Coherent two-dimensional terahertz-terahertz-Raman spectroscopy.
We present 2D terahertz-terahertz-Raman (2D TTR) spectroscopy, the first technique, to our knowledge, to interrogate a liquid with multiple pulses of terahertz (THz) light. This hybrid approach isolates nonlinear signatures in isotropic media, and is sensitive to the coupling and anharmonicity of thermally activated THz modes that play a central role in liquid-phase chemistry. Specifically, by varying the timing between two intense THz pulses, we control the orientational alignment of molecules in a liquid, and nonlinearly excite vibrational coherences. A comparison of experimental and simulated 2D TTR spectra of bromoform (CHBr3), carbon tetrachloride (CCl4), and dibromodichloromethane (CBr2Cl2) shows previously unobserved off-diagonal anharmonic coupling between thermally populated vibrational modes.
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125;
Ian A
IA
Finneran
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125;
Ralph
R
Welsch
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125;
Marco A
MA
Allodi
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125;
Thomas F
TF
Miller
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 gab@gps.caltech.edu.
Geoffrey A
GA
Blake
coherent multidimensional spectroscopy; terahertz; ultrafast dynamics