Laser excited metastable states of acetylene in the 5.5–5.7 eV region

Abstract

Experimental results are presented which show UV excitation to metastable states of C2H2 above and below the dissociation limit. A strong S1–T3 interaction, located close in energy to the S13ν3 (trans-bend) vibrational level is detected. A “gateway mediated intersystem crossing” singlet–triplet coupling mechanism explains the results.