title: Ultrafast N-H vibrational dynamics of cyclic doubly hydrogen-bonded homo- and heterodimers.
abstract: Hydrogen-bonded interfaces are essential structural elements in biology. Furthermore, they can mediate electron transport by coupling the electron to proton transfer within the interface. The specific hydrogen-bonding configuration and strength have a large impact on the proton transfer, which exchanges the hydrogen-bonded donor and acceptor species (i.e., NH...O --> N...HO). Modulations of the hydrogen-bonding environment, such as the hydrogen-bond stretch and twist modes, affect the proton-transfer dynamics. Here, we present transient grating and echo peak shift measurements of the NH stretch vibrations of four doubly hydrogen-bonded cyclic dimers in their electronic ground state. The equilibrium vibrational dynamics exhibit strong coherent modulations that we attribute to coupling of the high-frequency NH vibration to the low-frequency interdimer stretch and twist modes and not to interference between multiple Fermi resonances that dominate the substructure of the linear spectra.
authors.forename: Poul B
authors.initials: PB
authors.lastname: Petersen
authors.forename: Sean T
authors.initials: ST
authors.lastname: Roberts
authors.forename: Krupa
authors.initials: K
authors.lastname: Ramasesha
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Nocera
authors.forename: Andrei
authors.initials: A
authors.lastname: Tokmakoff
mesh_terms: D019281:Dimerization; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D009584:Nitrogen / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors; D014732:Vibration
chemical_list: D006859:Hydrogen; D009584:Nitrogen