High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

Abstract

An assessment of high-temperature mass spectrometry and of sources of inaccuracy is made. Experimental, calculated, and estimated cross-sections for ionization of atoms and inorganic molecules typically present in high-temperature vapors are summarized. Experimental cross-sections determined for some 56 atoms are generally close to theoretically calculated values, especially when excitation–autoionization is taken into account. Absolute or relative cross-sections for formation of parent ions were measured for ca. 100 molecules. These include homonuclear diatomic and polyatomic molecules, oxides, chalcogenides, halides, and hydroxides. Additivity of atomic cross-sections supplemented by empirical corrections provides fair estimates of molecular cross-sections. Causes of uncertainty are differences in interatomic distances and in shapes of potential energy curves (surfaces) of neutral molecules and of molecular ions and tendency toward dissociative ionization in certain types of molecules. Various mass spectrometric procedures are described that render the accuracy of measured thermodynamic properties of materials largely independent of ionization cross-sections. This accuracy is comparable with that of other techniques applicable under the conditions of interest, but often only the mass spectrometric procedure is appropriate at high temperatures.

Thermochemistry of Neutral and Charged Vapor Complexes over NaBr-LnBr3 Systems

“…12) for NaBr and were computed by a method of statistical thermodynamics in the 'rigid rotator -harmonic oscillator' approximation on basis of molecular parameters obtained by theoretical study. , 41 (42) 3-11 (2012) 10 (Ln) and the associated basis sets: cc-pVTZ for Na and pVTZ (7s 6p 5d / 5s 4p 3d) for Ln and (14s 10p 2d 1f / 3s 3p 2d 1f) Br.…”

Formation of γ'-Ni₃Al via the Peritectiod Reaction: γ + � (+ Al₂O₃) = γ' (+ Al₂O₃)

“…[35][36][37] . The partial pressures were determined as a function of temperature by Knudsen effusion-cell mass spectrometry, KEMS, where p(i) inside the effusion-cell is determined from the measured intensity of a representative ion beam, I i , and absolute temperature, T, according to the relationship: p(i) = I i T / S i (where S i is the instrument sensitivity factor) [38] . The need to determine S i and absolute partial pressure was removed in this study with a multiple effusion-cell vapor source (with three effusion-cells), multi-cell KEMS, which allows the relative partial pressure between samples in adjacent effusion-cells to be determined directly [39][40][41][42] .…”

Vaporization and Thermodynamics of Glass-Forming Oxide Melts: Mass Spectrometric Study and Modeling

“…It was evidently shown [1] that Knudsen effusion mass spectrometric method is extremely powerful tool to study vaporization processes and thermodynamic properties of glass-forming oxide systems since this approach was suggested first [2] for the investigation of individual compounds. Recent advantages and improvements of this experimental technique may be found in [3]. Unfortunately one of the latest reviews on mass spectrometric study of inorganic compounds and materials at high temperatures [4] did not draw too much attention to glass-forming materials.…”