Orientation Echoes via Concerted Terahertz and Near-IR excitation

Abstract

A new and efficient method for orientation echo spectroscopy is presented and realized experimentally. The excitation scheme utilizes concerted rotational excitations by both ultrashort terahertz and near-IR pulses and its all-optical detection is enabled by Molecular Orientation Induced Second Harmonic method [J.Phys.Chem.A 126, 3732-3738 (2022)]. The method provides practical means for orientation echo spectroscopy of gas phase molecules and highlights the intriguing underlying physics of coherent rotational dynamics induced by judiciously-orchestrated interactions with both resonant (terahertz) and nonresonant (NIR) light pulses.