New article in Report on Progress in Physics - Ltaief Ben Ltaief
Collisional secondary ionization is found to be more efficient than the direct process. In collaboration with a group of researchers from IFA and abroad, Ltaief Ben Ltaief's latest research results have been published in Report on Progress in Physics (ROPP).

A groundbreaking study conducted at IFA at ASTRID II by an international team led by Ltaief Ben Ltaief and Marcel Mudrich has provided new insights into how a heterogeneous nanosystem—helium nanodroplets doped with lithium (Li) atoms—responds to high-energy extreme ultraviolet (XUV) radiation. Using velocity-map imaging detection technique, the researchers meticulously tracked an entire sequence of ionization events starting from an initial photoionization event by XUV photons that leads to emission of fast photoelectrons inside the droplets, to the formation of helium excited states within the droplets by photoelectron impact excitation and electron-ion recombination until the creation of charged products as a result of the decay of these excited states. Importantly, they observed that the dopants lithium atoms are ionized at the last step of the cascade via the so called interatomic Coulombic decay (ICD).
A key and surprising observation was the remarkable high efficiency of the ICD process occurring in these heterogenous nanosystems. The study revealed that ICD, responsible for ionizing the lithium atoms, primarily occurs from the triplet excited states of helium atoms or helium molecules. This finding challenges previous observations on ICD, which predominantly occurs from singlet states prepared in optically excited helium atoms.
These findings carry broader implications, suggesting that ICD processes involving triplet states may play a significant role in other condensed-phase systems exposed to ionizing radiation, including biological matter. This insight could help develop better radiation protection strategies and improve radiation-based therapies, ultimately protecting human health from radiation damage.