 2Π excited state of 10BO at an excitation energy of 2.96 eV. The electron affinity of 10BO is measured to be 2.510 ± 0.015 eV. The vibrational frequencies of the ground states of 10BO- and 10BO and the 2Π excited state are measured to be 1725 ± 40, 1935 ± 30, and 1320 ± 40 cm-1, respectively. For 10BO2-, we observe transitions to the 2Πg ground state and two excited states of 10BO2, 2Πu, and 2Σu+, at excitation energies of 2.26 and 3.04 eV, respectively. The electron affinity of 10BO2 is measured to be 4.46 ± 0.03 eV and the symmetrical stretching vibrational frequency of the 2Πu excited state of 10BO2 is measured to be 980 ± 30 cm-1. Both density functional and ...

Vibrationally resolved photoelectron spectroscopy of BO- and BO2-: a joint experimental and theoretical study.

Carbon and oxygen K-edge photoionization of the CO molecule

The family of correlation consistent polarized valence basis sets has been extended in order to account for core−core and core−valence correlation effects within the third-row, main group atoms gallium through krypton. Construction of the basis sets is similar to that of the atoms boron through argon, where either the difference between core-correlated and valence-only correlation energies were calculated via configuration interaction (CISD) computations on the ground electronic states of the atoms (named cc-pCVnZ) or the sets were optimized with respect to the core−valence correlation energy and a small weight of core−core correlation energy (cc-pwCVnZ). Due to the correlation of 3d orbitals, added shells of higher angular momentum exponents compared to the valence sets are necessary to describe the core region. The pattern of added core-correlating functions is (1s1p1d1f) for double-ζ, (2s2p2d2f1g) for triple-ζ, (3s3p3d3f2g1h) for quadruple-ζ, and (4s4p4d4f3g2h1i) for quintuple-ζ. Atomic and molecular r...

Systematically convergent correlation consistent basis sets for molecular core-valence correlation effects: the third-row atoms gallium through krypton.

In this work, tin selenide thin films (SnSex) were grown on soda lime glass substrates by selenization of dc magnetron sputtered Sn metallic precursors. Selenization was performed at maximum temperatures in the range 300 °C to 570 °C. The thickness and the composition of the films were analysed using step profilometry and energy dispersive spectroscopy, respectively. The films were structurally and optically investigated by X-ray diffraction, Raman spectroscopy and optical transmittance and reflectance measurements. X-Ray diffraction patterns suggest that for temperatures between 300 °C and 470 °C, the films are composed of the hexagonal-SnSe2 phase. By increasing the temperature, the films selenized at maximum temperatures of 530 °C and 570 °C show orthorhombic-SnSe as the dominant phase with a preferential crystal orientation along the (400) crystallographic plane. Raman scattering analysis allowed the assignment of peaks at 119 cm−1 and 185 cm−1 to the hexagonal-SnSe2 phase and those at 108 cm−1, 130 cm−1 and 150 cm−1 to the orthorhombic-SnSe phase. All samples presented traces of condensed amorphous Se with a characteristic Raman peak located at 255 cm−1. From optical measurements, the estimated band gap energies for hexagonal-SnSe2 were close to 0.9 eV and 1.7 eV for indirect forbidden and direct transitions, respectively. The samples with the dominant orthorhombic-SnSe phase presented estimated band gap energies of 0.95 eV and 1.15 eV for indirect allowed and direct allowed transitions, respectively.

/pdf/thermodynamic-pathway-for-the-formation-of-snse-and-snse2-p2m6yej0rd.pdf

Thermodynamic pathway for the formation of SnSe and SnSe2 polycrystalline thin films by selenization of metal precursors

The HeI (584 A) high resolution photoelectron spectra of As+2, Sb+2, and Bi+2 have been obtained with a high temperature molecular beam source. A pure As2 beam was produced by evaporating Cu3As. Sb2 was generated as a mixture with the atoms and tetramers by evaporating the pure element, while Bi2 was generated as a mixture with only the atoms from the pure element. Vibrational structure was well resolved for the As+2 spectrum. Spectroscopic constants were derived and reported for the related ionic states. In addition, we have carried out relativistic complete active space self‐consistent field followed by multireference single + double configuration interaction calculations on these dimers both for the neutral ground states and the related ionic states. The agreements between the calculated and experimentally derived spectroscopic constants were fairly good, although the calculations tended to underestimate consistently the strength of the bonding in these heavy homonuclear diatomics.

/pdf/photoelectron-spectroscopy-and-electronic-structure-of-2crgen69db.pdf

Photoelectron spectroscopy and electronic structure of clusters of the group V elements. I, Dimers

Vibrationally-resolved HeI (584{angstrom}) photoelectron spectra of the heavy group IV-VI diatomics SnSe, SnTe, PbSe, and PbTe were obtained with a new high temperature molecular beam source. Ionization potentials and spectroscopic constants are reported for all the ionic states observed. Relativistic complete active space MCSCF followed by multireference singles + doubles relativistic CI calculations which included up to 200,000 configurations were made on both the neutral diatomics and their positive ions. Ionization potentials and spectroscopic constants were calculated and were in good agreement with the experimentally-measured values. Relativistic CI potential energy curves were calculated for all the neutral ground states and the ionic states involved. Relativistic effects were shown to play an important role in these heavy diatomics. The {sup 2}{Sigma}{sub 1/2}{sup +} and {sup 2}{Pi}{sub 1/2} states for all four molecular ions showed avoided curve crossings, which resulted in pronounced shoulders in the {Omega} = 1/2 potential energy curves of PbTe{sup +}. Experimentally, autoionization transitions were also observed for the PbTe{sup +} spectrum. The importance of the relativistic effect and chemical bonding in the heavy diatomics are discussed.

/pdf/photoelectron-spectroscopy-and-electronic-structure-of-heavy-26g91gtq40.pdf

K. Balasubramanian

Papers

Photoelectron spectroscopy and electronic structure of clusters of the group V elements. I, Dimers

Photoelectron Spectroscopy and Electronic Structure of Heavy Group IV-VI Diatomics