ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
In (3+1) resonance enhanced multiphoton ionization photoelectron spectra (REMPI-PES) of CO2, photoionization competes with dissociation. In addition to direct photoionization, autoionization is possible through accidental resonances embedded in the continuum at the four-photon level. Photoabsorption from these long-lived autoionizing states leads to resonance enhanced above threshold absorption (REATA). REATA produces photoelectron terminations on the C˜ state of CO2+. Previous experiments did not indicate whether the dissociation occurred at the three-photon level or four-photon level. REMPI-PES of CO2 via several Rydberg states have been collected at a number of laser intensities, and it was found that the photoelectron spectra terminating on each individual ionic state do not change over the range of experimentally available laser intensities. This indicates that the dissociation of CO2 occurs at the four-photon level. The long vibrational progressions in the PES indicate that the dominant ionization process is autoionization rather than direct ionization. Relative intensities of the X˜ and C˜ state components of the PES do change with intensity, confirming the C˜ state assignment and its five-photon mechanism.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.464215
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