Classical trajectory calculations are used to investigate the energy transfer properties of HO2ndash;He collisions under conditions where HO2is initially excited to energies near dissociation. The emphasis in this investigation is on determining the dependence of vibrational energy transfer characteristics on heat bath temperature, total molecular energy, and total molecular angular momentum. Vibrational energy transfer is a function of all three variables. Energy transfer averages, correlation coefficients, and energy transfer cross sections are used to determine the energy transfer mechanism. Evidence is found for all types of energy transfer, but the specific mechanism for a particular ensemble is highly dependent on the initial variables. At fixed vibrational energy and heat bath temperature, the magnitude of the average vibrational energy transferred per collision Verbar;lang;Dgr;Eprime;rang;Verbar; increases with increasing molecular angular momentum. At fixed initial molecular angular momentum and heat bath temperature, minus;lang;Dgr;Eprime;rang; increases as the total energy in the molecule increases, except for very low values of initial angular momentum. Increasing the heat bath temperature for fixed values of the other initial variables decreases the magnitude of lang;Dgr;Eprime;rang;. The relative importance of weak and strong collisions in governing the energy transfer characteristics is discussed. In particular, the probability density function for vibrational energy transfer is not well represented by a simple lsquo;lsquo;exponential downrsquo;rsquo; model. A double exponential function is required to represent the long tail of the distribution adequately. Total vibrational energy transer cross sections determined from vibrational energy transfer histograms are weak functions of total energy, total angular momentum, and heat bath temperature. They are systematically higher than the corresponding Lennardhyphen;Jones cross sections.
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