The concept of multidimensional spectroscopy was developed in nuclear magnetic resonance in the 1960s and 1970s. Its ability to reveal coupling between nuclear spins was revolutionary. Over the last couple of decades, the method has been ported to the optical domain, where it has been similarly transformative by simplifying the observation and characterization of the interactions between optically induced excitations. One of the challenges was the phase fluctuations inherent to the optical wavelengths. Surprisingly, implementing multidimensional spectroscopy in the THz frequency spectral region has lagged the optical domain, despite the longer wavelengths reducing the impact of phase fluctuations. The challenge in the THz regime has been the poor detection methods, resulting in very long averaging times being needed. Gao et al. solved this challenge by implementing a very clever parallel detection method using a combination of a reflective echelon, a birefringent prism and a CMOS camera. The echelon produces a sampling pulse with delay that varies spatially, which is then captured with the camera to produce a full temporal trace of many relative delays from a single shot, rather requiring one shot per pulse. A practical approach to THz multidimensional spectroscopy can broaden its impact to many condensed matter systems as well as molecular rotational transitions.

---

---

 Add Comment

You must log in to add comments.