לוח שנה משולב

Zoom: https://weizmann.zoom.us/j/96278790117?pwd=T1ZjaHlxQjlEQkFIbE12UDJCazNwZz09

Two-dimensional layered (van-der-Waals) heterostructures, made by stacking different monolayers of semiconducting transition-metal dichalcogenides, have been drawing much attention as versatile platforms for studying fundamental solid-state phenomena and for designing opto-electronic devices. Interlayer excitons, electron-hole pairs that bind to each other across the interlayer spacing in these heterostructures, hold promise as key tools for probing the interlayer interface structure, and for exploring many-body interactions(1). With long lifetimes, spin polarization, and electric tunability, interlayer excitons are also promising as flexible information carriers(2, 3). However, they were mostly studied through the scope of their visible light emission, missing essential properties such as their momentum-space image or their absorption strength, necessary for rigorous study of their many-body interactions and potential applications.
In this talk I will present our recent studies aimed at measuring such unknown interlayer exciton properties and their dependence on the heterostructure. I will show a new interlayer exciton in WSe2/MoS2 heterostructures which we discovered based on its light emission in infra-red wavelengths, rather than in the visible range(4). I will demonstrate its properties as inferred from its optical interrogation. Then, I will present the quantitative measurement of the elusive optical absorption spectrum of interlayer excitons using electric-field modulation spectroscopy, essential for coherent coupling of light to those excitons(5). Finally, I will reveal how time- and angle-resolved photoemission spectroscopy is used to image the interlayer exciton in momentum-space, yielding its size and binding energy, so far inaccessible through optics(5).

SARS-CoV-2 more contagious mutations are spreading rapidly. In vitro affinity maturation of the receptor-binding domain (RBD) towards ACE2, resulted in more contagious mutations, S477N, E484K, and N501Y to be among the first selected, including the British and South African variants. Plotting the binding affinity against the incidence of different RBD mutations in the population supported correlation between the two. Further in vitro evolution provides guidelines towards potentially new evolving mutations with even higher infectivity.

For more details see Preprint: https://www.biorxiv.org/content/10.1101/2021.01.06.425392v2

Zoom Link:
https://weizmann.zoom.us/j/97142508810?pwd=S2Voc3BMYnh6RmFTYUxLbUFjQXRGZz09






Until recently, computational studies of chemical reactivity were exclusively dealt with using quantum mechanical approaches, which severely limited the system's size and accessible time scales for simulation.
To bypass the need to solve Schrodinger's equation, and facilitate large-scale simulations for up to millions of atoms, both accurate and efficient models of the chemical bond have to be constructed.
I will present recent advances in the field of modeling chemical reactions in large-scale, complex systems (i.e. "dirty chemistry"), with a particular focus on ReaxFF reactive molecular dynamics.
Prominent applications from recent years will be highlighted, including: (a) discovery of the underlying operation principles of a novel laser-based mass-spectrometry technique,
and (b) prediction of the surprising chemistry that leads to the formation of several key precursors to biomolecules of life upon the collapse of a "primordial bubble".
Finally, I will present a new ReaxFF formulation that opens exciting new avenues for orders of magnitude more accurate simulations for long time scales.