Colóquio 23/09/2022: Nonlinear optical microscopy: from 2D materials to the Alzheimer’s disease

Sobre este evento

In this talk we will talk about the applications of non-linear optical microscopies to study novel 2D materials and also its applications to biological problems, such as for the early
diagnosis of Alzheimer disease. We will give a brief introduction on non-linear optics, the recent developments in 2D materials and how to use non -linear microscopy techniques to extract its physical properties. For 2D semiconducting dichalcogenides (TMDs) we have observed efficient SHG from an odd number of layers due to the absence of inversion symmetry and to determine the crystallographic orientation [1]. More recently we have also shown that SHG can be a useful tool to identify and characterize grain boundaries, edges and interfaces in different 2D materials [2,3]. Moreover with the combination of SHG and four wave mixing (FWM) spectroscopies, we were able observe a large enhancement of then non-linear signals close to the exciton and trion energies of different 2D TMDs [4]. Besides the applications in 2D materials, we will review the application of Stimulated Raman Scattering (SRS) in biological systems, a technique that combines the advantages of chemical characterization of Raman spectroscopy and the high throughput of nonlinear optical techniques. We will present our results of different spectral fingerprints of beta-amyloid plaques in mice brains that could be used as a future platform for label-free diagnosis of Alzheimer disease [5].

[1] L. M. Malard et al., Phys. Rev. B 87, 201401 (2013).
[2] B. R. Carvalho et al., Nano Lett. 20, 284 (2020).
[3] F. Souza et al., 2D Materials 8, 035051 (2021).
[4] L. Lafeta et al., 2D Materials 8, 035010 (2021).
[5] R. Cunha et al., Analyst 146, 2945 (2021).

Tópico: Colóquio do Departamento de Física
Hora: 23 set. 2022 10:00 da manhã São Paulo

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