Applied mass spectrometry

This review presents developments of mass spectrometry in Serbia and the main applications in the physical sciences. The most prominent laboratories involved in this research are The Laboratory of Physical Chemistry and the Laboratory of Atomic Physics, both in The Vinca Institute of Nuclear Sciences, The Institute of Physics of Serbia, and the faculties of Physical Chemistry and Physics in Belgrade. The main topics of investigations are: Analysis of isotopic composition of various elements related to development of methods for enrichment of certain isotopes of importance in nuclear science and technology; Interactions of atoms and molecules with solid surfaces, e.g. surface ionization, adsorption-desorption phenomena; Ion-molecule reactions, and phenomena in electrical discharges; Ionization and dissociation of molecules by monochromatized electron beams (cross sections, thresholds, dissociation energies); High temperature processes and thermodynamic properties of materials of interest in metallurgy and ceramics; Geochronology, geochemistry, hydrology. Besides the quoted activities, there is ongoing active work on the use of mass spectrometry in structural analysis of organic compounds (Faculty of Chemistry and Faculty of Technology in Belgrade), as well as in medicine, environmental sciences and biochemistry, which is beyond of the scope of this review.Serbian Academy of Sciences and Arts, Department of Mathematics, Physics and Geo-Sciences, Conference on Applied Physics in Serbia, May 27-29, 2002, Belgrade, Yugoslavi

Applied mass spectrometry

This review presents developments of mass spectrometry in Serbia and the main applications in the physical sciences. The most prominent laboratories involved in this research are The Laboratory of Physical Chemistry and the Laboratory of Atomic Physics, both in The Vinca Institute of Nuclear Sciences, The Institute of Physics of Serbia, and the faculties of Physical Chemistry and Physics in Belgrade. The main topics of investigations are: Analysis of isotopic composition of various elements related to development of methods for enrichment of certain isotopes of importance in nuclear science and technology; Interactions of atoms and molecules with solid surfaces, e.g. surface ionization, adsorption-desorption phenomena; Ion-molecule reactions, and phenomena in electrical discharges; Ionization and dissociation of molecules by monochromatized electron beams (cross sections, thresholds, dissociation energies); High temperature processes and thermodynamic properties of materials of interest in metallurgy and ceramics; Geochronology, geochemistry, hydrology. Besides the quoted activities, there is ongoing active work on the use of mass spectrometry in structural analysis of organic compounds (Faculty of Chemistry and Faculty of Technology in Belgrade), as well as in medicine, environmental sciences and biochemistry, which is beyond of the scope of this review.Serbian Academy of Sciences and Arts, Department of Mathematics, Physics and Geo-Sciences, Conference on Applied Physics in Serbia, May 27-29, 2002, Belgrade, Yugoslavi

Mass spectrometric study of the dissociative ionization of sulphuryl fluoride by monoenergetic electron impact .1. Heteronuclear fragment ions

The dissociative ionization of sulphuryl fluoride (SO2F2) under electron impact has been examined by using a trochoidal electron velocity selector and a magnetic sector mass spectrometer. The ionization efficiency curves of SO2F2+, SOF2+, SO2F+ and SOF+ have been recorded and the appearance energies of different electronic states of these ions were determined. The results were used to evaluate the dissociation energy D(OSF2-O)=5.32 eV, enthalpies of formation Delta H-f(SO2F)=-427.5 kJ/mol (-4.43eV), Delta H-f(SO2F+)=616 kJ/mol (6.39 eV), Delta H-f(SOF)=-207.5 kJ/mol (-2.15 eV), Delta H-f(SOF+)=710 kJ/mol (7.36 eV) and the ionization energies IE(SO2F)=10.82 eV and IE(SOF)=9.51 eV

Mass spectrometric study of dissociative ionization of the SO2F2 molecule by monoenergetic electron impact .2. SF2+, SF+, SO2+ and SO+ ions

