Special Seminar
Name: Sindhana Pannir-Sivajothi
Affiliation: Department of Chemistry, University of California, Berkeley, CA, USA
Title: Controlling molecular reactivity and spin with light and strong light-matter coupling
Date & Time: Wednesday, 29th October at 11:00 a.m.
Venue: Through Microsoft teams
Microsoft teams link: SSCU- Special Seminar by Dr. Sindhana Pannir-Sivajothi on Wednesday, 29th October 2025 at 11:00 a.m. through Microsoft Teams | Meeting-Join | Microsoft Teams
Abstract:
Light-matter interactions play a central role in chemistry, from spectroscopy and photochemistry to the emerging control of electron spin in molecular qubits. In the first part, I will present theoretical results showing how strong light-matter coupling modifies chemical and physical processes, and argue that radiative heat transfer is a key, and often overlooked, driver in vibropolaritonic chemistry [1,2]. I then propose a strategy to enhance these effects via polariton condensation [3] and discuss how the same framework enables spectroscopic measurement of small geometry changes [4]. In the second part, I address spin control with light. Experiments have shown that electron transmission through chiral molecules is spin-selective — the chirality-induced spin selectivity (CISS) effect — producing spin polarization without magnetic fields. While CISS is usually attributed to static molecular chirality set by nuclear geometry, we predict that achiral donor–acceptor systems excited with circularly polarized light develop transient chirality during their excited-state dynamics, leading to spin-polarized transport [5]. This light-induced mechanism offers a complementary pathway to conventional CISS for manipulating spins.
References:
[1] Z. T. Brawley*, S. Pannir-Sivajothi*, J. E. Yim*, Y. R. Poh, J. Yuen-Zhou, and M. Sheldon, Vibrational weak and strong coupling modify a chemical reaction via cavity-mediated radiative energy transfer, Nat. Chem. 17, 439–447 (2025).
[2] S. Pannir-Sivajothi and J. Yuen-Zhou, Blackbody radiation and thermal effects on chemical reactions and phase transitions in cavities, ACS Nano 19 (10), 9896–9905 (2025).
[3] S. Pannir-Sivajothi, J. A. Campos-Gonzalez-Angulo, L. A. Martínez-Martínez, S. Sinha, and J. Yuen-Zhou, Driving chemical reactions with polariton condensates, Nat. Commun. 13, 1645 (2022).
[4] S. Pannir-Sivajothi and J. Yuen-Zhou, Precision Franck-Condon spectroscopy from highly-excited vibrational states, arXiv preprint arXiv:2401.10384 (2024).
[5] S. Pannir-Sivajothi and D. T. Limmer, Spin selectivity of circularly polarized light induced electron transfer in achiral donor-acceptor complexes (under preparation).