"Single molecule spectroscopy using STM" Prof. Maki Kawai

Title: Single molecule spectroscopy using STM Speaker: Prof. maki Kawai, Department of Advanced Materials Scinece, The Univeristy of Tokyo, Kashiwa, Japan Abstract: STM is a useful tool for spectroscopy utilizing its ultimate spatial resolution. STS including inelastic electron tunneling spectroscopy (IETS) is not only applied to the static spectroscopy but also reflects dynamical phenomena as motion or reaction of molecules induced by the excitation of molecular states, and is utilized to identify the quantum states of the materials. Dynamical information includes as how molecular vibrations can couple with the relevant dynamical processes et al [1]. At the conference I will present some typical examples of how the fundamental excitation of vibration modes are coupled to chemical reactions at surfaces. Inelastic electron tunneling spectroscopy (IETS) is widely used to identify the electronic states and is especially useful when the molecule is in contact with solid surfaces. Utilizing the tunneling feature of electron as Multiple Andreev reflection caused between superconductor electrodes, we have recently succeeded to unveil the electron transfer channels though a molecule sandwiched within superconducting metals [2]. Spin state of the molecule is one of the examples, where it depends on the strength of the coupling between the molecule and substrate. With strong coupling with Cu(110) the spin of FePc is completely killed whereas if decoupled as on Cu(110) 2x1-O, spin survives with change in the direction of easy axis [3]. On Au, weak coupling leads to appearance of Kondo state, where a competition between the RKKY interaction affects the spin state [4]. Kondo state of FePc on Au depends on the adsorption site, where the difference was originating from the coupling with the substrate electrons [5]. References : [1] Y. Kim, et al., Progress in Surface Science, 90 (2015) 85-143, and the references within. [2] Ryoichi Hiraoka, et al., Phys. Rev. B 90 (2014) 241405(R). [3] N. Tsukahara, et al., Phys. Rev. Lett. 102 (2009) 167203. [4] N. Tsukahara, et al., Phys. Rev. Lett. 106 (2011) 187201. [5] E. Minamitani, et al., Phys. Rev. Lett. 109 (2012) 086602.