Jean Drowart

Mass spectrometric determination of the dissociation energies of the molecules AgAu, AgCu, and AuCu

Abstract : The vapors issuing from mullite and Grpahite Knudsen cells containing pure metals and alloys of the triad Cu-Ag-Au have been analyzed mass spectrometrically. From the experimental ratios of diatomic to monoatomic species and the vapor pressures of the elements, the following dissociation energies are obtained: Cu2 = 43.2 + or - 2.2 kcal; AgAu = 47.6 + or - 2.2 kcal; Ag2 = 35.7 + or - 2.2 kcal; AgCu = 40.7 + or - 2.2 kcal; Au2 = 51.9 + or - 2.2 kcal; AuCu = 54.3 + or -2.2 kcal. These are based on H (sup vap) (sub 298) = 81.1, 68.4 and 87.5 cal/mole for Cu, Ag and Au where dissociation energy of AgAu depends on the value for Cu, and dissociation energy of AgAu and AuCu on Au. The uncertainties quoted do not include the uncertainty in Delta H (sup vap). These results are interpreted in terms of chemical bonding theories. The relation between bonding in the gas and in the pure condensed phases is again observed. Furthermore, a previously unobserved qualitative relation between the dissociation energy of the asymmetrical molecule and the heat of formation of the corresponding alloys is indicated.

Mass Spectrometric Study of the Systems Boron—Carbon and Boron—Carbon—Silicon

Abstract : The systems B-C and B-C-Si were investigated mass-spectrometrically. The atomization energy of the newly identified molecules BC2, B2C, BCSi, BSi2, BC and BSi are 294, 254, 247, 174, 107 and 68 kcal/mole respectively. The atomization energy of SiC2, Si2C and SiC was redetermined.

Thermodynamic Study of Tin Sulfide and Lead Sulfide Using a Mass Spectrometer

A mass‐spectrometric investigation of the vapor in equilibrium with solid SnS, solid PbS, and a mixture of SnS and PbS has yielded the following reaction enthalpies: SnS(s)→SnS(g)ΔH2980=52.6±1.6 kcal/mole2SnS(s)→Sn2S2(g)56.5±5.0PbS(s)→PbS(g)55.7±1.62PbS(s)→Pb2S2(g)66.6±5.0      PbS(g)→Pb(g)+12S2(g)28.8±2.6Sn2S2(g)→2SnS(g)48.7±5.0Pb2S2(g)→2PbS(g)44.8±5.0      SnPbS2(g)→SnS(g)+PbS(g)46.5±5.0. The dissociation energies of gaseous SnS and PbS were determined to be D00(SnS) = 110.1±3.0 kcal/mole, D00(PbS) = 79.1±2.8 kcal/mole and are compared with the spectroscopically determined values.

Thermodynamic study of tin selenide and tin telluride using a mass spectrometer

Abstract : In a mass spectrometric investigation of the vapor in equilibrium with solid SnSe and solid SnTe, a number of reaction enthalpies were measured and from known thermochemical data, the following thermochemical values were calculated: enathalpy of formation at 298 degrees of SnSe and SnTe; dissociation energy of SnSe and SnTe; enthalpy of dimerization at 298 degrees of SnSe, SnTe, and SnTe2. The dissociation energies were compared to the available spectroscopic data.

Mass spectrometric determination of dissociation energies of gaseous indium sulphides, selenides and tellurides

The atomization energies : D∘0(InS)= 67.9 ± 3.5; D∘0(InSe)= 57.7 ± 3.5; D∘0(InTe)= 50.6 ± 3.5; ΔH∘0(In2S)= 148.2 ± 4.0; ΔH∘0(In2Se)= 132.7 ± 4.0; ΔH∘0(In2Te)= 110.8 ± 4.0; ΔH∘0(In2S2)= 224.5 ± 10.0; ΔH∘0(In2Se2)= 200.5 ± 10.0; ΔH∘0(In2Te2)= 173.2 ± 10.0 and ΔH0(InTe2)= 107.4 ± 4.0 kcal/mole were determined. The heat of formation of In2S3(s) was deduced : ΔH∘298, ƒ(In2S3)=–82.8 ± 4.5 kcal/mole. The dissociation energies D∘0(Se2)= 73.6 ± 2.0 and D∘0(Te2)= 55.9 ± 2.0 kcal/mole were also measured.

