Rotationally resolved pulsed field ionization photoelectron bands of O[sub 2][sup +](X [sup 2][Pi][sub 1/2,3/2g],v[sup +]=0[endash]38) in the energy range of 12. 05[endash]18. 15 eV
- Ames Laboratory, U.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States)
- Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
We have obtained rotationally resolved pulsed field ionization photoelectron (PFI-PE) spectra for O[sub 2] in the energy range of 12.05[endash]18.15 eV, covering ionization transitions O[sub 2][sup +](X hthinsp;[sup 2][Pi][sub 1/2,3/2g], hthinsp;v[sup +]=0[endash]38,J[sup +])[l arrow]O[sub 2](X hthinsp;[sup 3][Sigma][sub g][sup [minus]], hthinsp;v[sup +]=0,N[sup [double prime]]). While the PFI-PE bands for O[sub 2][sup +](X hthinsp;[sup 2][Pi][sub 1/2,3/2g], v[sup +]=3[endash]5, 9, 11, 12, 22, and 25[endash]38) reported here are the first rotational-resolved photoelectron measurements, the PFI-PE bands for O[sub 2][sup +](X hthinsp;[sup 2][Pi][sub 1/2,3/2g], hthinsp;v[sup +]=25[endash]38) represent the first rotationally resolved spectroscopic data for these states. The simulation of spectra obtained at rotational temperatures of [approx]20 and 220 K allows the unambiguous identification of O[sub 2][sup +](X hthinsp;[sup 2][Pi][sub 1/2,3/2g], hthinsp;v[sup +][ge]21) PFI-PE bands, the majority of which overlap with prominent PFI-PE bands for O[sub 2][sup +](A hthinsp;[sup 2][Pi][sub u], hthinsp;v[sup +]=0[endash]12) and O[sub 2][sup +](a hthinsp;[sup 4][Pi][sub u], hthinsp;v[sup +]=0[endash]18). Combined with spectroscopic data obtained in the previous emission study and the present PFI-PE experiment, we have obtained accurate Dunham-type expansion coefficients for ionization energies, vibrational constants, rotational constants, and spin[endash]orbit splitting constants covering the O[sub 2][sup +](X hthinsp;[sup 2][Pi][sub 1/2,3/2g], hthinsp;v[sup +]=0[endash]38) states. Significant local intensity enhancements due to near-resonant autoionization were observed in PFI-PE bands for O[sub 2][sup +](X hthinsp;[sup 2][Pi][sub 1/2,3/2g], hthinsp;v[sup +]=0[endash]14). The energy region of these states is known to manifest a high density of very strong autoionizing low-[ital n]-Rydberg states. The observation of a long PFI-PE vibrational progression with a relatively smooth band intensity profile is also in accord with the direct excitation model for the production of highly vibrationally excited O[sub 2][sup +](X hthinsp;[sup 2][Pi][sub 1/2,3/2g]) states in the Franck[endash]Condon gap region. Since this experiment was carried out under relatively high rotational temperatures for O[sub 2], the PFI-PE data reveal higher rotational transitions and numerous local intensity enhancements, which were not observed in previous vacuum ultraviolet laser studies using a cold O[sub 2] molecular beam. The rotational branches found here indicate that photoelectrons are formed predominantly in continuum states with orbital angular momenta l=1,3, and 5. [copyright] [ital 1999 American Institute of Physics.]
- OSTI ID:
- 6270751
- Journal Information:
- Journal of Chemical Physics, Vol. 111:5; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
Similar Records
Rotationally resolved pulsed field ionization photoelectron study of CO[sup +](X[sup 2][Sigma][sup +],v[sup +]=0[endash]42) in the energy range of 13. 98[endash]21. 92 eV
Rotationally resolved pulsed field ionization photoelectron study of CO{sup +}(X{sup 2}{Sigma}{sup +},v{sup +}=0{endash}42) in the energy range of 13.98{endash}21.92 eV
Related Subjects
AUTOIONIZATION
CATIONS
ENERGY-LEVEL TRANSITIONS
EV RANGE 10-100
EXCITED STATES
FRANCK-CONDON PRINCIPLE
MOLECULAR IONS
OXYGEN
OXYGEN IONS
PHOTOELECTRON SPECTROSCOPY
ROTATIONAL STATES
VIBRATIONAL STATES
CHARGED PARTICLES
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY LEVELS
ENERGY RANGE
EV RANGE
IONIZATION
IONS
NONMETALS
SPECTROSCOPY
664200* - Spectra of Atoms & Molecules & their Interactions with Photons- (1992-)