Eur. Phys. J. D 43, 23-26 (2007)
https://doi.org/10.1140/epjd/e2007-00061-5

Photodissociation spectroscopy of the chromium trimer ion

¹ East Tokyo Laboratory, Genesis Research Institute, Inc., 717-86 Futamata, Ichikawa, Chiba, 272-0001, Japan
² Cluster Research Laboratory, Toyota Technological Institute, in East Tokyo Laboratory, Genesis Research Institute, Inc., 717-86 Futamata, Ichikawa, Chiba, 272-0001, Japan
³ Institute for Materials Research, Tohoku University, Sendai, 980-77, Japan

Corresponding author: ^a kondow@clusterlab.jp

Received: 23 July 2006
Revised: 15 November 2006
Published online: 24 May 2007

Abstract

The electronic and geometric structures and photodissociation dynamics of the chromium trimer ion, Cr₃⁺, were investigated by photodissociation spectroscopy in the photon-energy range from 1.32 to 5.52 eV. The branching fractions of the product ions, Cr⁺ and Cr₂⁺, exhibit stepwise changes at the threshold energies for dissociation into Cr⁺+Cr₂, Cr+Cr₂⁺, Cr⁺+2Cr, and Cr^*+Cr₂⁺. It is noted that Cr₂⁺ is produced even above the threshold for atomization; the excess energy is redistributed to produce a fragment atom, Cr^*, in an excited state. The photodissociation action spectrum is well explained by a mixture of simulated spectra for two nearly-degenerate structural isomers identified by density functional calculations: those having a metastable C_2v structure and the most stable structure slightly distorted from the C_2v one. The barrier height between the two isomers which is lower than the zero-point energy suggests that Cr₃⁺ has an intrinsically floppy structure.