Vacuum Ultraviolet (VUV) Pulsed Field Ionization−Photoelectron and VUV−IR Photoinduced Rydberg Ionization Study of trans-Dichloroethene

Abstract

The vacuum ultraviolet (VUV) pulsed field ionization−photoelectron (PFI−PE) spectrum for trans-dichloroethene (trans-ClCHCHCl) has been measured in the energy range 77 600−79 200 cm-1. On the basis of the spectral simulation of the origin VUV−PFI−PE vibrational band, we have determined the IE(trans-ClCHCHCl) to be 77 678.4 ± 2.0 cm-1 (9.630 97 ± 0.000 25 eV). The vibrational bands resolved in the VUV−PFI−PE spectrum of trans-ClCHCHCl are assigned on the basis of ab initio vibrational frequencies and calculated Franck−Condon factors for the ionization transitions, yielding eight vibrational frequencies ν1 + = 163 cm-1, ν3 + = 367 cm-1, ν4 + = 871 cm-1, ν5 + = 915 cm-1, ν6 + = 944 cm-1, ν8 + = 1235 cm-1, ν9 + = 1258 cm-1, ν10 + = 1452 cm-1. The distinct feature of the VUV−PFI−PE spectrum is the strong vibrational progression of the ν3 + (CCl stretching) mode of trans-ClCHCHCl+, which is consistent with the theoretical geometry calculation, predicting a significant change in the CCl bond distance upon photoionization of trans-ClCHCHCl. We have also determined the frequency (3068 cm-1) for the ν11 + (CH stretching) vibrational mode of trans-ClCHCHCl+ by employing the VUV−IR-photoinduced Rydberg ionization (VUV−IR−PIRI) method. The VUV−IR−PIRI spectra for trans-ClCHCHCl prepared in the effective principal quantum numbers, n* = 14 and 36, are found to be identical, supporting the previous conclusion that the Rydberg electron behaves as a spectator; i.e., the Rydberg electron orbital is conserved during the IR excitation of the ion core.

One-Photon Mass-Analyzed Threshold Ionization Spectroscopy (MATI) of trans-Dichloroethylene (trans-C2H2Cl2): Cation Structure Determination via Franck−Condon Fit

“…The ionization energies thus determined were 9.6306 ( 0.0006, 9.6305 ( 0.0006, and 9.6304 ( 0.0006 eV for C 2 H 2 35 Cl 2, C 2 H 2 35 Cl 37 Cl, and C 2 H 2 37 Cl 2 isotopomers, respectively. These are in excellent agreement with the PFI-PE result reported by Ng and co-workers 23 as compared in Table 3.…”

“…23 Some discrepancies were observed between the experimental intensity pattern and the Franck-Condon factors evaluated using the molecular parameters calculated at the CCSD(T) level. In this work, a higher quality vibrational spectrum has been obtained with one-photon MATI.…”

The photoionization dynamics of the three structural isomers of dichloroethene

“…Higher resolution, laser-induced pulsed field ionisation-photoelectron and massanalysed threshold ionisation spectra have been reported for the trans-1,2 isomer [15,16]. There have been no studies, however, which combine the measurement of both photoelectrons and photoions under coincidence conditions.…”

Infrared Spectra of Chlorinated Ethylene Cations: C2Cl4+, C2HCl3+, 1,1-C2H2Cl2+, and trans-C2H2Cl2+ in Solid Argon

“…1 The radical cations and anions are potential important species in the processes of degradation and oxidation of chlorinated ethylenes. 2,3 Numerous experimental [4][5][6][7][8][9][10][11][12][13][14][15][16] and theoretical [17][18][19] studies have been performed on the spectra, structures, and reactions of chlorinated ethylene cations. The ionization potentials of the C 2 Cl 4 , C 2 HCl 3 , 1,1-C 2 H 2 Cl 2 , trans-C 2 H 2 Cl 2 , cis-C 2 H 2 Cl 2 , and C 2 H 3 Cl were measured by earlier photoelectron spectroscopic studies.…”

“…[17][18][19] More recently, the chlorinated ethylenes C 2 HCl 3 and cis-and trans-C 2 H 2 Cl 2 have been studied by employing the vacuum ultraviolet-infrared-photoinduced Rydberg ionization (VUV-IR-PIRI) spectroscopy, vacuum ultraviolet-pulsed field ionization-photoelectron (VUV-PFI-PE) spectroscopy, and one-photon mass-analyzed threshold ionization spectroscopy. [8][9][10][11][12][13] More accurate ionization potentials of the chlorinated ethylene neutrals were measured, and the vibrational frequencies of the chlorinated ethylene cations were determined.…”