Starts 14 May 2025 11:00
Ends 14 May 2025 12:00
Central European Time
CMSP Seminar (Atomistic Simulation Seminar Series): Modelling photoinduced electron dynamics for ultrafast processes in molecular and composite systems
Leonardo Building
Leonardo Building - Luigi Stasi Seminar Room
Emanuele Coccia
(University of Trieste)
Abstract:
The interaction of light with matter is the subject of boundless research, ranging from astrophysics to materials science to biology and medicine. Theory is essential to interpret experimental outcomes and predict new features from, e.g., photophysics, photochemistry and photcatalytic studies. Clearly, time-dependent quantum mechanics is the appropriate tool for that purpose, allowing one to model fast and ultrafast (from picoseconds to attoseconds) dynamics occurring in chemical systems, and to properly simulate spectroscopy. Among the countless fields of research in which the role of light plays a key role in inducing transformations, molecular nanoplasmonics has seen growing interest develop around it, both experimentally and theoretically. Molecular nanoplasmonics [1] exploits collective electron excitations in metal nanostructures to enhance and control properties of molecules under the influence of light. A theoretical multiscale time-domain approach [2] was applied to study the selectivity toward methane in the photocatalytic hydrogenation of carbon dioxide in the presence of a rhodium nanocube [3], and to verify the plasmon enhancement of the circular dichroism signal in chiral molecules [4]. Then, I present our recent work on the development of ab initio time- domain methods for simulating high-harmonic generation (HHG) spectra [5] of aligned or non-aligned molecules. HHG is a highly nonlinear process occurring in strong-field conditions. We show how, in the presence of a linearly polarised pulse, that the interference among ionization channels modulate the shape of the spectrum: an example is given by carbon dioxide [6], with a specific pulse polarisation. As a second house, we show how to modulate the selection rules in molecules such as methane and fluoromethane [7], interacting with two-colour bicircular (BCR) fields, by changing the relative orientation and geometry of the spectroscopic target. In conclusion, results on HHG spectra of a chiral molecule, such as methyloxirane, with BCR pulses [7] are shown and discussed.
References
[1] L. Novotny and B. Hecht, Principles of Nano-Optics, Cambridge University Press (2012)
[2] E. Coccia, J. Fregoni, C. A. Guido, M. Marsili, S. Pipolo and S. Corni, J. Chem. Phys., 153, 200901 (2020)
[3] G. Dall’Osto, M. Marsili, M. Vanzan, D. Toffoli, M. Stener, S. Corni and E. Coccia, J. Am. Chem. Soc., 146, 2208 (2024); G. Dall’Osto, M. Vanzan, S. Corni, M. Marsili and E. Coccia, J. Chem. Phys., 161, 124103 (2024)
[4] L. Biancorosso, P. D’Antoni, S. Corni, M. Stener and E. Coccia, J. Chem. Phys., 161, 214104 (2024)
[5] M. Lewenstein, P. Balcou, P., M. Y. Ivanov, A. L’Huillier, and P. B. Corkum, Phys. Rev. A, 49, 2117 (1994)
[6] M. Marchetta, C. Morassut, J. Toulouse, E. Coccia and E. Luppi, J. Chem. Phys., 161, 204111 (2024
[7] M. Marchetta, D. Facciala’, E. Luppi, C. Vozzi and E. Coccia, in preparation
The interaction of light with matter is the subject of boundless research, ranging from astrophysics to materials science to biology and medicine. Theory is essential to interpret experimental outcomes and predict new features from, e.g., photophysics, photochemistry and photcatalytic studies. Clearly, time-dependent quantum mechanics is the appropriate tool for that purpose, allowing one to model fast and ultrafast (from picoseconds to attoseconds) dynamics occurring in chemical systems, and to properly simulate spectroscopy. Among the countless fields of research in which the role of light plays a key role in inducing transformations, molecular nanoplasmonics has seen growing interest develop around it, both experimentally and theoretically. Molecular nanoplasmonics [1] exploits collective electron excitations in metal nanostructures to enhance and control properties of molecules under the influence of light. A theoretical multiscale time-domain approach [2] was applied to study the selectivity toward methane in the photocatalytic hydrogenation of carbon dioxide in the presence of a rhodium nanocube [3], and to verify the plasmon enhancement of the circular dichroism signal in chiral molecules [4]. Then, I present our recent work on the development of ab initio time- domain methods for simulating high-harmonic generation (HHG) spectra [5] of aligned or non-aligned molecules. HHG is a highly nonlinear process occurring in strong-field conditions. We show how, in the presence of a linearly polarised pulse, that the interference among ionization channels modulate the shape of the spectrum: an example is given by carbon dioxide [6], with a specific pulse polarisation. As a second house, we show how to modulate the selection rules in molecules such as methane and fluoromethane [7], interacting with two-colour bicircular (BCR) fields, by changing the relative orientation and geometry of the spectroscopic target. In conclusion, results on HHG spectra of a chiral molecule, such as methyloxirane, with BCR pulses [7] are shown and discussed.
References
[1] L. Novotny and B. Hecht, Principles of Nano-Optics, Cambridge University Press (2012)
[2] E. Coccia, J. Fregoni, C. A. Guido, M. Marsili, S. Pipolo and S. Corni, J. Chem. Phys., 153, 200901 (2020)
[3] G. Dall’Osto, M. Marsili, M. Vanzan, D. Toffoli, M. Stener, S. Corni and E. Coccia, J. Am. Chem. Soc., 146, 2208 (2024); G. Dall’Osto, M. Vanzan, S. Corni, M. Marsili and E. Coccia, J. Chem. Phys., 161, 124103 (2024)
[4] L. Biancorosso, P. D’Antoni, S. Corni, M. Stener and E. Coccia, J. Chem. Phys., 161, 214104 (2024)
[5] M. Lewenstein, P. Balcou, P., M. Y. Ivanov, A. L’Huillier, and P. B. Corkum, Phys. Rev. A, 49, 2117 (1994)
[6] M. Marchetta, C. Morassut, J. Toulouse, E. Coccia and E. Luppi, J. Chem. Phys., 161, 204111 (2024
[7] M. Marchetta, D. Facciala’, E. Luppi, C. Vozzi and E. Coccia, in preparation