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.

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Different spectroscopic methods are used for the measurement of flame temperature. This report compares measurement of temperature profiles for atmospheric premixed H^/ 02/^2^a m " lnar flames using the methods of: (1) Raman scattering (N£, vibrational and rotational temperatures), (2) line reversal (D-line of Na, electronic temperature), and (3) line ratio (OH, rotational temperature). Two separate burner designs are considered. To obtain the most accurate comparison possible, all measurements were made with the same burners and auxiliary gas-feed system. The theory for each technique is summarized and the sensitivity, accuracy, and convenience are compared. Necessary corrections are discussed. In general, the results indicate very good agreement (better than 98 percent) between the various methods for certain combinations of flame composition and burner type. 1.

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