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O: Fachverband Oberflächenphysik

O 80: Scanning Probe Microscopy: Light Matter Interaction at Atomic Scales II

O 80.7: Vortrag

Donnerstag, 21. März 2024, 12:00–12:15, MA 041

TDDFT study of the orthosilicic acid molecule under electrostatic field and laser irradiation — •Tommaso Morresi — ECT* - FBK, Trento, Italy

The Tomographic Atom Probe (TAP) is a rapidly developing technique in the field of condensed matter analysis. Recently, a combination of TAP with intense THz pulses to control ion emission has been proposed [1]. This mechanism enables high spatial resolution and chemical sensitivity. In this configuration, the TAP analysis could be extended to bio-samples as an alternative to 4D microscopy. This investigation is the ultimate goal of the EIC Pathfinder project MIMOSA. Within this collaborative framework with a strong experimental endeavour, the theoretical understanding and computational modelling of the atom evaporation mechanism is of paramount importance. In this work, we study the interaction of THz-lasers with the orthosilicic acid molecule, which is the main ingredient of the matrix embedding the bio-material in the experimental setup. By using time-dependent density functional theory for electrons in combination with molecular dynamics for ions, we analyse the dynamics of laser-assisted field evaporation of OH ions from the molecule. While the scheme is similar to the one proposed in Ref. [2], the novelty of this work is mainly represented by the frequency of the laser in TDDFT simulations. We show the critical fields allowing the evaporation of OH ions in the THz regime and also the effect of additional external electrostatic fields on top of the time-dependent ones. [1] - A. Vella et al., Sci. Adv. 7, 7 (2021) [2] - E.P. Silaeva et al., PRB 92, 155401 (2015)

Keywords: TDDFT and Ehrenfest dynamics; orthosilicic acid molecule; evaporation dynamics