The formation of SF+, SF2+, SO+ and SO2+ fragment ions from dissociative ionization of the SO2F2 molecule has been studied by means of a trochoidal electron velocity selector coupled to a mass spectrometer. The ionization efficiency curves of ions were measured and their appearance energies, both in ground and excited states, were determined, The experimental findings were combined with available thermochemical data to determine the following values: ionization energy IE (SF2) = 10.08 eV; Heat of formation, Delta H-f(SF2+) = 7.01 eV and bond dissociation energy, D(F2S-20) = 9.94 eV. (C) 1997 by John Wiley and Sons, Ltd

Energetics of the ionization and fragmentation of sulfur-containing molecules studied by electron-impact spectroscopy. I. SO2F2

The positive ions produced by the dissociative ionization on SO2F2 were studied using a trochoidal electron monochromator as an electron Sun. The appearance energies of the fragment ions were measured and interpreted in terms of possible fragmentation mechanisms. The results were used to determine the ionization energies and heats of formation of the observed fragment species

Surface ionization study of the hypervalent Li2F molecule

The surface ionization method offers the possibility of measuring ionization energies of atoms, inorganic and organic molecules and clusters, In this study we report the results of the surface ionization of Li2F molecules on a rhenium surface, This work is an attempt to investigate the applicability of the surface ionization technique for the measurment of the ionization energies of hypervalent molelcules at high temperature, There are currently no reliable experimental data for the ionization energy of the Li2F molecule, This molecule has been chosen because previous theoretical calculations have shown that Li2F is a hypervalent (hyperlithiated) molecule with a low ionization energy, The ionization energy was determined to be 5.42+/-0.04 eV

Energetics of the ionization and fragmentation of sulfur-containing molecules studied by electron-impact spectroscopy. I. SO2F2

The positive ions produced by the dissociative ionization on SO2F2 were studied using a trochoidal electron monochromator as an electron Sun. The appearance energies of the fragment ions were measured and interpreted in terms of possible fragmentation mechanisms. The results were used to determine the ionization energies and heats of formation of the observed fragment species

Surface ionization mass spectrometric studies of the Li/C-60 system

We have studied the Li/C-60 system by the surface ionization mass spectrometry. We have investigated a possibility of the Li"C-60 formation via the collisions between Li+ and C-60(-) ions in a plasma state, which was Predicted by an ab initio molecular dynamics simulation. The LiC60 complex was unambiguously observed. Our results do not allow direct determination of the LiC60 structure but indicate that Li is inside the C-60 cage. We have determined the ionization potential of Li"C-60 complex (TP = 5.9 +/- 0.1 eV), which agrees well with the calculated value of the IP of Li"C-60

Anatase TiO(2) single crystals with a large percentage of reactive facets

Owing to their scientific and technological importance, inorganic single crystals with highly reactive surfaces have long been studied. Unfortunately, surfaces with high reactivity usually diminish rapidly during the crystal growth process as a result of the minimization of surface energy. A typical example is titanium dioxide (TiO2), which has promising energy and environmental applications. Most available anatase TiO(2) crystals are dominated by the thermodynamically stable {101} facets (more than 94 per cent, according to the Wulff construction), rather than the much more reactive {001} facets. Here we demonstrate that for fluorine-terminated surfaces this relative stability is reversed: {001} is energetically preferable to {101}. We explored this effect systematically for a range of non-metallic adsorbate atoms by first-principle quantum chemical calculations. On the basis of theoretical predictions, we have synthesized uniform anatase TiO(2) single crystals with a high percentage (47 per cent) of {001} facets using hydrofluoric acid as a morphology controlling agent. Moreover, the fluorated surface of anatase single crystals can easily be cleaned using heat treatment to render a fluorine-free surface without altering the crystal structure and morphology.Hua Gui Yang, Cheng Hua Sun, Shi Zhang Qiao, Jin Zou, Gang Liu, Sean Campbell Smith, Hui Ming Cheng & Gao Qing L