Observation of collisional ionization electron spectra of van der Waals clusters with metastable He*(2 3 S) atoms: An evidence for autoionization from superexcited Ar clusters

Hideyasu Tanaka, Ryo Maruyama, Yoshihiro Yamakita, Hideo Yamakado, Fuminori Misaizu, Koichi Ohno

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Penning ionization electron spectra (PIES) of van der Waals clusters have been observed for the first time by means of a newly developed magnetic bottle electron spectrometer, which is 1000 times more efficient than a conventional PIES apparatus. In the PIES of Ar clusters with He*(2 3S), two bands of Ar 3p hole characters with different ionization energies (IE), band A (IE=ca.15 eV) and band B (IE=ca.13.5 eV), were observed. Band A was assigned to vertical transitions in Franck-Condon regions corresponding to the band in the ultraviolet photoelectron spectra (UPS) of clusters reported by Carnovale et al. [J. Chem. Phys. 90, 1452 (1989)]. Band B, which is an extra band missing in the UPS of clusters, can be ascribed to the autoionization into a stable structure of Ar+n via superexcited states of Arn. Band B can be considered as an adiabatic ionization which is forbidden as a direct ionization. The energy difference of ca. 1.5 eV between the vertical IE for band A and the adiabatic IE for band B was found to agree well with the reported binding energy of the trimer ion core.

Original languageEnglish
Pages (from-to)7062-7067
Number of pages6
JournalJournal of Chemical Physics
Volume112
Issue number16
DOIs
Publication statusPublished - 2000 Apr 22

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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