Mainz 2026 – scientific programme

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MO: Fachverband Molekülphysik

MO 2: Chirality I

MO 2.3: Talk

Monday, March 2, 2026, 12:30–12:45, P 110

Bottom-up Analysis of Ro-Vibrational Helical Dichroism — •Mateja Hrast, Georgios M. Koutentakis, Mikhail Maslov, and Mikhail Lemeshko — Institute of Science and Technology Austria, Klosterneuburg, Austria

Helical dichroism (HD) is a proposed method for the resolution of molecular chirality, employing the orbital angular momentum (OAM) of light and hypothesized to arise from electric-dipole-electric-quadrupole interactions. Going beyond the conventional assumptions, we propose a general theoretical framework for the analysis of HD, based on molecular symmetries and rotational eigenstates. Using our recently developed model of molecule-light interaction Hamiltonian we establishing an explicit link between chiral resolution and orbital angular momentum (OAM) exchange in light-matter interaction. Tracing microscopic mechanisms of the OAM transfer, we derive the rotational selection rules, which clearly establish that HD emerges only from the spin-orbit coupling of light, even for beams without the far-field OAM. Our findings refine the conditions for observing HD, provide a tool to re-examine the outcome of prior experiments, and guide future designs for chiral sensing with structured light.

Keywords: Helical dichroism; Vortex beams; Chirality; Spin-orbit coupling