33.14-P

Spectroscopic Identification of the Primary Products of Metastable Diacetylene Photochemistry.

C. Ramos, C.A. Arrington, A.D. Robinson, T.S. Zwier (Purdue University)

The ultraviolet photochemical reactions of diacetylene are thought to provide some of the precursor material for the visible absorbing haze which envelops Titan. Our group has studied the ultraviolet photo- chemistry of metastable diacetylene (C H ) with a series of hydrocarbons important to the atmosphere of Titan. The aim of these experiments was to determine the primary reaction products. Initially these primary products were identified only by mass spectroscopy. The addition of a tunable light source to our experimental setup has allowed the spectroscopic identification of the primary products of these reactions via resonant two photon ionization (R2PI) and ionization potential measurements. In this poster we present spectra which unambiguously identify these primary products.

One of the most interesting results is the identification of benzene and phenylacetylene as the primary products of the butadiene plus C H reaction. The primary products of the self reaction C H + C H and propene + C H , are C H and C H , respectively. These hydrocarbons have been identified as triacetylene and hex-1-ene-3,5-diyne by R2PI spectroscopy. Ionization potentials of C H and C H , the primary products of the C H + C H reaction, have been measured and agree with literature values for triacetylene and tetraacetylene. These product structures are consistent with earlier mechanistic predictions.