Cluster Model Studies of Anion and Molecular Specificities via Electrospray Ionization Photoelectron Spectroscopy

Abstract

Ion specificity, a widely observed macroscopic phenomenon in condensed phases and at interfaces, is a fundamental chemical physics issue. Herein we report our recent studies of such effects using cluster models in an "atom-by-atom" and "molecule-by-molecule" fashion not possible with the condensed-phase methods. We use electrospray ionization (ESI) to generate molecular and ionic clusters to simulate key molecular entities involved in local binding regions and characterize them by employing negative ion photoelectron spectroscopy (NIPES). Inter- and intramolecular interactions and binding configurations are directly obtained as functions of the cluster size and composition, providing molecular-level descriptions and characterization over the local active sites that play crucial roles in determining the solution chemistry and condensed-phase phenomena. The topics covered in this article are relevant to a wide range of research fields from ion specific effects in electrolyte solutions, ion selectivity/recognition in normal functioning of life, to molecular specificity in aerosol particle formation, as well as in rational material design and synthesis.

Photoelectron spectroscopy of isolated luciferin and infraluciferin anions in vacuo: competing photodetachment, photofragmentation and internal conversion

“…29,30 Photoelectron spectra were recorded using our anion photoelectron imaging spectrometer which combines an electrospray anion source with collinear velocity-map imaging detection of electrons. The electrospray anion photodetachment spectroscopy method was pioneered by LS Wang 31 and used by XB Wang 32 and photoelectron imaging spectroscopy of anions is employed by a number of groups [33][34][35][36][37] as well as our own. [38][39][40][41][42][43][44][45] The design of our spectrometer is described in an earlier publication.…”

Dynamics of π*-resonances in anionic clusters of para-toluquinone

“…14,[40][41][42][43] The present study provides an intriguing example of highly specific cluster/microsolvation excited state dynamics for sizeselected pTQ cluster anions. While the frequency-resolved spectra show evidence of monomer-like dynamics for (pTQ) 3 -, strong interaction between the charged monomer and neighbouring neutral monomers leads to new decay channels.…”

“…[15][16][17] It is therefore desirable to start with simple prototypes and characterise trends with increasing coordination in a bottom-up approach. 14,18 Here, we present a frequency-resolved photoelectron spectroscopy study of monomer, dimer, and trimer radical anions of para-toluquinone (methyl-para-benzoquinone, pTQ). The minimum energy structures of these species are shown in Fig.…”

Macrocycle‐Directed Construction of Tetrahedral Anion–π Receptors for Nesting Anions with Complementary Geometry

“…The binding strength for the anion complexes was further measured by negative ion photoelectron spectroscopy (NIPES) study . In this technique, the difference of electron binding energy (EBE) of an anion complex and EBE of the sole anion, that is, ΔEBE, can be a good estimation for direct anion binding strength (see Supporting Information for details) .…”

“…The binding strengthf or the anion complexes was further measured by negative ion photoelectron spectroscopy (NIPES) study. [16] In this technique, the difference of electron binding energy (EBE) of an anion complex and EBEo ft he sole anion, that is, DEBE, can be ag ood estimation for direct anion binding strength (see SupportingI nformation for details). [17,18] The 10 KN IPE spectra of the complexes T1·SO 4 2À , T1·HSO 4 À and T1·ClO 4 À were obtained at 157 and 266 nm ( Figure 6; the EBE values of BF 4 À and PF 6 À are too high to be measured with a 157-nm laser,w hich is the highest photon-energy laser available in the lab).…”