Evaluation of the exothermicity of the chemi- ionization reaction Nd plus O -> NdO+ + e(-) and neodymium oxide, carbide, dioxide, and carbonyl cation bond energies

摘要

The exothermicity of the chemi-ionization reaction, Nd + O NdO+ + e(-), has been indirectly determined by measuring the thermochemistry for reactions of the lanthanide metal neodymium cation (Nd+) with O-2, CO2, and CO and reactions of NdO+ with CO, O2, and Xe. Guided ion beam tandem mass spectrometry was used to measure the kinetic energy dependent product ion cross sections for these reactions. NdO+ is formed through a barrierless exothermic process when the atomic metal cation reacts with O-2 and CO2. All other reactions are observed to be endothermic. Analyses of the kinetic energy dependences of these cross sections yield 0 K bond dissociation energies (BDEs) for several species. The 0 K BDE for Nd+-O is determined to be 7.28 +/- 0.10 eV from the average of four independent thresholds. This value is combined with the well-established Nd ionization energy to indicate an exothermicity of the title reaction of 1.76 +/- 0.10 eV, which is lower and more precise than literature values. In addition, the Nd+-C, ONd+-O, and Nd+-CO BDEs are determined to be 2.61 +/- 0.30, 2.12 +/- 0.30, and 0.30 +/- 0.21 eV. Additionally, theoretical BDEs of Nd+-O, Nd+-C, ONd+-O, and Nd+-CO are calculated at several levels for comparison with the experimental values. B3LYP calculations seriously underestimate the Nd+-O BDE, whereas MP2 and coupled-cluster with single, double-and perturbative