Dissociation energies of the molecules CrPO2(g) and CrO(g) by high-temperature mass spectrometry

Abstract

The gaseous molecule CrPO, has been investigated in the course of a high-temperature massspectrometric Knudsen-cell study of the vapours over an europium-chromium-phosphorus-oxygen system. From the enthalpy of the equilibrium reaction CrPO,(g) = CrO(g) + PO(g) and appropriate ancillary data, the atomization energy of this molecule has been determined. In addition, the dissociation energy of CrO(g) has been obtained through the study of the gaseous exchange reactions W03(g) + Cr(g) = W02(g) + C r a g ) EuO(g) and and compared with previous results. 436.2 f 8.9 kJ mol-'. was derived as: L\H&[CrPO,(g)] = 217.6* 13.0 kJ mol-'. The dissociation energies obtained are: (CrP02) = 1438.4* 12.2 kJ mol-', and D F ( C r 0 ) =The appearance potential of CrPO,(g) was determined to be 8.0 f 0.5 eV, and the heat of formation

Ionization potentials and bond energies of TiO, ZrO, NbO and MoO

“…5 The proposed best values from these studies were IP͑NbO͒ϭ7.91͑2͒ eV and IP͑TiO͒ϭ6.82͑2͒ eV. Later Sappey et al 6 obtained IP͑TiO͒ϭ6.819͑6͒ eV from a multiphoton ionization photoelectron spectrum in excellent agreement with the previous measurements.…”

“…Using electron impact ionization Balducci et al 5 measured the ionization efficiency of NbO as a function of electron energy and determined the IP͑NbO͒ by extrapolation as 7.0Ϯ0.5 eV. In the same year Dyke et al 3 used high temperature photoelectron spectroscopy to determine the IP͑NbO͒ more directly and found a much higher value of 7.91Ϯ0.02 eV.…”

Metal oxide and carbide thermochemistry of Y+, Zr+, Nb+, and Mo+

“…The only exception is for NbO where PM based their chosen value of 7.93Ϯ0.26 eV on the single study of Shchukarev et al 10 More recent work by Balducci et al provides D 0 ͑NbO͒ϭ8.02Ϯ0. 19 eV, 11 which we adopt here. Most available IE͑MO͒ values are electron impact values that come from high-temperature mass spectrometry studies.…”

Thermodynamic study of some chromium‐containing gaseous molecules by high‐temperature mass spectrometry

“…Studies of chromium‐containing salts are experimentally more difficult, since high temperatures are required. The existence and stability of chromium phosphate, CrPO 2 , and barium and europium chromates, BaCrO 2 , BaCrO 3 , BaCrO 4 and EuCrO 2 , have been reported by Balducci and co‐workers1,2 and by Kudin et al 3. The apparent stability of these gaseous species indicates that further studies of the gas‐phase reaction of chromium oxides CrO and CrO 2 with various anion‐ and cation‐forming oxides are of interest.…”