报告时间:2017年12月30日(周六)上午10:30
报告地点:高等研究院会议室
报告人:陶冶
任 职:哈佛大学,Rowland Fellow, Principle Investigator
题 目:Toward a 3-dimensional atomic resolution microscope
报告简介:
Nanotechnology has come of age to blur the boundary between the pure sciences and traditional engineering. At face value, the miniaturization of top-down devices and the bottom-up manufacturing of nanoscale engineering materials have since long overlapped across length scales, specifically in the low nanometer range (100-102 nm). However, true convergence, or atomic- and molecular-precision in the manufacturing of individual pieces of nanomaterials and of their 3-dimensional assemblies, remains a lofty dream. The majority of engineering and biomedically-relevant nanomaterials (including disease agents) will continue to remain structurally heterogeneous well into the foreseeable decades.
The heterogeneity in nanoscale matter presents challenges. Structural heterogeneity translates into stochasticity in device properties. The absence of a tool to non-destructively capture the atomic structure of an arbitrary, individual speck of matter with 3 dimensional spatial and chemical resolution hinders understanding of structure-activity relationship governing the 100-102 nm length scale. And the lack of such understanding impedes the advent of better device uniformity and performance. The heterogeneity also offers opportunities. Magnetic resonance force microscopy (MRFM) is a hybrid between atomic force microscopy and magnetic resonance imaging poised to become such a tool.
In this talk, I will draw examples from recent developments in MRFM to illustrate the urgency to obtain atomic-level structural information in developing better nanoscale technologies, notably those for MRFM itself. I will focus on efforts to improve the sensitivity of force sensors to illustrate its subtle dependence on surface chemical states at levels well below a monolayer in coverage, and in bulk impurity levels below parts per million.Certain data even suggest that a few atomic defects can completely determine the mechanical sensitivity of a macroscopic micromechanical resonator, hundreds of microns in size.The resulting recognition of empirical structure-property correlations has culminated in a wafer-scale devices capable of measuring forces from single nuclear spins. MRFM has thus reached a major milestone in its journey towards becoming the ultimate atomic structure microscope.