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Cross sections for He+ H 2 collisions are reported for rovibrational states near dissociation at translational energies less than 1000 cm −1 . In contrast to our previously reported cross sections for lower-lying initial rotational states, the excited rotational states near dissociation give rise to shape resonances for energies between 0.001 and 1 cm −1 . The emergence of these resonances with increasing rotational level is opposite to the trend found for He+ CO where the shape resonance strength decreases with rotational level for low-lying states. Quasiresonant energy transfer and low energy excitation thresholds are also discussed and it is found that there are 11 rovibrationally excited states that are stable against collision at ultracold temperatures.

The two most recently published potential energy surfaces (PESs) for the HeH 2 complex, the so-called MR (Muchnick and Russek) and BMP (Boothroyd, Martin, and Peterson) surfaces, are quantitatively evaluated and compared through the investigation of atom-diatom collision processes. The BMP surface is expected to be an improvement, approaching chemical accuracy, over all conformations of the PES compared to that of the MR surface. We found significant differences in inelastic rovibrational cross sections computed on the two surfaces for processes dominated by large changes in target rotational angular momentum. In particular, the H 2 (ν = 1, j = 0) total quenching cross section computed using the BMP potential was found to be a factor of 1000 larger than that obtained with the MR surface. A lesser discrepancy persists over a large range of energies from the ultracold to thermal and occurs for other low-lying initial rovibrational levels. The MR surface was used in previous calculations of the H 2 (ν = 1, j = 0) quenching rate coefficient and gave results in close agreement with the experimental data of Audibert et al. which were obtained for temperatures between 50 and 300 K. Examination of the rovibronic coupling matrix elements, that are obtained following a Legendre expansion of the PES, suggests that the magnitude of the anisotropy of the BMP potential is too large in the interaction region. However, cross sections for elastic and pure rotational processes obtained from the two PESs differ typically by less than a factor of two. The small differences may be ascribed to the long-range and anharmonic components of the PESs. Exceptions occur for (ν = 10, j = 0) and (ν = 11, j = 1) where significant enhancements have been found for the low-energy quenching and elastic cross sections due to zero-energy resonances in the BMP PES which are not present in the MR potential.

In this article Tricia Clark shares her experience of the ways in which post‐16 provision can be further developed to meet the needs of young people with autistic spectrum disorders. She emphasises the need, in accordance with SENDA 2001, for further education colleges to anticipate the needs of all disabled students in order to accommodate them. She concludes that the key to inclusive provision is flexibility.