Time-resolved THz Stark spectroscopy

TL;DR

This paper presents THz Stark spectroscopy using intense terahertz pulses to study molecular responses, enabling time-resolved analysis at ambient conditions and revealing dynamical field effects.

Contribution

It introduces a novel THz Stark spectroscopy method that overcomes limitations of conventional techniques, allowing time-resolved studies without sample freezing.

Findings

Successful demonstration on two molecular systems

Comparison with conventional Stark spectroscopy and calculations

Observation of dynamical field effects

Abstract

We introduce THz Stark spectroscopy by using intense single-cycle terahertz pulses as the electric field source and monitoring the induced spectral response of an isotropic molecular ensemble with a coincident femtosecond supercontinuum pulse. THz Stark spectroscopy offers several advantages over conventional Stark spectroscopy and opens previously inaccessible perspectives. Most importantly, THz pulses oscillate faster than typical molecular rotations and consequently eliminate the requirement to freeze the samples to prevent poling effects. Hence, THz Stark spectroscopy allows for time-resolved studies at arbitrary temperatures, specifically ambient conditions more relevant to physiological or operative conditions. Moreover, dynamical field effects, e.g., higher order Stark contributions or hysteresis effects (non-Markovian behavior), can be studied on the time scales of molecular vibrations or rotations. We demonstrate THz Stark spectroscopy for two judiciously selected molecular systems and compare the results to conventional Stark spectroscopy and first principle calculations.