Multi-channel photodissociation and XUV-induced charge transfer dynamics in strong-field-ionized methyl iodide studied with time-resolved recoil-frame covariance imaging

Abstract

The photodissociation dynamics of strong-field ionized methyl iodide (\ce{CH3I}) were probed using intense extreme ultraviolet (XUV) radiation produced by the SPring-8 Angstrom Compact free electron LAser (SACLA). Strong-field ionization and...

Nonadiabatic Coupling Effects in the 800 nm Strong-Field Ionization-Induced Coulomb Explosion of Methyl Iodide Revealed by Multimass Velocity Map Imaging and Ab Initio Simulation Studies

“…This study reports velocity map images of the (I q + ( q ≤ 6), CH n + ( n = 0–3), CH n 2+ ( n = 0, 2), and C 3+ fragment ions arising in the one color SFI of jet-cooled CH 3 I molecules following excitation with 40 fs, 805 nm laser pulses at three different peak intensities in the range I ≈ 2.6 × 10 14 to 1.3 × 10 15 W cm –2 (260–1300 TW cm –2 ) along with ( I -dependent) velocity and angular distributions derived therefrom that are broadly consistent with previous studies (mostly at somewhat lower peak intensities). − Complementary ab initio trajectory calculations of the CE of CH 3 I Z + cations with Z ≤ 14 (i.e., up to the limit corresponding to removal of all valence electrons) serve to identify three classes of behavior: The CE of the “low” multicharge states of CH 3 I (i.e., cations with Z = 2 and 3) can be adequately described using a diatomic-like representation–as shown previously . For Z > 3, however, the present work clearly shows the multidimensionality of the CE dynamics.…”

“…Several ultrafast NIR − and X-ray − laser-induced CE studies of CH 3 I have been reported previously. Early studies by Graham et al at high peak intensities ( I ∼ 10 16 W cm –2 ) determined angular distributions for I q + ( q ≤ 7), CH n + ( n = 0–3), CH 2 2+ , C p + ( p ≤ 4) and H + fragment ions, all of which were found to maximize parallel to the electric polarization vector (ε) of the NIR radiation.…”

UV-induced dissociation of CH2BrI probed by intense femtosecond XUV pulses

“…The photon energy can often be chosen such that the ionization is either site-specific or distributed over several atomic constituents, providing the opportunity to tailor the probe pulse to address different parts of the molecule. When performing Coulomb explosion experiments with femtosecond pulses from free-electron lasers (FELs), molecular dynamics and fragmentation processes of gas-phase samples can be studied in a time-resolved fashion [7][8][9][10][11] . todissociation of bromoiodomethane, CH 2 BrI, with the intent to investigate charge transfer after XUV innershell ionization at different molecular sites.…”

Multi-Particle Three-Dimensional Covariance Imaging: “Coincidence” Insights into the Many-Body Fragmentation of Strong-Field Ionized D2O

“…Covariance between two variables A and B (in our case, three-dimensional ion velocity distributions) is defined as where angled brackets refer to the mean over a series of N observations (in the current work, laser shots). Although performing experiments under high count rate conditions necessarily forfeits event-by-event correlated information afforded by coincidence analysis, the covariance methodology can extract the same correlations when averaging over a large ensemble of observations, as is the case in a typical experiment. − Following its initial application to time-of-flight mass spectrometry experiments, covariance mapping has been applied to a range of two-dimensional VMI experiments − and recently a three-dimensional VMI study of the two-body dissociations of CF 3 I 2+ . Recent work by Suits and co-workers combined covariance analysis with a three-dimensional imaging technique to study the Coulomb explosion dynamics of chlorocarbonylsulfenyl chloride molecules .…”

“…For covariance, the maximum count rate is determined by the maximum distinguishable number of events of the hit-finding algorithm. If one is limited by 15 hits per shot (a rather conservative estimate, given the higher count rates of previous covariance imaging work ,, ), then the ion–ion covariance measurements could be performed with count rates about 90 times higher. Electron–ion covariance measurements would require count rates about half the value.…”