Fragmentation of methyl chloride studied by partial positive and negative ion-yield spectroscopy

Abstract

The authors present partial-ion-yield experiments on the methyl chloride molecule excited in the vicinity of the Cl2p and C1s inner shells. A large number of fragments, cations produced by dissociation or recombination processes, as well as anionic species, have been detected. Although the spectra exhibit different intensity distributions depending on the core-excited atom, general observations include strong site-selective fragmentation along the C-Cl bond axis and a strong intensity dependence of transitions involving Rydberg series on fragment size.

Photofragmentation of cyanogen upon carbon and nitrogen K-shell excitation by partial ion yield experiments

“…The general appearance of the partial yield spectra in the energy region below threshold is quite similar, but there are some significant differences which can aid in achieving a detailed spectral assignment. By comparing the partial yields shown in Fig.2, we notice an effect we have reported for several other systems [27,28], and namely that the relative intensity of the Rydberg series is higher for the smaller fragments. This is due to the fact that the excitations to Rydberg states decay mainly through spectator processes, and therefore the final states are mostly dissociative in nature.…”

“…Formation of N + 2 requires a strong rearrangement of the molecular structure as it involves the breaking of two triple bonds between the nitrogen and the carbon atoms and the formation of a new bond between the two nitrogen atoms. Other examples of intramolecular atomic rearrangement were previously observed, involving the breaking of a H-X bond and formation of another bond during the reconfiguration of the electronic structure of the molecule following photoionization: formation of H [28]. In both of these examples, rearrangement is possible due to the high mobility of protons and is aided by vibrational excitation.…”

“…This finding was explained on the ground of the transitions to Rydberg states leading mainly to spectator decay, therefore to final states often dissociative in nature (see e.g. [27,28]). By using the method described above, we could identify several above-threshold features in (CN) 2 as either shape resonances or doubly excited states.…”

Resonant inelastic x-ray scattering of methyl chloride at the chlorine K edge

“…Mass spectra recorded with respect to the incident polarization vector were used to confirm the symmetry of the 8a 1 antibonding LUMO. Several other studies have shown [8][9][10] fast fragmentation of the molecule after core excitation near the Cl L 2, 3 edge, leading to the formation of either Cl + or HCl + . The Auger-Doppler shift also has been observed for various orientations of the electron and fragment ion.…”

“…9 Partial-ion-yield experiments on CH 3 Cl excited in the vicinity of the Cl 2p inner shell have shown site-selective fragmentation along the C-Cl bond axis and strong intensity dependence of Rydberg transitions on fragment size. 7,10 Resonant inelastic x-ray scattering (RIXS), on the other hand, is a powerful tool for elucidating the electronic properties of gas-phase molecules. The physical process underlying RIXS corresponds to resonant excitation of an inner-shell electron followed by relaxation of the core-hole via radiative decay, i.e., x-ray photon emission.…”