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Abstract: We have compiled a set of electron collision cross sections for HBr. It will be useful for a fluid modeling of HBr plasmas together with transport coefficients in both DC and RF, E and E × B fields. The calculation made use of a Monte Carlo technique. The transport coefficients are rather unstructured because the total cross section resembles that of a constant collisonal frequency model. Additional measurements of swarm parameters are required in order to obtain more acurate set of cross sections. [Copyright &y& Elsevier]

Abstract: Time-dependent wave packet calculations have been performed for the O(1D)+HBr→BrO+H and O(1D)+HBr→OH+Br reactions. The state-to-state and state-to-all reaction probabilities for total angular momentum J =0 have been calculated. The probabilities for J >0 have been estimated from the J =0 results by using J-shifting approximation based on a capture model. Then, the integral cross-sections and thermal rate constants have been calculated. The calculations show that the initial state-selected reaction probabilities are dominated by resonance structures. The reaction cross-section also manifests resonances and is a decreasing function of the translational energy and the thermal rate constants are not sensitive to the temperature. [Copyright &y& Elsevier]

The orientation of free HRgX molecules arising from photodissociation of hydrogen halide molecules HX on rare gas clusters Rgn is investigated in a new experimental arrangement: the rare gas cluster beam with HX molecules in the surface is intersected by two focussed laser beams at one point, where it additionally interacts with a weak electrostatic field. The possibility to generate and successively orient this new class of molecules is analyzed for a couple of new candidate molecules. We observe oriented HXeCl molecules, while HXeBr and HKrCl escaped our detection scheme, as was expected from the analysis. Details of the measured kinetic energy distributions (KED) of H-fragment atoms from the HXeCl photodissociation are analyzed in terms of the Xe–H vibrational structure on the calculated potential energy surface of HXeCl. Finally, a strong indication for observation of HXeH molecules is found in the fragment KED peak around 0.35 eV. These symmetric molecules arise from the dissociation of more than one HX molecule on the cluster and are consistently observed for all HX–Xen systems with X=Cl,Br,I. [Copyright &y& Elsevier]

Spectra of the dications derived by photoionisation from HBr, N2, CO, NO, O2, H2S, CO2, OCS, CS2, N2O and SO2 in the valence energy range are presented. The spectra are taken by a method which accepts all photoelectrons irrespective of energy or emission angle, and offers a resolution a few tens of meV, depending on the energy. The spectra seem to be relatively unaffected by molecular autoionisation. The full electron–electron energy distributions in double photoionisation of these molecules show autoionisation of atomic fragments in several cases. Brief descriptions of the double photoionisation spectra of the polyatomic molecules C2H2, CH4, NH3, C2H4, C4H6, C6H6 and C6F6 are also given. An approximate relationship between excitation energies of dications and orbital energies taken from photoelectron spectra using Koopmans’ theorem is proposed. It is suggested that relative intensities of double photoionisation bands for different final states may be connected to details of the electron–electron correlations in the parent molecules. [Copyright &y& Elsevier]

• Photoelectron angular distributions of the HBr+ X state have been measured. • Photoelectron anisotropy parameters affected by autoionizing Rydberg states. • X state threshold electron spectrum exhibits partially resolved rotational structure. • Rydberg states observed in ion yield. A double-imaging photoelectron-photoion spectrometer and synchrotron radiation have been used to measure the HBr+ X 2Π 3/2 v + = 0, 1, 2 and the 2Π 1/2 v + = 0 state photoelectron angular distributions, as characterized by the anisotropy parameter β , the total ion yield, and the threshold photoelectron spectrum. Particular attention has been focussed on the photon energy range between the 2Π 3/2 and the 2Π 1/2 spin–orbit components of the ground ionic state. This region encompasses Rydberg states, belonging to series converging onto the upper 2Π 1/2 ionization limit, which may decay by autoionization into the 2Π 3/2 ionization continuum. A detailed study has been performed on the effects of autoionization on the 2Π 3/2 v + = 0 state photoelectron angular distributions. The observed energy dependent variations in the β -values exhibit a regular pattern that correlates with excitation into members of a very broad d-type Rydberg series. Additional rapid variations in the β -parameters, which occur over a narrow energy range, appear to coincide with sharp autoionizing Rydberg states belonging to s, p and d series. The present experimental results for the HBr+ X 2Π 3/2 v + = 0 state photoelectron anisotropy parameter are compared to previously reported theoretical predictions and to earlier studies of the Kr+ 4p5 2P 3/2 state β -parameter. The threshold photoelectron spectrum of the X 2Π 3/2 v + = 0 band exhibits partially resolved rotational structure. A simulation of this structure yields an ionization threshold of 11.6673 ± 0.0010 eV, which is consistent with previous measurements. [ABSTRACT FROM AUTHOR]