15min:

CHRISTOPHER RAMOS, J. CARNEY, C. J. GRUENLOH AND T. S. ZWIER, Department of Chemistry, Purdue University, Lafayette, IN 47906 .

The chemical reactions of the long-lived triplet states of diacetylene (C₄H₂^*) with small hydrocarbons lead to a rich variety of poly-yne, ene-yne, and aromatic products. Characterization of these products is complicated by the number of isomers of some products which could be present. Resonant two-photon ionization (R2PI) has recently provided one level of spectroscopic characterization, but even here, the similarity of the electronic structures of the isomers can make positive identification difficult. In this talk, we report a first use of resonant ion-dip infrared spectroscopy (RIDIRS) to characterize two key products of C₄H₂^* reactions: the C₆H₂ product from C₄H₂^* + C₂H₂,C₄H₂, C₃H₄ and (ii) the C₆H₄ product from C₄H₂^* + C₂H₄, C₃H₆. The RIDIR spectra of these products is recorded in the CH stretch region. Characteristic absorptions due to acetylene CH stretch, ethylenic (=CH₂), and vinylic (=CHR) are identified. Partially-resolved rotational structure is also evident in the spectra.