15min:

SHARON C. KETTWICH AND DAVID T. ANDERSON, Department of Chemistry, University of Wyoming, Laramie, WY 82071-3838, USA; PAUL L. RASTON, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.

Matrix isolation spectroscopy is a technique which enables highly reactive species to be trapped in a host environment and studied spectroscopically. Solid parahydrogen (pH₂) has been employed as a matrix host because of its interesting quantum mechanical properties and also because of its general inertness towards trapped dopants. However, in some cases pH₂ can react with impurities yielding new product molecules and providing insight into non-classical reaction pathways. In this talk I will present the results from a series of experiments where molecular chlorine (Cl₂) doped pH₂ crystals were exposed to two different irradiation schemes (namely UV only or IR + UV conditions) that gave rise to very different products. Cl₂ doped pH₂ crystals irradiated with 355\: \:nm UV light produced almost exclusively (99%) isolated Cl-atom photofragments, indicating the reaction Cl+H₂( =0, J=0) HCl+H is not readily occurring. Cl₂ doped pH₂ exposed simultaneously to 355\: \:nm UV irradiation and broadband cw\: IR light yielded HCl photoproducts indicating that the following reaction is playing a significant (15%) role in the in situ photochemistry: Cl+H₂( =1, J=0) HCl+H. The kinetic analysis of these experiments with two very different reaction pathways for UV only or IR + UV conditions will be presented. Further, the results of current investigations involving spin-orbit excited Cl-atoms generated using 416\: \:nm\: \:UV photons will be discussed in order to explore the intriguing possibility of non-Born Oppenheimer reaction dynamics in the simple Cl+H₂ reaction.