  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.