Mass Spectrometric Study of the Gaseous Molecules above AgSn, AuSn, and CuSn Alloys

Mass spectrometric technique has been employed to analyze the molecular beams effusing from mullite Knudsen cells containing Sn and alloys of Cu, Ag, and Au with Sn. From the experimental intensities of monatomic and diatomic species and the vapor pressure of Sn, the following dissociation energies are obtained: D0∘(Sn2)=45.8±4 kcal/mole,D0∘(AgSn)=31.6±5 kcal/mole,D0∘(AuSn)=57.5±4 kcal/mole,D0∘(CuSn)=41.4±4 kcal/mole.

Mass spectrometric determination of the dissociation energy of the molecules MgO, CaO, SrO and Sr2O

Abstract : The diatomic molecules Sc2, Y2, La2 and YLa have been identified mass spectrometrically in the vapors above condensed scandium, yttrium, lanthanum and Y-La alloys respectively. Their dissociation energies are Sc2 25.9 = 5, Y2 37.3 = 5, La2 57.6 = 5 and YLa 47.3 =5 kcal/mole.

Mass spectrometric study of the photoionization of carbon disulphide in the wavelength interval 125–60 nm

The ionization and dissociative ionization of CS2 by photon impact have been investigated mass spectrometrically in the wavelength interval λ= 125–60 nm. The efficiency curves for formation of CS+2, CS+, S+ and S+2 are presented and discussed.From the thresholds for formation of the fragment ions, values for the bond dissociation energy D°(S—CS, g, 0 K)= 432.1 ± 2.0 kJ mol–1, the dissociation energy of CS, D°(CS, g, 0 K)= 712.1 ± 2.3 kJ mol–1, the enthalpy of formation of CS, ΔHof(CS, g, 0 K)= 273.9 ± 2.2 kJ mol–1 and the ionization potential of S2, i.p.(S2)= 9.38 ± 0.03 eV are deduced and compared with literature values.

Zur Thermodynamik von Selendampf: Massenspektrometrische Untersuchungen mit der elektrochemischen Knudsen-Zelle

Eine elektrochemische Knudsen-Zelle mit galvanischen Festkorperketten der Art Ag/AgJ /Ag2Se, wobei AgJ ein praktisch reiner Ionenleiter fur Silberionen ist, wird im Temperaturbereich von 200—450 C verwendet, um einen Selen-Dampfstrahl zu erzeugen, der dann im Massenspektrometer analysiert wird. Die Kombination dieser Techniken ergibt folgende Moglichkeiten: 1. Die Verdampfungsgeschwindigkeit des Selens kann coulometrisch bestimmt werden. Hierdurch ergibt sich eine Moglichkeit zur Druck-Eichung des Massenspektrometers. 2. Das chemische Potential des Selens ist bekannt und kann bei konstanter Temperatur in weiten Grenzen variiert werden. Es ist daher moglich, die verschiedenen Selenmolekule Sex getrennt zu untersuchen und ihr Verhalten bei Elektronenstos-Ionisation — speziell die Fragmentation — zu studieren. Mit Hilfe dieser Methode werden im Selendampf folgende Teilchen eindeutig identifiziert: Se2, Se3, Se4, Se5, Se6, Se7, Se8 und relative Ionisierungsquerschnitte, Partialdrucke und genaue thermodynamische Daten ermittelt.

MASS SPECTROMETRIC DETERMINATION OF THE STABILITY OF GASEOUS MOLYBDITES, TUNGSTITES, MOLYBDATES AND TUNGSTATES OF MAGNESIUM, CALCIUM, STRONTIUM AND TIN

A number of gaseous ternary oxides have been identified by mass spectrometry, while vaporizing MgO, CaO, SrO and SnO2+Sn from Mo and W crucibles. The stabilities of the gaseous molecules SrMoO3, CaWO3, SrWO3, MgMoO4, CaMoO4, SrMoO4, MgWO4, CaWO4, SrWO4, SnWO4 and Sn2WO5, were deduced from the measurements.