Down to Atomic-level Direct Thermal Probing and Energy Transport Characterization

讲座名称: Down to Atomic-level Direct Thermal Probing and Energy Transport Characterization
讲座时间 2017-04-26
讲座地点 东三楼东汽报告厅
讲座人 王信伟


讲座题目:Down to Atomic-level Direct Thermal Probing and Energy Transport Characterization
讲座摘要:Temperature is one of the most important physical parameters for characterizing and understanding thermal transport capacity of materials, looking into the physics behind photon-induced material processing, and unrevealing interface energy exchange/coupling. This talk will cover our new technology development and frontier research on thermal probing based on Raman scattering, a technology traditionally widely used for structure analysis. The Raman-based thermal probing in three areas will be covered. The first one is micro/submicron particle induced near-field effect. This phenomenon has been widely used in surface nanoscale structuring and imaging. For the first time, we have accomplished experimental study on nanoscale mapping of particle-induced thermal, stress, and optical fields under near-field excitation. The mapping provides consistent knowledge of conjugated thermal, stress, and near-field focusing at a 20 nm resolution. This represents a very exciting advance for far-field thermal probing of near-field thermal phenomenon with an ultra-high resolution. Particles as small as 160 nm can be clearly mapped employing this technique. The second area is near-field optical focusing by an atomic force microscope. A thermal probing resolution as small as 5 nm has been achieved. We have undertaken pioneering work on the near-filed thermal response, nonlinear optical absorption, and ballistic heat conduction around a region of a few nm. The third area is interface energy coupling between graphene and a substrate. A spatial resolution as good as 1~2 nm has been achieved. For the first time, we are able to distinguish the temperature difference between two materials a few nm apart. Interface energy, optical, and mechanical couplings will be reported. This provides one of the most advanced knowledge base about the physical behavior of graphene on a substrate. Our most recent advance has achieved energy state-resolved Raman to characterize electron diffusion and interface energy coupling of 2D atomic layer materials. This represents accurate characterization by eliminating the errors of laser absorption calculation and Raman properties temperature coefficient calibration.



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