PNNL

Abstract

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The infrared (IR)-vacuum ultraviolet (VUV)-pulsed field ionization-photoelectron (IR-VUV-PFI-PE) spectrum for C2H4(X÷ 1Ag, V11 = 1, N'Ka'Kc'=303) in the VUV range of 83 000-84 800 cm-1 obtained using a single mode infrared laser revealed 24 rotationally resolved vibrational bands for the ion C2H4 +(X÷ 2B3u) ground state. The frequencies and symmetry of the vibrational bands thus determined, together with the anharmonic frequency predictions calculated at the CCSD(T)/aug-cc-pVQZ level, have allowed the unambiguous assignment of these vibrational bands. These bands are mostly combination bands. The measured frequencies of these bands yield the fundamental frequencies for V8 + ) 1103 ( 10 cm-1 and V10 + ) 813 ( 10 cm-1 of C2H4 +(X÷ 2B3u), which have not been determined previously. The present IR-VUV-PFI-PE study also provides truly rovibrationally selected and resolved state-to-state cross sections for the photoionization transitions C2H4(X~1Ag; V11, N'Ka'Kc') ? C2H4 +(X~ 2B3u; Vi +, N+ Ka +Kc +), where N'Ka'Kc' denotes the rotational level of C2H4(X~ 1Ag; V11), and Vi + and N+ Ka +Kc + represent the vibrational and rotational states of the cation.