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Title: High-resolution pulsed field ionization photoelectron-photoion coincidence spectroscopy using synchrotron radiation

Abstract

We have developed a sensitive and generally applicable scheme for performing pulsed field ionization (PFI) photoelectron (PFI-PE)-photoion coincidence (PFI-PEPICO) spectroscopy using two-bunch and multibunch synchrotron radiation at the Advanced Light Source. We show that this technique provides an ion internal state (or energy) selection limited only by the PFI-PE measurement. Employing a shaped pulse for PFI and ion extraction, a resolution of 0.6 meV [full width at half maximum (FWHM)] is observed in the PFI-PEPICO bands for Ar{sup +}({sup 2}P{sub 3/2,1/2}). As demonstrated in the PFI-PEPICO study of the process, O{sub 2}+h{nu}{r_arrow}O{sub 2}{sup +}(b&hthinsp;{sup 4}{Sigma}{sub g}{sup {minus}},&hthinsp;v{sup +}=4,&hthinsp;N{sup +})+e{sup {minus}}{r_arrow}O{sup +}({sup 4}S)+O({sup 3}P)+e{sup {minus}}, the dissociation of O{sub 2}{sup +}(b&hthinsp;{sup 4}{Sigma}{sub g}{sup {minus}},&hthinsp;v{sup +}=4) in specific rotational N{sup +} levels can be examined. The simulation of the experimental breakdown diagram for this reaction supports the conclusion that the threshold for the formation of O{sup +}({sup 4}S)+O({sup 3}P) from O{sub 2}{sup +}(b&hthinsp;{sup 4}{Sigma}{sub g}{sup {minus}},&hthinsp;v{sup +}=4) lies at N{sup +}=9. We have also recorded the PFI-PEPICO time-of-flight (TOF) spectra of O{sup +} formed in the dissociation of O{sub 2}{sup +}(b&hthinsp;{sup 4}{Sigma}{sub g}{sup {minus}},&hthinsp;v{sup +}=4{endash}7). The simulation of these O{sup +} TOF spectra indicates that the PFI-PEPICO method is applicable for themore » determination of kinetic energy releases. Previous PFI-PE studies on O{sub 2} suggest that a high-{ital n} O{sub 2} Rydberg state [O{sub 2}{sup {asterisk}}(n)] with a dissociative ion core undergoes prompt dissociation to yield a high-n{sup {prime}} O-atom Rydberg state [O{sup {asterisk}}(n{sup {prime}})] [Evans {ital et al.}, J. Chem. Phys. {bold 110}, 315 (1999)]. The subsequent PFI of O{sup {asterisk}}(n{sup {prime}}) accounts for the formation of a PFI-PE and O{sup +}. Since the PFI-PE intensities for O{sup +} and O{sub 2}{sup +} depend on the lifetimes of O{sup {asterisk}}(n{sup {prime}}) and O{sub 2}{sup {asterisk}}(n), respectively, the PFI-PE intensity enhancement observed for rotational transitions to O{sub 2}{sup +}(b&hthinsp;{sup 4}{Sigma}{sub g}{sup {minus}},&hthinsp;v{sup +}=4,&hthinsp;N{sup +}{ge}9) can be attributed to the longer lifetimes for O{sup {asterisk}}(n{sup {prime}}) than those for O{sub 2}{sup {asterisk}}(n). The PFI-PEPICO study of the dissociation of CH{sub 3}{sup +} from CH{sub 4} also reveals the lifetime effects and dc field effects on the observed intensities for CH{sub 3}{sup +} and CH{sub 4}{sup +}. The high resolution for PFI-PEPICO measurements, along with the ability to distinguish the CH{sub 3}{sup +} fragments due to the supersonically cooled CH{sub 4} beam from those formed by the thermal CH{sub 4} sample, has allowed the determination of a highly accurate dissociation threshold for CH{sub 3}{sup +} from CH{sub 4}. {copyright} {ital 1999 American Institute of Physics.}« less

Authors:
 [1]; ;  [2];  [3]; ;  [4]
  1. Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
  2. Freie Universitaet Berlin, Institut fuer Physikalische und Theoretische Chemie, Takustrasse 3, D-14195 Berlin (Germany)
  3. Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290 (United States)
  4. Ames Laboratory, U.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States)
Publication Date:
OSTI Identifier:
692521
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 70; Journal Issue: 10; Other Information: PBD: Oct 1999
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; 44 INSTRUMENTATION, INCLUDING NUCLEAR AND PARTICLE DETECTORS; PHOTOELECTRON SPECTROSCOPY; PHOTOIONIZATION; SYNCHROTRON RADIATION; DESIGN; OPERATION

