Graduate Student Haomin Wang

POSTPONED

"Infrared Nanospectroscopy Enabled by an Atomic Force Microscopy Probe" 

Abbe’s diffraction limit sets the highest resolving power of an optical microscope to be half the wavelength of light, which spans from hundreds of nanometers to several microns for visible and infrared light.[1] To improve the spatial resolution beyond the diffraction limit, a nanoscale probe is used to confine the light field into a small volume that is comparable to the probe scale, through the well-known gap-mode enhancing effect.[2] In this work, two infrared nanospectroscopic methods are introduced: Peak force scattering-type near-field optical microscopy (PF-SNOM) and liquid-phase peak force infrared microscopy (LiPFIR). Both methods adopt a probe used in an atomic force microscope to achieve nanoscale confinement. The PF-SNOM and LiPFIR methods use different ways to deliver light into the probe-sample region and have different detection schemes, which makes each technique capable of conducting unique studies: PF-SNOM can map the light field of a nanostructure in 3D space, while LiPFIR is suitable for detecting chemical changes in liquid phases. Both methods deliver a super-resolution of ~10 nm, which significantly exceeds the infrared diffraction limit. The PF-SNOM and LiPFIR methods open doors for explorations within nanoplasmonics, biological phenomena and chemical reactions.

References:
[1] Abbe, E. Beiträge zur Theorie des Mikroskops und der mikroskopischen Wahrnehmung. Arch. Mikrosk. Anat. 9, 413–418 (1873).
[2] Novotny, L. & Hecht, B. Principles of Nano-Optics (Cambridge University Press, Cambridge, 2012).