Investigation of Inorganic Systems at High Temperature by Mass Spectrometry

Abstract

High-temperature mass spectrometry (hitherto at temperatures between I000 and 2500 " K and at pressures between 10-3 and 10-12 atm) has already made possible the identiJication of many previously unknown and unpredicted diatomic and polyatomic molecular species. The present paper deals with the investigation of many oxides, of halides, and of carbon molecules and intermetallic molecules. An apparatus for the production and investigation of molecular beams is described. Knudsen cells permit the production of molecular beams under equilibrium conditions; in special cases the "doubleoven" type of Knudsen cell is used. Thermodynamic and kinetic quantities such as d H; values, dissociation energies, and ionization cross sections of the species investigated are given.

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

“…Mass spectrometric studies in high-temperature chemistry, aimed at the determination of thermodynamic properties for condensed phases and for gaseous molecules, mostly make use of Knudsen effusion (see, e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14]17,20,21,[24][25][26][27][28]) or of vapor transport supersonic molecular beam sampling methods (see, e.g., [15,19]) to generate the molecular beam that is to be analyzed with respect to the nature and the pressure of the gaseous chemical entities present in the cell containing the sample.…”

“…For diatomic molecules, such as H 2 , N 2 , O 2 , S 2 , Se 2 , Te 2 , and dimeric alkali halides, review of early measurements [5,8] had already shown that the cross-section is but ca. 50 % higher than for the atom or the monomer, rather than twice as large.…”

“…• Comparison of ion intensities integrated against time with mass losses: -for known amounts of the system studied and of an inert substance, often Ag or Au, added to the former [1,4,8,13]; -for the main species of a system studied [4,8,94,[194][195][196][197]. Ionization cross-section measurements as a function of energy for different fragmentation channels were so determined for C 60 and C 70 [195,196].…”

“…During this period, a number of review papers have appeared describing instruments and experimental procedures in high-temperature mass spectrometry (HTMS) . Synopses of the results have also been presented [3][4][5][6][8][9][10]14,17,18,[20][21][22][23][24][25][26][27][28]. Data obtained by this technique for individual compounds, whether gaseous or in the condensed phase, are incorporated in tabulations of dissociation energies [29][30][31][32][33][34][35][36][37][38], of thermodynamic properties [32][33][34][35][36][37][38], and of ionization potentials [30,39,40].…”

Investigation of New Intermetallic Bonds and Molecules by Knudsen Effusion Mass Spectrometry Integrated with ab Initio Calculations

“…Since its beginnings, the Knudsen Effusion Mass Spectrometry (KEMS) technique was recognized to be a powerful tool to discover new molecules and to investigate their energetic properties, such as dissociation and atomization energies [1]. In the last 50 years, many previously unknown molecular species were identified by KEMS in the high temperature vapors produced under conditions close to thermodynamic equilibrium, and their atomization energies determined.…”