Data analysis vapor pressure from spectroscopic

A large number of investigations have been reported on spectroscopic, thermodynamic, and other equilibrium properties of chalcogen tetrahalides (e.g., 158-162). They include vibrational spectroscopic analyses of SeCU and TeCU in the solid on the basis of the known structures 89, 373) and in the gas phase (37), equilibrium measurements of SeCU and TeCU in molten salts (f12,376,422), determination of enthalpies of formation 335, 339, 433), other equilibrium studies, and determination of thermodynamic data from vapor pressure measurements, mass spectrometric investigations, conductivity experiments, and thermal phase analysis in the solid (37, 39,203,275, 333, 337, 339, 340, 341, 342,379, 402, 403). 

The thermal functions which would result from the use of the available structural and vibrational Inbformation for the remaining polyatomic species, are biased In the same way as for Sg(g). Some of the necessary Information is derived from condensed phase spectra (rather than gas phase spectra), as with the octamer, the low-valued vibrational frequencies (and possibly the structure) may need to be adjusted. In any event, the use of the existing spectroscopic data (unaltered) leads to calculated entropies which are unreasonable when used in a 3rd law analysis to mesh in the vapor pressure with these thermal functions. 

In this work the products from the thermal dissolution of subbitu-minous Kaiparowitz coal at 427 C in tetralin are examined by spectroscopic ( C, H, NMR), molecular weight (GPC and vapor pressure osmometry (VPO)), and elemental and hydroxyl group analysis. Some of the data presented here are a refinement and extension of data presented in part in earlier work (5). The use of 1,1-dideuterotetralin (5) in con junction with NMR to monitor the time dependence of introduction of deuterium into aliphatic and aromatic structures is presented along with the structural distributions of deuterium transferred. 

The first reliable spectroscopic analysis of saturated sulfur vapor was published by Berkowitz and Marquart [28] who used a combination of a Knud-sen effusion cell with a mass spectrometer and generated the sulfur vapor by evaporating either elemental sulfur (low temperature region) or certain metal sulfides such as HgS which decompose at high temperatures to sulfur and metal vapor. These authors observed ions for all molecules from S2 to Ss and even weak signals for Sg and Sio. From the temperature dependence of the ion intensities the reaction enthalpies for the various equilibria (1) were derived (see Table 1). Berkowitz and Marquart careMly analyzed their data to minimize the influence of fragmentation processes in the ion source of the spectrometer. They also calculated the total pressure of sulfur vapor from their data and compared the results with the vapor pressure measurements by Braune et al. [26]. The agreement is quite satisfactory but it probably... 

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