SEMINAR 1. Title : Nanoscale Optical Spectroscopy 2. Speaker : Jungseok Chae (Center for Quantum Nanoscience, Institute of Basic Science) 3. Time : 16:00 – 17:00, Thursday, March 31, 2016 4. Place : e+ Lecture Hall (room 83188), 2nd Research Building, Sungkyunkwan University 5. Summary : Among the efforts to realize the sub-wavelength resolution using optical spectroscopy, photothermal induced resonance technique (PTIR) has been invented and successfully applied to many scientific fields such as chemistry, biology and materials science and plasmonics etc. PTIR combines the lateral resolution of atomic force microscope (AFM) and light absorption spectroscopic capability. In PTIR, tunable pulsed laser is illuminated to the sample and an AFM tip in contact is used to transduce the thermal expansion of the sample induced by the light absorption. PTIR was developed in the mid-IR range to provide label-free composition mapping and material identification at the nanoscale. However, recently PTIR technique was extended to the visible and near-IR spectral range providing optical bandgap mapping. In this talk, I’ll present, as an example, the successful application of PTIR at organometal trihalide perovskite materials measuring methyl ammonium and chlorine ions distributions and the existence of the ferroelastic domains etc. Recently, we used nanofabricated optomechanical resonator force sensors as a substitution for conventional AFM tips to increase the sensitivity of the PTIR signal. Increased force sensitivity enables to measure the PTIR signal at the monolayer of octadecylchlorosilane molecules. and the real time thermal relaxation of the sample and the thermal conductivity at the nanoscale. 6 Background : Education Ph. D in Physics, Seoul National University (2010) M. S. in Physics , Seoul National University (2004) B. S. in Physics , Seoul National University (2002) Work Postdoctoral Research Associate, CNST at NIST, USA (2016) Postdoctoral Research Associate, CNST at NIST, USA (2013) 7. Questions : (☏ 031-299-4115)