The design of the environment chamber that will house the entire system has been made and construction will be finished by July 2020. A highly reproducible methodology was made to (1) make the probe mount, (2) mount the Au tip and (3) recycle the probe mount once the Au tip is not usable. The head was able to approach and scan the surface of a chromium standard test sample (an array of square pits) using a tungsten tip as a test tip. The scanning probe head design has also been finalized and a home-made prototype scanning probe head has been successfully made. To make the probe, a protocol was developed to electrochemically etch Au wires (diameter = 100 microns) to make a sharp Au probe (diameter ~ 32 nm). These simulations consider two kinds of environment for the sample: (1) the sample is dry and exposed to air and (2) the sample is in a liquid environment. I have also conducted FDTD simulations to optimize the best shape and position of the Au probe that would give the highest amount of tip-enhancement and therefore, the highest signal from the sample. The necessary components were bought and assembled into the system. Through theoretical calculations done via FDTD simulations and electromagnetic field analysis using Mathematica, I determined the optimum field distribution needed to illuminate the sample and the specifications of the optics needed to generate this field. I have been able to finalize the designs of both the illumination and the detection optical systems.
Nanospectroscopy / Raman spectroscopy / surface science / optics
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