Molecular ionization of chloromethane in strong fields: nearest neighbor gateway to highly charged ions

Abstract

The strong and ultrastrong field-molecule interaction is a complex, many-body process involving multiple ionization processes. We present ion yields and molecular fragment energies for the ionization of chloromethane (CH 3 Cl) in a laser field with intensities spanning from 10 14 to 10 17 W cm −2 . As the laser intensity increases, ionization of CH 3 Cl is observed to pass from molecular tunneling, to enhanced ionization (EI), to an atomic-like response. The energy spectra of the ions show no dependence on the intensity and has its source in dissociative molecular ionization. A classical model of an aligned C-Cl ion is used to model the interaction. Following an initial molecular ionization process, our results show EI is a driving influence in the formation of low charge states until ionization become atomic-like and involves tightly bound ion states whose ionization is unaffected by nearest neighbor ions of similar ion charge.

Strong-field ionization of CH3Cl: proton migration and association

“…In this regime, the rate of single ionization of CH 3 Cl is higher than that of double or triple ionization. As the intensity is increased, the single ionization rate increases monotonically and then saturates at intensities beyond 1.2 × 10 14 W cm −2 (in agreement with Grugan et al 51 ). This saturation intensity I sat , which can be attributed to the depletion of ground states at high intensities, 52 depends on the ionization potential ( I p ) of the molecule.…”

“…In contrast to the S1 structure, the angle between H4, C2, and Cl1 decreased to 1141 from 131.81, while the +124 increased to 132. 51 We arranged the two hydrogen atoms in such a way that they could be rotated around the hydrogen atom connected to the C-Cl bond to determine the initial transition state. In this way, we were able to create a structure A with one imaginary frequency, i298.58 cm À1 , which corresponds to the H3H5 group's out-of-plane rotation.…”

“…23 The fragmentation of CH 3 Cl has been studied extensively using ion bombardment, 24,25 synchrotron radiation, [26][27][28][29] and femtosecond lasers. [30][31][32] H n + (n = 1-3) and HCl + formation during the photodissociation of CH 3 Cl has been of interest for many years. Duflot et al studied the various two-and threebody dissociation channels of the CH 3 Cl dication using the complete active space self-consistent field (CASSCF) method.…”

Fragmentation dynamics of CH3Clq+ (q = 2,3): theory and experiment

“…Recently, CH 3 Cl became the first organohalogen to be detected in the interstellar space. 4 A number of studies have been performed on the chloromethane molecule under intense laser fields, [5][6][7][8][9] both valence and core photoionization, 2,10-17 ion impact, 3,18 electron impact 19,20 and double-charge-transfer spectroscopy. 21 For instance, Ma et al 6 treated in 2017 the Coulomb explosion and fast H-atom rearrangement after intense laser field ionization of CH 3 Cl.…”

Quantum Chemical Rovibrational Characterization of CH2ClH+, a Low-Energy Isomer of Ionized Chloromethane

“…With some charged chlorohydrides already known in the ISM, ionized chloromethane is a natural next step for astrophysical examination. The ionization potential of CH 3 Cl is experimentally known to be 11.2896 eV, less than that of O 2 . − Additionally, while the lowest energy isomer is the simple CH 3 Cl + , the CH 2 ClH + isomer in the methyl analogue of chloronium is low-lying . While the neutral form of CH 2 ClH would have too much repulsion in the C–Cl bond, the cation does not have an electron in an antibonding orbital in this region similar to the oxywater cation and its sulfur analogue. − Furthermore, the electron deficiency of the chlorine atom in the cation is more satiated by sharing electrons with two groups, methylene and a proton in this case …”