Photoionization of iodine atoms: Angular distributions and relative partial photoionization cross-sections in the energy region 11.0–23.0 eV

Eypper, Marie; Innocenti, Fabrizio; Morris, Alan; Dyke, John M.; Stranges, Stefano; West, John B.; King, G C

doi:10.1063/1.3469798

Cited by 9 publications

(1 citation statement)

References 36 publications

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“…At R eq = 5 a.u. the most loosely bound electron (E P f = −19.2 eV [21]) can easily overcome the potential barrier towards I 4+ while electron transfer is blocked beyond R crit = 9.73 a.u.. R crit can be predicted for all asymmetric charges via Eq. 5.…”

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Electron Rearrangement Dynamics in DissociatingI2n+Molecules Accessed by Extreme Ultraviolet Pump-Probe Experiments

et al. 2014

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The charge rearrangement in dissociating I n+ 2 molecules is measured as a function of the internuclear distance R using XUV pulses delivered by the free-electron laser (FEL) in Hamburg. Within an XUV pump-probe scheme the first pulse initiates dissociation by multiply ionizing I 2 , and the delayed probe pulse further ionizes one of the two fragments at a given time, thus triggering charge rearrangement at a well-defined R. The electron transfer between the fragments is monitored by analyzing the delay-dependent ion kinetic energies and charge states. The experimental results are in very good agreement with predictions of the classical over-the-barrier model demonstrating its validity in a thus far unexplored quasimolecular regime relevant for FEL, plasma and chemistry applications.The dynamics of charge relaxation, rearrangement and equilibration at the transition between chemically bound and unbound systems is essential for understanding many chemical [1, 2] and plasma reactions [3,4]. It is also crucial for the imaging of biomolecules with atomic resolution, a key application of Free-Electron Lasers (FELs). Here, the idea is to take a snapshot of the molecule by irradiating the system with intense ultra-short (< 100 fs) X-ray pulses before it is damaged [5]. Recent experiments on nano-crystalized lysozyme, however, have shown that the photon-induced damage leads to a scattering pattern that is different from what is expected for the intact molecule even for X-ray pulses as short as 70 fs [6]. Photon absorption is strongly localized at constituents with high atomic numbers, often having more than an order of magnitude larger cross sections as compared to H or even C atoms [7]. Therefore, it is crucial to understand the underlying ultrafast electronic and nuclear rearrangement dynamics in order to develop improved damage models that take into account the spatio-temporal spread of the locally induced charge.Localized photon absorption efficiently triggers atomic movement and electron rearrangement across the entire molecular ion, mainly leading to its fragmentation. In a recent study methylselenol [8] and ethylselenol [9] molecules, containing one heavy selenium atom as photoabsorption center, were irradiated with single intense 5 fs X-ray pulses. From the observed charge-state distributions and the fragments' kinetic energies it could be concluded that even for such short pulses ultrafast charge rearrangement takes place, accompanied by considerable atomic displacements which is relevant for imaging with atomic resolution. However, the central question concerning the underlying time and length scales remained open. In this work we present experimental results on the electron transfer between two iodine ions at freely chosen internuclear distances R. A dissociation of the I 2 molecule is triggered by multiple ionization with a femtosecond pump pulse [10]. The evolving system is then further ionized by the delayed probe pulse. Depending on the time delay, or the corresponding internuclear distance, and the charg...

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confidence: 99%