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Abstract
Triply Vibrationally Enhanced Four-Wave Mixing (TRIVE FWM) is a coherent multidimensional spectroscopic technique developed in the Wright Group at the University of Wisconsin - Madison. It is a mixed frequency/time domain technique, which uses three ultrafast mid-IR excitation pulses to excite coherences between vibrational modes to extract spectral and temporal information from the system. The characteristics of TRIVE FWM were explored in the model organometallic systems tungsten hexacarbonyl [W(CO)6], rhodium(I) dicarbonyl acetlyacetonate (RDC), nickel(0) bis(triphenylphosphine) dicarbonyl, and nickel(0) triphenylphosphine tricarbonyl. These studies determined the general spectral and temporal behavior and information contained within TRIVE experiments, and they also uncovered the ability to resolve quantum beats between nearly degenerate states, observe population transfer events, and to observe coherence transfer events (when a coherence evolves into another coherence without loss of phase information). Next, TRIVE experiments were extended beyond model systems to the C-H stretching and bending modes of the alkanes, octane and dotriacontane. Finally, TRIVE experiments were performed with high power excitation lasers, which took the experiments beyond FWM into high order wave mixing (HOWMix). These experiments probed the ground electronic state carbonyl vibrational potential wells of W(CO)6 and RDC by observing signal generated by four through twelve wave mixing processes. High overtone and combination band states were observed and assigned.
