Vibrationally State Specific Relaxation Measurements for Highly Vibrationally Excited Oxygen: Are Quantum States Important in the Atmosphere?

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WPC 2 B V J Z Courier T ? x x x x 6 X @ K X @ Apple LaserWriter IINT APLASIIN.PRS x @ h h h h tX @ #| x 2 Abstract for ATM-9300074 The stimulated emission pumping (SEP)technique has enabled the study of highly vibrationally excited molecules. Such investigations are important because there is now considerable evidence for an efficient production mechanism for highly vibrationally excited oxygen molecules in the stratosphere and mesosphere. Recent measurements have documented that ozone photolysis can produce excited O2 in states as high as v"26. It has been suggested that these excited oxygen molecules can significantly influence the ozone budget in the upper atmosphere. For example, the stratospheric ozone concentration would be increased by 10% if only 10-4 of the total ozone photolysis leads to excited O2(v"26). Thus, mechanisms involving vibrationally excited oxygen molecules may be the missing source of ozone that is required in order to explain the inability of the atmospheric models to reproduce the actual vertical profile of stratospheric ozone. This research will investigate if the following mechanism provides an important source of stratospheric ozone: (1) O3 + hv (238 nm) O2(v"26) + O(3P) (2) O2(v"26) + O2 O3 + O (3) O + O2 + M O3 + M NET O3 + O2 O3 + O The reaction rates for step 2 in the preceding mechanism will be determined during this study with the cavity ring down absorption spectroscopic method. Temperature dependence measurements will also be performed. In addition, a direct measurement of the vibrational distribution from ozone photodissociation at 226 nm will be attempted for comparison with recent results reported by other workers. If these O2 photolysis products are vibrationally excited, then this will establish the atmospheric source of highly vibrationally excited O2 and its role in the ozone budget of the upper atmosphere.