Atomization enthalpy and enthalpy of formation of gaseous Si2 and Si3 from mass spectrometric equilibrium measurements

Abstract

Articles you may be interested inAtomization enthalpy and enthalpy of formation of gaseous Si4 from mass spectrometric equilibrium measurements J. Chem. Phys. 99, 7998 (1993); 10.1063/1.465676Mass spectrometry of and standard enthalpies of formation of gaseous sodium tetrachloroaluminate and its dimer J. Chem. Phys. 87, 654 (1987); 10.1063/1.453560 Mass spectrometric determination of the heats of formation and atomization energies of the molecules Ge2N and GeSiNRecent experimental and theoretical studies have allowed us to calculate new thermal functions for the Si 2 and Si 3 molecules. We have determined the atomization enthalpies and enthalpies of formation of Si 2 and Si 3 from mass spectrometric data and have combined them with reevaluated previously published mass spectrometric data using a consistent set of ionization cross sections and thermal functions. The selected atomization enthalpy and enthalpy of formation for the Si 2 molecule are ⌬H a,0 ϭ319Ϯ7 and ⌬H f ,0 ϭ584Ϯ7 kJ mol Ϫ1 , the corresponding values for Si 3 are 705Ϯ16 and 649Ϯ16 kJ mol Ϫ1 . Reevaluated values for Si 4 are 1151Ϯ22 and 654Ϯ22 kJ mol Ϫ1 . Experimental literature values ͑Neumark and co-workers͒ for the electron affinities of Si 2 -Si 4 have been combined with the present results to obtain enthalpies of formation and binding energies for the anions Si 2Ϫ -Si 4 Ϫ . The experimental atomization enthalpies are compared to recent theoretical studies.

Electronic and geometric structures of Sin– and Sin+ (n = 2–10) clusters and in comparison with Sin

“…However, in order to test the accuracy of this method, we present our results for Si 2-8 clusters in Table 1 compared with those obtained by 6-31G* and MP4/6-31G* calculations [32]. In addition, Gingerich, Schmude and coworkers have obtained experimental binding energies on Si [2][3][4][5][6][7][8] [33,34,[36][37][38][39], which provide a calibration for the theoretical work. In the method we are comparing to, each ground state structure was optimized with the standard 6-31G* basis set (valence double-zeta sp plus a set of d-type polarization functions on each silicon atom).…”

Electronic structure and thermochemical properties of silicon‐doped lithium clusters LinSi0/+, n = 1–8: New insights on their stability

“…[49] Similarly, the heat of formation at 0 K of the Si 2 ( 3 R g À ) of 140.4 kcal/mol is in good agreement with the experimental value of 139.6 AE 1.7 kcal/mol (584 AE 7 kJ/mol). [50] Because of the lack of available experimental data, this agreement for the diatomic Li 2 and Si 2 lends us a confidence in the thermal functions calculated for other clusters, and allows an estimate on the accuracy of the calculated results, that is expected to be AE 2.0 kcal/mol.…”

Molar atomization enthalpies and molar enthalpies of formation of GeSi, GeSi2, Ge2Si, and Ge2Si2by Knudsen-effusion mass spectrometry

“…(12) Si(g), (12) Ge 2 (g), (6) and Si 2 (g), (15) were taken from the literature. The thermal functions for the (germanium + silicon) gaseous species were calculated by using the harmonic-oscillator rigid-rotor approximation.…”