Mass spectrometric investigation of gaseous YbH, YbO and YbOH molecules

Abstract

The high-temperature gaseous molecules YbH, YbO and YbOH have been identified and their thermochemistry investigated by the Knudsen effusion mass spectrometry technique coupled with a controlled pressure gas inlet system. Solid ytterbium monosilicide and disilicide samples were made to react in the Knudsen cell with H2(g) and H2(g)/O2(g); in these conditions, several gaseous species (Yb, YbO, YbH, YbOH, SiO, SiO2, H2O) were formed under equilibrium conditions. The temperature dependences of the partial pressures of the observed gaseous molecules were analyzed to derive the Yb--X bond energies (X = H, O, OH). Selected values are D0o(Yb--H) = 179.4 +/- 2.0 kJ mol(-1), D0o(Yb--O) = 384 +/- 10 mol(-1) and D0o(Yb--OH) = 322 +/- 12 kJ mol(-1), and Delta(at)H0o(YbOH) = 746 +/- 12 kJ mol(-1). Density functional theory (DFT) calculations were also performed. Experimental and computational results are discussed and compared to previous data when available. The SiO/SiO2 high-temperature gaseous equilibrium was also observed.

The electronic configurations of LnX (Ln=La–Eu, X=O, S, Se, Te): A FON–DFT investigation

“…The LnO and LnS molecules have been studied at ligand field theory (LFT) [1][2][3][4][5], intermediate neglect of differential overlaps (INDO) [6], density functional theory (DFT) [7][8][9][10][11][12][13][14][15][16][17][18] and configuration interaction/coupled cluster with singles and doubles (CISD/CCSD) [19][20][21] levels with pseudopotential or frozen core approximations, while the theoretical literatures on LnSe and LnTe are few [15]. Wang and Schwarz in 1995 [8] studied the properties of LnO (Ln = La, Eu, Gd, Yb) and found a 4f 13 r 1 /4f 14 r 0 mixed ground state for YbO, which is stabler than either 4f 13 r 1 or 4f 14 r 0 .…”

Time-dependent relativistic density functional study of Yb and YbO

“…To describe the electron interactions consistently, the 4s4p4d5s5p core electrons have to be correlated as well. More seriously, the high angular momentum and the compactness of the 4f orbitals result in very large differential relativistic and electron correlation effects when the f-occupation changes; (4) The large relativistic effects have to be treated variationally. The nonadditivity of relativistic and electron correlation effects renders the calculation very difficult.…”

“…Among the diatomic lanthanide molecules, the lanthanide monoxides LnO are most extensively investigated, both by laser or mass spectroscopy experiments [1][2][3][4] and by theoretical methods including ligand field theory (LFT) [1][2][3]5,6] , relativistic density functional theory (DFT) [4,[7][8][9][10][11][12] and ab initio CISD (configuration interaction with singles and doubles) in conjunction with relativistic pseudopotentials [13][14][15] . Although LFT based on the purely ionic model Ln 2+ O 2− arising from Ln 2+ 4f n 6s (n = 0-14 for La-Lu, except Eu and Yb) or Ln 2+ 4f n+1 (for Eu and Yb) has been quite successful, the effective charge distribution of LnO is best represented as Ln δ + O δ − , i.e., a polar (partially ionic) covalent bond [7,9] .…”

A gas‐inlet system coupled with a Knudsen cell mass spectrometer for high‐temperature studies

“…9 These experiments were carried out using two preliminary study of the inflow of H 2 -O 2 mixtures in the KC is presented.…”

“…1,2 Within the framework of this technique the reactivity between a solid and a permanent gas has been the object of investigations aimed at detecting new molecular species and deriving their thermodynamic properties (examples can be found in Refs. [3][4][5][6][7][8][9] or at investigating the vaporization features of materials of technological interest under various chemical environments (e.g. Ref.…”