Identification of New {CIS} Vibrational Levels in the S1 State of C2H2 Conference Paper uri icon


  • Abstract Although the S_1 (tilde {A}^ 1A_u) state of the trans conformer of acetylene has been known for many years, the corresponding S_1 (tilde {A}^ 1A_2) state of the cis conformer was only discovered recently. Transitions to it from the ground state are electronically forbidden, but its vibrational levels acquire intensity by tunneling through the isomerization barrier and interacting with levels of the trans conformer. We have recently identified two new vibrational levels (3 2 and 4 1 6 1) of the {cis} conformer of S 1 C 2 H 2, bringing the total number of levels observed to six out of an expected ten up to the energies studied in this work. The appearance of these levels in IR-UV double resonance LIF spectra will be discussed, along with their vibrational assignments. Experimentally determined vibrational parameters and {ab initio} anharmonic force fields for both the {trans} and {cis} …

publication date

  • June 1, 2012