Application of a multivariate normal distribution methodology to the dissociation of doubly ionized molecules: The DMDS (CH₃‐SS‐CH₃) case

Abstract

The use of a Multivariate Normal Distribution allows for the representation of the whole ion-ion mass spectrum of doubly or multiply ionized molecules as a combination of parameters and the extraction of information among overlapped data. We have successfully applied this methodology to the analysis of the fragmentation of the DMDS molecule. Copyright © 2015 John Wiley & Sons, Ltd.

Breaking the disulfide chemical bond using high energy photons: the dimethyl disulfide and methyl propyl disulfide molecules

“…higher relative intensities in the DMDS electron impact mass spectrum, obtained both at low impact energy (NIST MS Number 291515) and at high electron incident energy (800 eV). 37 They are also observed in lower energy photon induced mass spectra, as described below.…”

Are disulfide bonds resilient to double ionization? Insights from coincidence spectroscopy and ab initio calculations

“…Details of the experimental setup are also described elsewhere. 46,49 At high photon energy regimes, there is a large probability of double (or multiple) ionization, whose molecular states are usually highly dissociative. PEPIPICO experiments were employed to characterize the main ionic fragments from such events.…”

“…A complete description of the method can be found elsewhere. 46 Briey, the ion-ion coincidence spectrum is considered as a linear combination of Gaussian-type multivariate functions. The full width at half maximum (FWHM) for a Gaussian function is given by:…”

“…Single dissociation pathways of DMDS at lower energies were also studied by Butler et al 44 and Chiang et al 45 In a previous work, we investigated the ion-ion coincidence spectrum of DMDS obtained at an incident electron energy of 800 eV (valence-shell study due to the energy transferred aer the impact). 46 In this work, we extend this analysis to high-energy photon impact ($ 2400 eV). Photoelectron-photoion-photoion coincidence (PEPIPICO) experiments 47,48 were employed in order to investigate the most relevant mechanisms of ionic fragmentation aer double ionization starting from excitation around the S 1s edge.…”

“…For analyzing the PEPIPICO data, we applied a multivariate normal distribution methodology adapted by our group to study coincidence techniques. 46 Additionally, we apply quantum chemical calculations in order to elucidate the structure and relative stability of C 2 H 6 S 2 2+ isomers, aiming at investigating the stability of the disulde bond aer production of a doubly ionized dimethyl disulde. Density functional theory and coupled-cluster calculations were used for mapping the minimum energy geometries of the dicationic C 2 H 6 S 2…”