Scattering-scanning nearfield optical microscopy (s-SNOM) is a technique that combines an atomic force microscope (AFM) cantilever and Fourier-transform infrared (FTIR) spectroscopy to produce localized (~10 nm) IR spectra within a bulk sample. The goal of my project is to build a user facility which allows people to use this technique as a means to study vibrational/structural information with spatial resolutions that are sub-diffraction limited. The interaction of the cantilever combined with an incident electric field provides a change in polarizability and enhancement of the near field that corresponds to  a change in phase and amplitude localized to where the tip is interacting with the sample. The scattered signal is then combined with a reference beam which undergoes a constant change in position (and in turn phase) in a Michelson-type interferometer, allowing measurement of the near field signal that is sufficiently separated from the background of the sample. Though this technique is commercially available, it is typically confined to a single excitation wavelength and is typically used with continuous wave lasers, which does not allow dynamic processes within materials at nanometer length scales to be measured with wavelength tunable light. The instrument that I am building uses an ultrafast 1MHz laser which is tunable in wavelength from the visible to mid-infrared range. Dimanganese decacarbonyl has been examined using FTIR and vibrational pump-probe spectrocopy at different time delays to show success of the interferometry and time resolved portions of the s-SNOM instrument. Integration of the AFM and its relevant challenges during the building of this project will be presented.

Combining s-SNOM and ultrafast spectroscopy for high spatial and temporal resolution microscopy as a user facility instrument

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.