A modified additivity rule for the calculation of electron impact ionization cross-section of molecules ABn

Differential ionization cross-section of hydrogen bromide

In this study, the relative single and double differential ionization cross-section of the hydrogen bromide molecule and their fragmented ions (HBr⁺, Br⁺, H⁺) have been theoretically evaluated. In the single differential ionization cross-sections, the loss of incident electron energies (W) at 100 eV, 200 eV, and 500 eV is calculated. The double differential ionization cross-section of the HBr molecule is determined for secondary electron energy (e) and different incident scattering angles (θ). The differential ionization cross-sections of the hydrogen bromide molecule were investigated for the first time.The derived results of the HBr molecule are not only important in spectrometry but may also be interesting for atmospheric sciences.

Electron impact ionization cross sections of hydrogen fluoride molecule

Partial and total ionization cross sections of hydrogen fluoride molecule are determined from the ionization threshold to high energy (5 KeV) by using a modified Jain-Khare semiempirical approach. Partial single and double differential cross sections with their sums (total) through direct and dissociative ionization have been also evaluated at fixed primary electron energies 100 eV, 200 eV, and 500 eV. There is no other data for partial ionization cross sections and differential ionization cross sections for comparison. In this paper, the total ionization cross sections data have compared with available experimental data and/or with other theoretical data which are available from intermediate to high energy. It is found that the present result gives a better account for the ionization cross sections up to higher energies.

Determination of the thermodynamic activities of LiF and ThF4 in the Li(x)Th(1-x)F(4-3x) liquid solution by Knudsen effusion mass spectrometry

Knudsen effusion mass spectrometry (KEMS) has been used to investigate the vapour pressure over the molten LiF-ThF4 salt and determine the thermodynamic activity of LiF and ThF4 in the liquid solution. As part of the study, the vaporization of pure LiF and pure ThF4 was examined and the results were compared with the literature values finding a good agreement. Next, the vapour pressure of the LixTh1-xF4-3x liquid solution was investigated by measuring four samples having different compositions (XLiF∼ 0.2, 0.4, 0.6, 0.8 mol%). In order to determine the thermodynamic activities, the vapour pressure of LiF and ThF4 species over the liquid solution, as calculated from our results, were compared with the vapour pressure over the pure LiF(l) and pure ThF4(l) systems. A strong deviation from the Raoult's law was observed, more evident in case of LiF species, in agreement with the predictions by our thermodynamic model.

Differential, partial and total electron impact ionization cross sections for SF6

Single and double differential ionization cross sections for the production of ions resulting from dissociative, single and double ionization of SF(6) by electron impact have been calculated using a semiempirical formulation based on the Jain-Khare approach. In addition, triple differential cross sections have been obtained for some of the doubly charged fragment ions at an incident electron energy of 100, 150, and 200 eV, respectively, and a fixed scattering angle of 30 degrees. As no previous data seem to exist for differential cross sections we have derived from these differential cross sections corresponding partial and total ionization cross sections from threshold up to 900 eV and compared those with the available theoretical and experimental data.

Thermochemical aspects of proton transfer in the gas phase

The beginning of the twentieth century saw the development of new theories of acidity and basicity, which are currently well accepted. The thermochemistry of proton transfer in the absence of solvent attracted much interest during this period, because of the fundamental importance of the process. Nevertheless, before the 1950s, few data were available, either from lattice energy evaluations or from calculations using the emerging molecular orbital theory. Advances in mass spectrometry during the last 40 years allowed studies of numerous systems with better accuracy. Thousands of accurate gas-phase acidities or basicities are now available, for simple atomic and molecular systems and for large biomolecules. The intrinsic effect of structure on the Brønsted basic or acidic properties of molecules and the influence of solvents have been unravelled. In this tutorial, the basics of the thermodynamic principles involved are given, and the mass spectrometric techniques are briefly reviewed. Advances in the design and measurements of gas-phase superacids and superbases are described. Recent studies concerning biomolecules are also evoked.