Raman spectroscopy of two-dimensional materials

Venue: Room 201, Teaching Building 12, Yuquan Campus

Speaker: Riichiro Saito, Professor of Physics, Department of Physics, Tohoku University

Abstract

We overview our recent theoretical activity on Raman spectroscopy of two-dimensional materials. Raman scattering is an inelastic scattering of light. Raman spectroscopy is frequently observed for characterizing the structure of emerging two-dimensional materials such as graphene, transition metal dichalcogenides. When we change the laser excitation energy for observing the Raman spectra, the Raman intensity significantly changes due to the resonant Raman effect. Combining with our original computer program for resonant Raman intensity, we can understand many properties from Raman spectra of the recent two-dimensional materials. In particular, when we use circularly polarized light, we get some special Raman spectra appears in which the inelastic scattered light has an opposite helicity of the circularly polarized light to that of the incident light, which we can explain by the symmetry analysis. Here we will discuss on conservation law of angular momentum of a photon in the Raman processes. When we discuss optical properties of two-dimensional materials, the concepts of valley polarization and circular dichroism are important, which we will discuss possible phenomena that occur in two-dimensional materials.

Short biography

Riichiro Saito was born in 1958, and received his Ph. D. at the University of Tokyo in 1985. He became Research Associate at The University of Tokyo (1985), Associate Professor at The University of Electro-Communications (1990), and Professor at Department of Physics, Tohoku University (2003). He has been a visiting scientist at Massachusetts Institute of Technology (1991-2) at Prof. Gene Dresselhaus and Prof. Mildred S. Dresselhaus, Visiting Associate Professor at The University of Tokyo (1990-1, 1993-4, 1997-8), Visiting Professor at Shanghai University (2009.10-2011.10) and Zhejiang University (2018.12-).

His main field of research is “Physical Properties of Carbon Nanotubes” and “Raman spectroscopy in Graphite Related Systems”. The books with the same titles published, respectively, from Imperial College Press (1998) (CI = 9634) with Prof. Gene Dresselhaus and Prof. Mildred S. Dresselhaus and from Wiley-VCH with Prof. A. Jorio, Prof. Gene Dresselhaus and Prof. Mildred S. Dresselhaus. Recently he is interested in optical properties of two dimensional materials. He got 13th Japan IBM prize (Physics, 1999), Hsun Lee research Award (2006), The Japan Carbon Award for Innovation Research (2008).SomiyaAward, International Union of Materials Research Societies (2009).

He has published 329 original papers with total citation is 31,276(average citation per article = 95.06, h-index=80). 62 papers are more than 100 citations and among them 28 papers are more than 200. Google scholar citation index is 56,902.