Reaction cross sections by time profile measurements under crossed-beam conditions: The Ca(3P,1D)+N2O→CaO*+N2 reaction

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Abstract
The collision energy dependence of the Ca(3P,1D)+N2O→CaO*+N2 reaction has been determined by time profile measurements under crossed‐beam conditions. A narrow velocity distribution N2O beam collides with a pulsed beam of excited metastable Ca(3P,1D) atoms, produced by low‐voltage discharge. Time‐of‐flight spectra were used to monitor both the reagent translational and the chemiluminescence yield of the CaO* product (green arc band). The chemiluminescence cross section for excitation of the CaO green arc bands decreases with increasing translational energy with 1D reagent, but increases for the 3P state. The combination of a narrow velocity distribution of the supersonic N2O beam with short pulses of the Ca* beam leads to collision energy resolution of the order of magnitude of a few meV. This could be important not only for determining high resolution reaction thresholds, but perhaps for the onset of quantum effect in the total reaction cross section.