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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information , 1215 Jefferson Davis Highway. Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid 0MB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)Air Force Research Laboratory/Directed Energy Directorate,Kirtland Air Force Base, New Mexico 87117-5776 SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release; distribution is unlimited State-to-state rotational relaxation of carbon monoxide (CO) has been studied using an IR double resonance technique. Individual rotational lines of the (2-0) vibrational overtone band were pumped by a pulsed tunable IR laser and the subsequent evolution of the v=2 rotational population distribution was monitored by the absorption of a tunable cw IR laser via the (3-2) band transitions. Both the excitation and probe lasers were linearly polarized, with linewidths that were narrower than the CO Doppler width. Consequently, alignment and velocity relaxation effects were observed in these measurements. A data set consisting of 54 time-dependent rotational state population profiles was acquired. The full CO-CO rotational relaxation matrix, which consists of state-to-state rate constants for rotational levels up to J = 29, was deduced from computer simulations of the data. Scaling and fitting laws were used to provide parametric representations of the rate constants. The three most common models, modified exponential gap (MEG), statistical polynomialexponential gap (SPEG), and energy corrected sudden with exponential-power gap (ECS-EP) were investigated. We concluded that the SPEG law best reproduced the CO-CO rotational energy transfer data. A propensity to preserve the CO parity in rotational energy transfer was observed for collisions where the amount of energy transferred was small. Hence, even AJ processes were favored for transitions between levels with low I values. For nearsingle collision events a correlation was noted between the amount of rotational energy transferred and the degree of velocity distribution relaxation. This correlation yielded insights regarding the energy transfer dynamics. State-to-state rotational relaxation of carbon monoxide (CO) has been studied using an ir double resonance technique. ...

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