Rev. Sci. Instrum. 50, 1002 (1979] were used with either Re or spring-steel gaskets to compress the samples, which consisted of cryogenically loaded Xe along with Fe powder (<20 |xm grain size) and less than 10 volume % fine-grained ruby (<5 |xm grain size); the latter is used for pressure calibration [H. K. Mao, P. M. Bell, J. W. Shaner, J. Steinberg, J. Appl. Phys. 49, 3276 (1978)]. Samples were heated inside the diamond cell by means of a Quantronix 117 continuous-wave Nd:YAG laser operated in the TEM00 mode, with average temperatures ranging from 1860 (±180) to 3080 (±300) K being documented by imaging spectroradiometry [R. Jeanloz and A. Kavner, Philos. Trans. R. Soc. London Ser. A 354, 1279(1996]. 20. Diffraction patterns were obtained at high pressures and room temperature (before and after laser heating) using a Rigaku 12 kW/mm 2 rotating anode source of monochromatized Mo Ka x-rays. The diffraction patterns were collected in angular-dispersive mode with film and analyzed by methods described elsewhere [J. H. Nguyen and R. Jeanloz, Rev. Sci. Instrum. 64, 3456 (1993)].Epoxides are versatile building blocks for organic synthesis. However, terminal epoxides are arguably the most important subclass of these compounds, and no general and practical method exists for their production in enantiomerically pure form. Terminal epoxides are available very inexpensively as racemic mixtures, and kinetic resolution is an attractive strategy forthe production of optically active epoxides, given an economical and operationally simple method. Readily accessible synthetic catalysts (chiral cobaltbased salen complexes) have been used for the efficient asymmetric hydrolysis of terminal epoxides. This process uses water as the only reagent, no added'solvent, and low loadings of a recyclable catalyst (<0.5 mole percent), and it affords highly valuable terminal epoxides and 1,2-diols in high yield with high enantiomeric enrichment.Asymmetric catalysis provides access t o addition to carbonyl compounds (2). Both optically active epoxides either by oxygen-strategies have been developed t o varying atom transfer to alkenes ( J ) or by carbene degrees, but significant gaps still exist in the scope of these methodologies. For example,

The dilatometric investigation in the temperature range of 2-28K shows that a first-order polyamorphous transition occurs in the orientational glasses based on C60 doped with H2, D2 and Xe. A polyamorphous transition was also detected in C60 doped with Kr and He. It is observed that the hysteresis of thermal expansion caused by the polyamorphous transition (and, hence, the transition temperature) is essentially dependent on the type of doping gas. Both positive and negative contributions to the thermal expansion were observed in the low temperature phase of the glasses. The relaxation time of the negative contribution occurs to be much longer than that of the positive contribution. The positive contribution is found to be due to phonon and libron modes, whilst the negative contribution is attributed to tunneling states of the C60 molecules. The characteristic time of the phase transformation from the low-T phase to the high-T phase has been found for the C60-H2 system at 12K. A theoretical model is proposed to interpret these observed phenomena. The theoretical model proposed, includes a consideration of the nature of polyamorphism in glasses, as well as the thermodynamics and kinetics of the transition. A model of non-interacting tunneling states is used to explain the negative contribution to the thermal expansion. The experimental data obtained is considered within the framework of the theoretical model. From the theoretical model the order of magnitude of the polyamorphous transition temperature has been estimated. It is found that the late stage of the polyamorphous transformation is described well by the Kolmogorov law with an exponent of n=1. At this stage of the transformation, the two-dimensional phase boundary moves along the normal, and the nucleation is not important.Comment: 29 pages, 14 figures, added references, corrected typo

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Lifetime measurements on perturbed levels of NO(B 2Π) and precise term energy of the NO(a 4Π) stateThe zero-pressure radiative lifetime ofthe NO(B 2 IT) state has been measured over the vibrational level range v = 0-6. Laser-induced fluorescence was the technique chosen for this study, using two different sources of ground state NO. In one case, photodissociation of N02 at 193 nm was used to obtain a range of ground state vibrational levels, from which selected rotational levels were then pumped to the B I IT state, while in the second case, NO in v = 0 was directly pumped. The two methods of preparing the excited state gave identical lifetime results. The data show a linearly decreasing lifetime with increasing vibrational level and to a good approximation the lifetimes, are given by 7(f1S) = 2.00-0. 193v. Recent calculations for the B-X system show excellent agreement with experiment at low v, and an increasing discrepancy with increasing vibrational level, the experimental lifetimes decreasing more rapidly than the calculated ones. The lifetime values fall within the 0.85-2.0 f1s range for v = 0-6, and are substantially different from the 2-3 f1s values that are currently quoted.Comparison of the new values with data derived from absorption studies shows good agreement even for the high vibrational levels. Absolute Einstein A factors are presented for the v' = 6 progression.

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