We report properties of single-wire proportional chambers and multiple-wire ionization chambers filled with liquid xenon. Proportional multiplication is seen for anode fields > 10{sup 6} volts/cm (anode-cathode voltage> 1 kV for a 3.5-{micro}-diam anode wire). The efficiency for detecting ionizing radiation is {approx} 100%. The time resolution of the chambers is {+-} 10{sup -7} sec. We attained a spatial resolution of {+-} 15 {micro} with a multiwire ionization chamber, considerably better than that of any other real-time particle detector.

Recent the orbital symmetry rules have been shown to apply to hetero-atom systems such as nitrone thermal cycloaddition reactions and the thermal and photochemical aziridine ring cleavage at the C-C bond. The concerted photocyclization is disrotatory and the reverse thermal cleavage is conrotatory in these molecules with four {pi} electrons. In contrast to the azomethine ylide-aziridine system, the stereochemistry of the nitrone photocyclization to oxaziridine can only be observed on carbon and nitrogen atoms because the oxygen atom has lone pair electrons instead of substituents. For the reverse thermal ring opening of oxaziridine to the nitrone, the two possible conrotatory motions of C-O bond cleavage should result in a mixture of the cis and trans-isomers of the nitrone, in contrast to the photoclosure which should be stereospecific.

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