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SYAO: Symposium New Avenues in Molecular Alignment and Orientation

SYAO 1: New Avenues in Molecular Alignment and Orientation

SYAO 1.4: Hauptvortrag

Freitag, 14. März 2025, 16:00–16:30, HS 1+2

Coherent rotational control of gas phase molecular dipoles by concerted Terahertz and Near-IR pulses — •Sharly Fleischer — School of Chemistry, Tel Aviv University, Israel — Tel Aviv Center for Light-Matter Interaction, Tel Aviv University, Israel

The orientation and alignment of gas-phase molecular ensembles is a long-pursued goal in physics and chemistry. Short Near-IR (NIR) pulses are commonly used to ALIGN molecules by exerting torque via the anisotropic polarizability tensor of the molecules. Intense single-cycle terahertz fields (THz) ORIENT the molecules via resonant dipole-field interaction. These above-mentioned 'rotational drivers' (NIR and THz) have been vastly utilized selectively, however their concerted application remains very scarce. In this talk I will focus on two uniquely desirable rotational responses provided by judiciously orchestrated rotational excitations by BOTH THz and NIR pulses.

1)Orientation echo spectroscopy: I will present an efficient scheme for orientation echoes where the first pulse (THz) induces rotational dynamics that is rephased by a second NIR pulse. The dynamics of the multi-level rotational system is governed by the interference of multiple transition pathways within the rotational state manifold and will be discussed.

2)Enhanced molecular orientation at ambient temperatures: I will present a practical scheme for enhanced degree of orientation via concerted NIR and THz excitations. Complementary calculations predict far larger enhancements (~20-fold with respect to that induced by the THz field alone).

Keywords: Molecular orientation and alignment; Rotational spectroscopy; Rotational echo spectroscopy