Multipathway dissociation dynamics of core-excited methyl chloride probed by high resolution electron spectroscopy and Auger-electron–ion coincidences

Abstract

Core excitation triggers nuclear dynamics on the femtosecond time scale. A multiparametric electron/ion coincidence approach has been used to disentangle complex decay processes occurring at short (molecular) or long (atomic) time scales. Methyl chloride has been excited by scanning along the dissociative Cl2p-->sigma* resonance. The detailed chronology of the competing decay processes, leading to either the rearrangement product HCl(+), or an ultrafast dissociation leading to Cl(+), has been investigated. The observed Auger-Doppler shift has been analyzed for various orientations of the electron and fragment ion.

Role of ultrafast dissociation in the fragmentation of chlorinated methanes

“…In the creation of HCl + though, there is an additional hydrogen movement from the methyl group towards the chlorine atom. The appearance of HCl + subsequent to the Auger decay in CH 3 Cl has been investigated before, and has been attributed to a specific rotation of the methyl group that occurs in one of the Auger final states 17,33 .…”

“…⇤ excitation 10,33,50,51 . The dissociation process has been explained to happen while the molecule is still in the core-excited state.…”

“…All created positive ions were subsequently detected. Fragmentation of CH 3 Cl and CH 2 Cl 2 has been studied by Miron et al 33 and recently by Alcantara et al 25 , respectively, using similar methods. We complement these works with a systematic study of these four molecules under similar experimental conditions.…”

High‐resolution Inner‐shell Photoionization, Photoelectron and Coincidence Spectroscopy

“…By such coincidence measurements, it is possible, for instance, to obtain the resonant Auger decay spectra associated with a given fragment ion production: mass-selected photoelectron spectra (MSPES) (see Miron et al (2008) for more details). Figure 28 shows the MSPES spectra obtained for the excitation on top of the Cl 2p → σ * resonance.…”

Development and characterization of a multiple-coincidence ion-momentum imaging spectrometer

“…[1][2][3][4][5] Synchrotron radiation is a unique light source providing the ability to selectively ionize particular electronic shells, excite localized core-electronic states, and to select the polarisation of the light. In this context, spectroscopic imaging instruments of various designs [6][7][8][9][10] allow recording the velocity or momenta of several reaction products in coincidence with energy-analyzed electrons to reveal the details of dissociative states in molecules.…”