How generic is iodide-tagging photoelectron spectroscopy: An extended investigation on the Gly·X- (Gly = glycine, X = Cl or Br) complexes

Wenjin Cao; Qinqin Yuan; Hanhui Zhang; Xiaoguo Zhou; Steven R Kass; Xue-Bin Wang

doi:10.1063/5.0159326

How generic is iodide-tagging photoelectron spectroscopy: An extended investigation on the Gly·X- (Gly = glycine, X = Cl or Br) complexes

J Chem Phys. 2023 Jul 21;159(3):034305. doi: 10.1063/5.0159326.

Authors

Wenjin Cao¹, Qinqin Yuan^{1

2}, Hanhui Zhang^{1

3}, Xiaoguo Zhou³, Steven R Kass⁴, Xue-Bin Wang¹

Affiliations

¹ Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
² Key Laboratory of Structure and Functional Regulation of Hybrid Materials (Ministry of Education), Department of Chemistry, Anhui University, Hefei 230601, China.
³ Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
⁴ Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA.

PMID: 37466228
DOI: 10.1063/5.0159326

Abstract

We report a joint negative ion photoelectron spectroscopy (NIPES) and quantum chemical computational study on glycine-chloride/bromide complexes (denoted Gly·X-, X = Cl/Br) in close comparison to the previously studied Gly·I- cluster ion. Combining experimental NIPE spectra and theoretical calculations, various Gly·X- complexes were found to adopt the same types of low-lying isomers, albeit with different relative energies. Despite more congested spectral profiles for Gly·Cl- and Gly·Br-, spectral assignments were accomplished with the guidance of the knowledge learned from Gly·I-, where a larger spin-orbit splitting of iodine afforded well-resolved, recognizable spectral peaks. Three canonical plus one zwitterionic isomer for Gly·Cl- and four canonical conformers for Gly·Br- were experimentally identified and characterized in contrast to the five canonical ones observed for Gly·I- under similar experimental conditions. Taken together, this study investigates both genericity and variations in binding patterns for the complexes composed of glycine and various halides, demonstrating that iodide-tagging is an effective spectroscopic means to unravel diverse ion-molecule binding motifs for cluster anions with congested spectral bands by substituting the respective ion with iodide.