Observation of Accurate Ion Dissociation Thresholds in Pulsed Field Ionization-Photoelectron Studies

Karl-Michael Weitzel; G. K. Jarvis; Marcus Malow; Tomas Baer; Y. Song; C. Y. Ng

doi:10.1103/PhysRevLett.86.3526

Observation of Accurate Ion Dissociation Thresholds in Pulsed Field Ionization-Photoelectron Studies

Karl-Michael Weitzel, G. K. Jarvis, Marcus Malow, Tomas Baer, Y. Song, and C. Y. Ng

Phys. Rev. Lett. 86, 3526 – Published 16 April 2001

Abstract

We report the first observation, together with a mechanism for such an observation, of a steplike feature in the pulsed field ionization photoelectron measurement of $CH_{4} (C_{2} H_{2})$ , marking the 0 K dissociation threshold for the formation of $CH_{3}^{+} + H (C_{2} H^{+} + H)$ from $CH_{4} (C_{2} H_{2})$ . The nonexistence of a step in the spectrum for $C_{2} H_{4}$ at its dissociation threshold for $C_{2} H_{2}^{+}$ formation provides strong support for the proposed mechanism. This experiment shows that, for a range of molecules, where the ion dissociation lifetimes near the dissociation thresholds are $< 10^{- 7} s$ , pulsed field ionization photoelectron measurements will yield not only highly accurate ionization energies, but also 0 K dissociation thresholds.

Received 12 October 2000

DOI:https://doi.org/10.1103/PhysRevLett.86.3526

Authors & Affiliations

Karl-Michael Weitzel¹, G. K. Jarvis², Marcus Malow¹, Tomas Baer³, Y. Song⁴, and C. Y. Ng^4,*

¹Freie Universität Berlin Institut für Chemie, Physikalische und Theoretische Chemie, Takustrasse 3, 14195 Berlin, Germany
²Lawrence Berkeley National Laboratory Chemical Science Division, Berkeley, California 94720
³The University of North Carolina at Chapel Hill, Department of Chemistry, Chapel Hill, North Carolina 27599-3290
⁴Ames Laboratory, USDOE and Iowa State University, Department of Chemistry, Ames, Iowa 50011