Abstract by Brittany Knighton
Chemistry and Biochemistry
Simple Two-dimensional Terahertz Measurements and Energy Flow Pathways
Multidimensional spectroscopy techniques are excellent for disentangling complex structural correlations, dynamics, and coupling between different degrees of freedom. Within the past 30 years, multidimensional spectroscopy has also been applied to IR, visible, UV, and Terahertz (THz) measurements, proving immensely informative. Two-dimensional (2D) THz spectroscopy is a useful tool for understanding coherent energy flow on ultrafast time scales. To perform 2D THz measurements, we must have two time-delayed THz pulses. Here we present a simple technique for achieving two IR pump pulses with variable, relative delay as well as some of the profound consequences of such measurements. This is a variation on the THz-pump, transient birefringence probe scheme with the addition of as little as one pellicle beamsplitter and a translation stage. Using these simple methods, 2D THz spectroscopy allows us to distinguish excitation pathways and mode couplings in samples like CdWO4. This coupling information will provide important insight into the complex multi-dimensional potential energy surface and how multiple vibrational coordinates couple together.