skip to main content

Title: Field ionization of high-Rydberg fragments produced after inner-shell photoexcitation and photoionization of the methane molecule

We have studied the production of neutral high-Rydberg (HR) fragments from the CH{sub 4} molecule at the C 1s → 3p excitation and at the C 1s ionization threshold. Neutral fragments in HR states were ionized using a pulsed electric field and the resulting ions were mass-analyzed using an ion time-of-flight spectrometer. The atomic fragments C(HR) and H(HR) dominated the spectra, but molecular fragments CH{sub x}(HR), x = 1-3, and H{sub 2}(HR) were also observed. The production of HR fragments is attributed to dissociation of CH{sub 4}{sup +} and CH{sub 4}{sup 2+} ions in HR states. Just above the C 1s ionization threshold, such molecular ionic states are created when the C 1s photoelectron is recaptured after single or double Auger decay. Similar HR states may be reached directly following resonant Auger decay at the C 1s → 3p resonance. The energies and geometries of the parent and fragment ions have been calculated in order to gain insight into relevant dissociation pathways.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Consiglio Nazionale delle Ricerche–Istituto Officina dei Materiali, Laboratorio TASC, 34149 Trieste (Italy)
  2. Department of Physics, Lund University, P.O. Box 118, 22100 Lund (Sweden)
  3. Department of Physics, University of Oulu, P.O. Box 3000, 90014 Oulu (Finland)
  4. MAX IV Laboratory, Lund University, P.O. Box 118, 22100 Lund (Sweden)
  5. Colegio Los Naranjos, Fuenlabrada, 28941 Madrid (Spain)
  6. Elettra-Sincrotrone Trieste, Area Science Park Basovizza, 34149 Trieste (Italy)
Publication Date:
OSTI Identifier:
22489604
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 11; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DISSOCIATION; ELECTRIC FIELDS; EXCITATION; IONS; METHANE; MOLECULES; PHOTOIONIZATION; PULSES; RESONANCE; SPECTRA; TIME-OF-FLIGHT SPECTROMETERS