15min:

NILS HANSEN AND ALEC M. WODTKE, Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106; ANATOLY V. KOMISSAROV AND MICHAEL C. HEAVEN, Department of Chemistry, Emory University, Atlanta, Georgia 30322.

The photoionization and fragmentation dynamics of ClN₃ have been examined using 203 nm excitation with (2+1) REMPI detection of the N₂ product. Kinetic energy and angular distributions of N₂ and NCl⁺ were characterized by velocity map imaging. \linebreak The N₂ product was formed with appreciable rotational excitation, with population in levels as high as J=90. Velocity map images for the J=50 fragment showed that the maximum energy released to translation was 1.14 eV. This result indicated that the N₂ did not come from the expected channel, ClN₃ +h NCl(a¹ ) + N₂, which would produce much more energetic fragments. Velocity maps of N₂ and NCl⁺ were consistent with the process \begincenter ClN₃ + 2h NCl⁺ + N₂
\endcenter The observed kinetic energy distributions of the N₂ and NCl⁺ photoproducts are consistent with the formation of vibrationally excited NCl⁺. The velocity maps of photoelectrons peaked near zero velocity, showing that ClN₃⁺ is formed with nearly all excess energy in vibration. Ab initio calculations (CCSD(T)/cc-pVTZ) confirm that ClN₃⁺ is unstable with respect to decomposition to NCl⁺ and N₂. In combination, the experimental and theoretical results can be used to obtain the thermodynamics of the ClN₃ +h NCl(a¹ ) + N₂ reaction. The fact that products correlating with NCl(a) could not be observed suggests that the state of ClN₃ accessed by 203 nm excitation does not undergo direct dissociation.