The main beam correction term in kinetic energy release from metastable peaks

Abstract

The correction term for the precursor ion signal width in determination of kinetic energy release is reviewed, and the correction term is formally derived. The derived correction term differs from the traditionally applied term. An experimental finding substantiates the inaccuracy in the latter. The application of the "T-value" to study kinetic energy release is found preferable to kinetic energy release distributions when the metastable peaks are slim and simple Gaussians. For electronically predissociated systems, a "borderline zero" kinetic energy release can be directly interpreted in reaction dynamics with strong curvature in the reaction coordinate.

Electronic Predissociation in the Dichloromethane Cation CH2Cl2+ Electronic State 2A1

“…The experimental result processing methods have been thoroughly described in detail elsewhere. , The computational methods are outlined in section .…”

“…Previously 5 we reported a factor 9 heavyatom 1°kinetic isotope effect (KIE) in the loss of a chlorine atom from CH 2 35 Cl 37 Cl + , a very low KER, and a massive H/D 2°KIE. In a recent publication, 6 applying a revised main beam correction term, we reported the KER for the loss of Cl from CH 2 35 Cl 2 + to be 30 μeV or borderline zero, presumably the lowest KER ever reported from a MIKE experiment. Other sources report KERs of 10−15 meV, 17−19 but these values are most likely incorrect due to an unrecognized contribution from CID. In our first report, 5 we also concluded that no metastable reaction was detectable for CD 2 Cl 2 + .…”

“…4 The present study investigates the process by which ionized CH 2 Cl 2 dissociates according to the reaction CH 2 Cl 2 + → CH 2 Cl + + Cl as observed in the mass-analyzed ion kinetic energy (MIKE) experiment in continuation of previous investigations. 5,6 The findings here include very low kinetic energy release (KER) and high sensitivity toward collisionally induced decomposition (CID). Similar findings have been reported in systems where electronic predissociation 7−13 is involved.…”