Nonlinear 2D rotational spectroscopy of gas-phase molecules has been performed in the terahertz (THz) frequency range by researchers from the USA and Israel. Two time-delayed collinear THz pulses were generated from a LiNbO3 crystal by optical rectification and focused into a gas cell containing CH3CN at room temperature at 70 torr. The field strength of each pulse was 400 kV cm−1 inside the sample gas cell. The transmitted THz pulses were detected by electro-optical sampling with a ZnTe crystal. The 2D time-domain nonlinear signal was recorded as a function of the time difference between the THz pulses and the read-out delay time. The team observed four types of third-order signal that arose from three THz field interactions with the molecule dipoles: rephasing (photon echo), non-rephasing, two-quantum, and pump–probe signals. The different phenomena could be distinguished from the time-domain traces of the nonlinear signal. The 2D rotational spectroscopy permitted direct measurement of rotational dephasing, population relaxation dynamics and spectral correlations.
Rights and permissions
About this article
Cite this article
Horiuchi, N. 2D photon echo. Nature Photon 10, 751 (2016). https://doi.org/10.1038/nphoton.2016.245
Published:
Issue Date:
DOI: https://doi.org/10.1038/nphoton.2016.245