Citation Formats

Jarvis, G K, Weitzel, K, Malow, M, Baer, T, Song, Y, and Ng, C Y. High-resolution pulsed field ionization photoelectron-photoion coincidence spectroscopy using synchrotron radiation. United States: N. p., 1999. Web. doi:10.1063/1.1150009.
Jarvis, G K, Weitzel, K, Malow, M, Baer, T, Song, Y, & Ng, C Y. High-resolution pulsed field ionization photoelectron-photoion coincidence spectroscopy using synchrotron radiation. United States. https://doi.org/10.1063/1.1150009
Jarvis, G K, Weitzel, K, Malow, M, Baer, T, Song, Y, and Ng, C Y. Fri . "High-resolution pulsed field ionization photoelectron-photoion coincidence spectroscopy using synchrotron radiation". United States. https://doi.org/10.1063/1.1150009.
@article{osti_692521,
title = {High-resolution pulsed field ionization photoelectron-photoion coincidence spectroscopy using synchrotron radiation},
author = {Jarvis, G K and Weitzel, K and Malow, M and Baer, T and Song, Y and Ng, C Y},
abstractNote = {We have developed a sensitive and generally applicable scheme for performing pulsed field ionization (PFI) photoelectron (PFI-PE)-photoion coincidence (PFI-PEPICO) spectroscopy using two-bunch and multibunch synchrotron radiation at the Advanced Light Source. We show that this technique provides an ion internal state (or energy) selection limited only by the PFI-PE measurement. Employing a shaped pulse for PFI and ion extraction, a resolution of 0.6 meV [full width at half maximum (FWHM)] is observed in the PFI-PEPICO bands for Ar{sup +}({sup 2}P{sub 3/2,1/2}). As demonstrated in the PFI-PEPICO study of the process, O{sub 2}+h{nu}{r_arrow}O{sub 2}{sup +}(b&hthinsp;{sup 4}{Sigma}{sub g}{sup {minus}},&hthinsp;v{sup +}=4,&hthinsp;N{sup +})+e{sup {minus}}{r_arrow}O{sup +}({sup 4}S)+O({sup 3}P)+e{sup {minus}}, the dissociation of O{sub 2}{sup +}(b&hthinsp;{sup 4}{Sigma}{sub g}{sup {minus}},&hthinsp;v{sup +}=4) in specific rotational N{sup +} levels can be examined. The simulation of the experimental breakdown diagram for this reaction supports the conclusion that the threshold for the formation of O{sup +}({sup 4}S)+O({sup 3}P) from O{sub 2}{sup +}(b&hthinsp;{sup 4}{Sigma}{sub g}{sup {minus}},&hthinsp;v{sup +}=4) lies at N{sup +}=9. We have also recorded the PFI-PEPICO time-of-flight (TOF) spectra of O{sup +} formed in the dissociation of O{sub 2}{sup +}(b&hthinsp;{sup 4}{Sigma}{sub g}{sup {minus}},&hthinsp;v{sup +}=4{endash}7). The simulation of these O{sup +} TOF spectra indicates that the PFI-PEPICO method is applicable for the determination of kinetic energy releases. Previous PFI-PE studies on O{sub 2} suggest that a high-{ital n} O{sub 2} Rydberg state [O{sub 2}{sup {asterisk}}(n)] with a dissociative ion core undergoes prompt dissociation to yield a high-n{sup {prime}} O-atom Rydberg state [O{sup {asterisk}}(n{sup {prime}})] [Evans {ital et al.}, J. Chem. Phys. {bold 110}, 315 (1999)]. The subsequent PFI of O{sup {asterisk}}(n{sup {prime}}) accounts for the formation of a PFI-PE and O{sup +}. Since the PFI-PE intensities for O{sup +} and O{sub 2}{sup +} depend on the lifetimes of O{sup {asterisk}}(n{sup {prime}}) and O{sub 2}{sup {asterisk}}(n), respectively, the PFI-PE intensity enhancement observed for rotational transitions to O{sub 2}{sup +}(b&hthinsp;{sup 4}{Sigma}{sub g}{sup {minus}},&hthinsp;v{sup +}=4,&hthinsp;N{sup +}{ge}9) can be attributed to the longer lifetimes for O{sup {asterisk}}(n{sup {prime}}) than those for O{sub 2}{sup {asterisk}}(n). The PFI-PEPICO study of the dissociation of CH{sub 3}{sup +} from CH{sub 4} also reveals the lifetime effects and dc field effects on the observed intensities for CH{sub 3}{sup +} and CH{sub 4}{sup +}. The high resolution for PFI-PEPICO measurements, along with the ability to distinguish the CH{sub 3}{sup +} fragments due to the supersonically cooled CH{sub 4} beam from those formed by the thermal CH{sub 4} sample, has allowed the determination of a highly accurate dissociation threshold for CH{sub 3}{sup +} from CH{sub 4}. {copyright} {ital 1999 American Institute of Physics.}},
doi = {10.1063/1.1150009},
url = {https://www.osti.gov/biblio/692521}, journal = {Review of Scientific Instruments},
number = 10,
volume = 70,
place = {United States},
year = {1999},
month = {10}
}