We report experimental vibrational spectra of thermalized carbon disulfide dimer anions, (CS2)2-, measured at ion trap temperatures from 16 to 300 K. Previous experiments showed evidence for several (CS2)2- isomers, whose relative abundance depends on the source conditions. We used infrared (IR) photodissociation spectroscopy in the fingerprint region (550-1600 cm-1) of (CS 2)2- thermalized in a temperature-controllable ion trap, in combination with simulated IR spectra derived from ab initio calculations, to identify the isomers present at various ion trap temperatures. The IR photodissociation spectra show characteristic signatures for at least three different isomers. Anions formed in the source are primarily trapped as high-energy ion-molecule complexes, in which the unpaired electron is localized on a single CS2 moiety. Thermal heating supplies sufficient energy to overcome the isomerization barriers and shifts the isomer population via a weakly bound isomer, in which the electron is delocalized over the complete complex, to lower-energy covalently bound structures.
ASJC Scopus subject areas
- Materials Science(all)
- Physical and Theoretical Chemistry