Correlated electronic and vibrational motions play an important role in ultrafast photoinduced processes in chemistry, biology and material science. A molecular level description of ultrafast photoinduced processes relies on developing direct experimental probes of the interplay of electonic, vibrational/atomic degrees of freedom. Cyanide bridged transition metal mixed valence complexes provide a rich playground for exploring the coupling between electronic and vibrational motions. I will describe the use two-dimensional (2D) IR spectroscopy to determine the anharmonic couplings and angles between the transition dipole moments of the four cyanide stretching vibrations in [(NH3)5RuIIINCFeII(CN)5]− (FeRu) and [(NC)5FeIICNPtIV(NH3)4NCFeII(CN)5]4− (FePtFe). Our results reveal the important role of the solvent in modulating the molecular geometry, the anharmonic couplings and the vibrational relaxation among the four coupled cyanide stretching vibrations in the ground electronic state. Next, the talk will focus on developing 2D Fourier Transform vibrational-electronic (2D -VE) spectroscopy to directly probe the couplings between the high frequency cyanide stretching modes and the metal-to-metal charge transfer transition (MMCT). A third order IR-IR-Visible pulse sequence resulting in a 2D plot with a vibrational (IR) excitation axis and an electronic (visible/NIR) detection axis displays cross-peaks between the cyanide stretching vibrations and the MMCT process. The implications and potential applications of this new measurement will be discussed.

Directly correlating electronic and vibrational motions with multidimensional coherent spectroscopies

249th National Meeting (2015)

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