Triple sum-frequency (TSF) spectroscopy measures multidimensional spectra by resonantly exciting multiple quantum coherences of vibrational and electronic states. In this work we demonstrate pump-TSF-probe spectroscopy in which a pump excites a sample and some time later three additional electric fields generate a probe field which is measured. We demonstrate pump-TSF-probe spectroscopy on polycrystalline, smooth, thin films and spiral nanostructures of both MoS2 and WS2. The pump-TSF-probe spectra are qualitatively similar to the more conventional transient-reflectance spectra. While transient-reflectance sensitivity suffers under low surface coverage, pump-TSF-probe sensitivity is independent of the sample coverage and nanostructure morphologies. Our results demonstrate that pump-TSF-probe is a valuable methodology for studying microscopic material systems.
@article{arxiv.1909.06445,
title = {Pump-triple sum-frequency-probe spectroscopy of transition metal dichalcogenides},
author = {Darien J. Morrow and Daniel D. Kohler and Yuzhou Zhao and Song Jin and John C. Wright},
journal= {arXiv preprint arXiv:1909.06445},
year = {2019}
}