15min:

DAVID T. ANDERSON AND FREDRICK M. MUTUNGA, Department of Chemistry, University of Wyoming, Laramie, WY 82071-3838.

We report on the results of chemical reactions of H-atoms with N₂O in solid parahydrogen matrices investigated by rapid scan FTIR. The reaction is initiated by the 193 nm in situ photodissociation of N₂O to produce N₂ + O(¹D). We assume the O(¹D) photoproduct reacts with the parahydrogen host to create H-atoms. What we observe is growth of cis-HNNO right after photolysis is stopped along with a later delayed growth in trans-HNNO. We assign our peaks by comparison with a previous Xe matrix isolation study and recent ab initio calculations of the anharmonic vibrational frequencies and isotopic shifts. We performed some experiments using the ¹⁵N₂ ¹⁸O precursor molecule. Detailed study of the reaction kinetics indicate that at 1.8 K the cis-isomer is formed exclusively by the reaction, but then converts to the lower energy trans-isomer with time. These results are surprising because a 40 kJ/mol barrier is predicted for the H + N₂O reaction, yet the reaction readily proceeds even at 1.8 K. We are currently studying this reaction under a variety of conditions and the most current results and analysis will be presented.