10.1021/jp404713x.s001 Erin S. Boyle Erin S. Boyle Andrei V. Pakoulev Andrei V. Pakoulev John C. Wright John C. Wright Fully Coherent Triple Sum Frequency Spectroscopy of a Benzene Fermi Resonance American Chemical Society 2013 output beam Benzene Fermi ResonanceIn vibrational resonances technique probe states Triple Sum Frequency Raman transition ω2 pulses τ31 delay times coherence pathway τ21 ω1 Coherent Triple Sum Frequency Spectroscopy ω2 axes parity selection rules time orderings frequency excitation pulses ω3 pulse model system TSF CMDS excitation pulses 2013-07-11 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Fully_Coherent_Triple_Sum_Frequency_Spectroscopy_of_a_Benzene_Fermi_Resonance/2396857 In this paper we present a new multiresonant coherent multidimensional spectroscopy (CMDS) technique employing a pathway that is both fully coherent and necessarily unique. This technique is based on a Triple Sum Frequency (TSF) coherence pathway with three excitation pulses having frequencies ω<sub>1</sub>, ω<sub>2</sub>, and ω<sub>3</sub> and the phase matching condition <i>k⃗</i><sub>1</sub> + <i>k⃗</i><sub>2</sub> + <i>k⃗</i><sub>3</sub>. Two-dimensional spectra are created by independently tuning the ω<sub>1</sub> and ω<sub>2</sub> pulses across vibrational resonances while monitoring the intensity of a visible output beam created by a Raman transition induced by the ω<sub>3</sub> pulse. Two-dimensional plots of the coherent dynamics are created by independently scanning the τ<sub>21</sub> and τ<sub>31</sub> delay times between the different frequency excitation pulses over all time orderings. TSF CMDS separates fundamental and overtone/combination band states uniquely onto the ω<sub>1</sub> and ω<sub>2</sub> axes when τ<sub>21</sub> ≠ 0. TSF is valuable in its ability to probe states of complementary parity to those seen in Doubly Vibrationally Enhanced Four-Wave Mixing (DOVE-FWM), the other fully coherent mixed electronic/vibrational CMDS method. This capability is demonstrated through the use of neat benzene as a model system, where the center of inversion imposes strict parity selection rules.