Abstract
The interaction of CH3I molecules with 100 fs 800 nm linearly polarized laser fields has been investigated at the intensity region from 2.6 × 1014 to 5.8 × 1014 W/cm2 by means of a velocity map imaging method. The kinetic energy distribution of the various atomic fragment ions Iq+ (q = 1–3) has been measured and reproduced by a fit of multiple Gaussian functions. Several dissociative ionization and Coulomb explosion channels were identified for Iq+ (q = 1–3). As expected for a geometric alignment dominated interaction process the anisotropic angular recoil distributions of the atomic ion fragments are peaked in the laser polarization direction. The kinetic energy release (KER) of Iq+ (q = 1–3) depending upon the laser intensity has been investigated. The relative weight of the various contributions from the identified dissociative ionization (DI) and Coulomb explosion (CE) channels is found to depend strongly on the laser intensity.Graphical abstract
Highlights
The interaction of strong laser fields with molecules, about 2 decade’s an active area of research already, forms a subject of exploration up till the present [1,2,3,4,5,6,7,8,9,10,11,12,13,14]
1−2) parent ions, and the fragment iothdeinferaiognmse, nItq+C(Hq+k=(k1−=3).0T−h3e) presence of the multiple charged fragment ions indicates that a Coulomb explosion (CE) process in the intense laser field is taking place
These ions are produced in quantities that are comparable to those of singly charged iodine ions, which indicates a competition between Coulomb explosion and multi-photon dissociative ionization (MPDI)
Summary
The interaction of strong laser fields with molecules, about 2 decade’s an active area of research already, forms a subject of exploration up till the present [1,2,3,4,5,6,7,8,9,10,11,12,13,14]. When the intensity of a laser beam approaches around 1014 W/cm, the strength of its electric field is comparable to that experienced by the molecular valence electrons. This gives rise to interesting phenomena, such as multi photon ionization (MPI), dissociative ionization (DI) [1,2,3,4], field ionization [5,8], Coulomb explosion (CE) [6,7,9,10,11], field assisted dissociation and electron re-scattering [12,13,14]. The kinetic energy disposed into a CE fragment ion turns out to be substantially less than that expected for a prompt dissociative ionization of a parent molecule at Contribution to the Topical Issue: “Dynamics of Molecular Systems (MOLEC 2016)”, edited by Alberto Garcia-Vela, Luis Banares and Maria Luisa Senent
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