By virtue of this agreement it is unexpected that comparison with the experimental D(0) or D(e) dissociation energies (zero-point vibrational effects are negligible in this context) reveal errors larger than 0.1 eV for Ga(2), Ge(2), and Sb(2). An exception is Te(2) where theoretical results scatter by 0.085 eV. Relativistic and non-relativistic results for the dissociation energy D(e) are in close agreement with each other and previously published data, provided non-relativistic or scalar-relativistic results are corrected for spin-orbit contributions taken from the literature. Extended basis sets up to pentuple zeta are employed and energies extrapolated to the complete basis-set limit. We report results of non-relativistic and two-component relativistic single-reference coupled-cluster with single and double and perturbative triple excitations treatments for the 4p-block dimers Ga(2) to Br(2), the 5p-block dimers In(2) to I(2), and their atoms. Preliminary experiments on the in situ formation of H(2)O(g) in the Knudsen cell by the introduction of controlled gaseous H(2)/O(2) mixtures are also presented. The results obtained for the dissociation energies of the diatomic molecules PbO(g), GeO(g), GaH(g), and AuH(g) compare well with the literature data giving confidence in the reliability and versatility of the method. The capabilities of the device have been tested with four gas-solid systems: PbO(s) + O(2)(g), GeO(2)(s) + O(2)(g), Ga(s) + H(2)(g) and Au(s) + H(2)(g), by studying the relevant high-temperature equilibria. ![]() ![]() Mixtures of two different gases can be introduced into the cell, controlling their partial pressures independently. By selecting the gas flow from the external reservoir the pressures of the gases inside the Knudsen cell can be quantitatively controlled over three orders of magnitude, approximately from 10(-8) to 5.10(-5) bar. A gas-inlet system coupled with a Knudsen effusion mass spectrometer has been developed to study at high temperature the interaction of solids and vapors with reactive permanent gases, such as H(2) and O(2), directly introduced into the cell from external low-pressure reservoirs (pressure range: 10(-4) < p < 1 bar).
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