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Light & Matter Seminar: Dr David Ayuso Molinero – Ultrafast, all-optical, and highly enantio-sensitive imaging of molecular chirality
May 17 @ 2:00 pm - 3:00 pm
Join Dr David Ayuso Molinero from Imperial College London for a Light & Matter Seminar entitled ‘Ultrafast, all-optical, and highly enantio-sensitive imaging of molecular chirality.’ Those external to King’s wishing to attend should email this address
Just like our hands, chiral molecules exist in pairs of opposite “mirror twins” called enantiomers, which behave identically unless they interact with another chiral “object”. Distinguishing them is vital, e.g. as most biomolecules are chiral. Traditional optical methods rely on the (chiral) helix that circularly polarised light draws in space. However, the micron-scale pitch of this helix, determined by the wavelength, is orders of magnitude larger than the Angstrom-scale size of the molecules. As a result, the tiny molecules perceive this helix as a planar circle, hardly feeling its chirality. This leads to extremely weak enantio-sensitivity and creates a justified impression that chiral discrimination is difficult, particularly on ultrafast timescales.
We can overcome this fundamental limitation by creating synthetic chiral light , which is locally chiral: tip of the electric-field vector draws a chiral (three-dimensional) Lissajous figure in time, at each point in space. It allows us to suppress the nonlinear optical response of a selected molecular enantiomer while maximising it in its mirror twin.
In this presentation, I will show how we can shape the polarisation of light in time and in space in order to maximise the enantio-sensitive response of chiral molecules on ultrafast timescales [1-7]. As we shall see, such tailored waveforms allow us to imprint the medium’s handedness into different enantio-sensitive observables: the total intensity of harmonic light [1-3], the direction of harmonic emission [3-5], or the polarisation of the nonlinear optical response [6,7]. Our numerical and semi-analytical modelling reveals that, in all these cases, we can reach the ultimate limit of enantio-efficiency: 100%. This creates exciting opportunities for imaging chiral molecules and ultrafast chiral dynamics, as well as new routes for enantio-sensitive control of chiral matter.
 D. Ayuso, O. Neufeld, A. F. Ordonez, P. Decleva, G. Lerner, O. Cohen, M. Ivanov, and O. Smirnova, Nature Photonics 13, 866 (2019)
 D. Ayuso, Phys. Chem. Chem. Phys. 24, 10193-10200 (2022)
 L. Rego and D. Ayuso, ArXiv:ArXiv:2206.01680 (2022)
 D. Ayuso, A. F. Ordonez, P. Decleva, M. Ivanov and O. Smirnova, Nature Communications 12, 3951 (2021)
 L. Rego and D. Ayuso, ArXiv:2206.01719 (2022)
 D. Ayuso, A. F. Ordonez, M. Ivanov and O. Smirnova, Optica 8, 1243 (2021)
 O. Neufeld, D. Ayuso, P. Decleva, M. Y. Ivanov, O. Smirnova and O. Cohen, Physical Review X 9, 031002 (2019)