No abstract

No abstract

level. The agreement between the experimental results and the ab initio predictions is otherwise excellent, giving credence to the spectral assignments for A12H6 and the mixed dimers. The removal of symmetry results in much richer IR spectra and thus the assignment of new bands to the mixed dimer, say BGaH6, in a mixture of B2H6 and Ga2H6 should be possible based on Table II. In fact the exchange reaction, B2H6 + Ga2H6 -* 2BGaH6, should be experimentally accessible and provide new and interesting information regarding the chemistry of these systems. ConclusionsThe structures of the hexahydrides of boron, aluminum, and gallium are all diborane-like. The d10 electrons in gallane incompletely shield the nucleus, making it a stronger Lewis acid than might be otherwise expected. It was found necessary to split the valence orbitals to obtain a reasonable description of the gallium hydrides. The dissociation energies of diborane, dialane, digallane, and alaborane, gallaborane, and gallalane are remarkably similar when correlation is taken into account, suggesting that the decreased Lewis acidity of alane and gallane are compensated for by their increased hydridic bonds. Alaborane, gallaborane, and gallalane spectra are predicted to be very rich as a consequence of the loss of symmetry and should allow experimental detection of these mixed hexahydrides in the appropriate mixtures of diborane, dialane, and digallane.

No abstract

We report a detailed investigation of nonresonant laser-induced thermal acoustics (LITA) for the single-shot measurement of the speed of sound (v(S)) in an oven containing room air. A model for the speed of sound that includes important acoustic relaxation effects is used to convert the speed of sound into temperature. A reference LITA channel is used to reduce uncertainties in v(S). Comparing thermocouple temperatures with temperatures deduced from our v(S) measurements and model, we find the mean temperature difference from 300 to 650 K to be 1% (+/-2sigma). The advantages of using a reference LITA channel are discussed.