Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 77: Gerhard Ertl Young Investigator Award

O 77.3: Invited Talk

Thursday, March 10, 2016, 11:30–12:00, S051

Direct observation of H-bond dynamics using scanning tunneling microscopy — •Takashi Kumagai — Fritz-Haber Institute

H-bond dynamics is involved in many important processes in chemistry and biology. However, it is still poorly understood at the microscopic level because the dynamics, H-bond rearrangement and H-atom (proton) transfer, remains difficult to directly probe at the single-molecule level. Additionally, quantum nuclear effects, like tunneling and zero-point energy, play a crucial role due to the small mass of the H atom, which could cause difficultly in accurately describing the H-bond dynamics. We have used low-temperature STM to directly observe the H-bond dynamics, which were examined with a variety of models assembled from single atoms/molecules by STM manipulation [1-8].

I will discuss the direct observation of several different types of H-bond dynamics; 1) the H-bond exchange reaction governed by tunneling in a water dimer [1], 2) vibrationally-induced H-atom relay reactions in one-dimensional H-bonded water-hydroxyl complexes [4], and 3) the intramolecular H-atom transfer (tautomerization) in a porphycene molecule [6,7]. These results provide a novel insight into H-bond dynamics at the single-molecule level and unveiled the impact of the local environments on the process that is hidden in studies of molecular ensembles probed by spatially-averaging spectroscopies [8].

References; [1] PRL 100, 166101. [2] PRB 79, 035423. [3] PRB 81, 045402. [4] Nat. Mater. 11, 167. [5] Visualization of hydrogen-bond dynamics, Springer (2012). [6] PRL 111, 246101. [7] Nat. Chem. 6, 41. [8] Prog. Surf. Sci. 90, 239.