PHYS/ASTR Special Seminar: "Exploring Beyond Diffraction Limits: Advances in Multimodal Near-Field Spectroscopy" - Dr. Chih-Feng Wang (Pacific Northwest National Laboratory)

Chih-Feng Wang, Ph.D.

Physicist

Pacific Northwest National Laboratory

MONDAY, March 4, 2024

11:00 AM in Thornton Hall, Blakeslee Room

Title: Exploring Beyond Diffraction Limits: Advances in Multimodal Near-Field Spectroscopy

Abstract:

Peering beyond the constraints of diffraction nondestructively holds profound importance in unraveling the intricate dynamics of light-matter interactions and associated localized phenomena at the nanoscale. Near-field techniques have been developed to confront this challenge head-on. Among these techniques, tip-enhanced Raman spectroscopy (TERS) stands out, offering unparalleled nanometer-scale spatial resolution to probe the vibrational modes of molecules, thereby revealing their unique chemical fingerprints. While TERS effectively breaches the diffraction barrier, we are also exploring additional possibilities within the realm of near-field techniques under ambient conditions. Our innovative approach involves harnessing scattered photons from the tip as a novel light source in our home-built multimodal nanoscope. This enables us to conduct spatially and spectrally resolved investigations across diverse spectroscopic modalities. Consequently, we extend optical nano-imaging capabilities to linear and nonlinear optical responses in materials, including single-photon and two-photon photoluminescence, nano-extinction, second harmonic generation, four-wave mixing, and more, all achieved with ultrahigh spatial resolution. In this seminar, I will present the know-how in multimodal hyperspectral nanoscopy, showcasing its potential to study diverse material properties and phenomena at the nanoscale.