The resolution of traditional optical microscopes is limited to approximately half the wavelength of light. This Major Research Instrumentation project acquires a state-of-the-art, scanning near-field optical microscope that enables the optical investigation of nanomaterials cooled to liquid-helium temperature and mapping of chemical composition at more than ten times this spatial resolution. The microscope operates by focusing a light source onto a metallized tip and enhancing the local electric field by plasmonic excitation. The microscope detects the backscattered light as a function of position to map the optical properties of the sample. The unique instrument capabilities help to establish the University of Arizona as a regional and national hub for the optical characterization of materials that is broadly accessible to users from throughout the United States. The addition of the microscope provides cutting-edge student training, education, and workforce development opportunities and leads to advances in physics, materials science, photonics, life sciences, and planetary sciences. The instrument is also showcased in an annual workshop in conjunction with the spring Materials Research Society meeting in Phoenix, and used in an annual summer training course on scanning probe microscopy for students and other early-career researchers, many of whom come from underrepresented groups in science and engineering. The scanning near-field optical microscope complements a suite of multiuser systems at the University of Arizona for the characterization of nanomaterials over a large spatial and energy scale.
The scanning near-field optical microscope has several unique features such as the ability to reach temperatures less than 10 K, to perform spatially resolved Fourier transform infrared spectroscopy with sub-wavelength resolution, to perform near-field mapping using both visible and near-infrared sources, and to perform tip-enhanced photoluminescence measurements. The microscope supports a broad range of research projects, including: (1) excitons and defects in atomically thin materials; (2) plasmonics in carbon nanotubes; (3) degradation processes in organic semiconductors; (4) magneto-optical polymers for magnetic field imaging; (5) nanoparticles for drug delivery; and (6) the composition of meteorites. For all of these projects, the ability to probe the optical response of the materials at the sub-wavelength scale is essential to advance knowledge for materials research and development, and to explore new applications that benefit the society.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
