Nanowerk December 13, 2023
Despite its prevalence, the photothermal effect in light-absorbing nanoparticles has typically been assessed using bulk measurements, neglecting near-field effects. Beyond standard imaging and therapeutic uses, nanosecond-transient photothermal effects have been harnessed for bacterial inactivation, neural stimulation, drug delivery, and chemical synthesis. While scanning probe microscopy and electron microscopy offer single-particle imaging of photothermal fields, their slow speed limits observations to milliseconds or seconds, preventing nanoscale dynamic investigations. Researchers at the University of Illinois Urbana-Champaign introduced decoupled optical force nanoscopy (Dofn), enabling nanometer-scale mapping of photothermal forces by exploiting unique phase responses to temporal modulation. They employed the photothermal effect’s back-action to distinguish various time frames within a modulation period. This allowed them to capture the dynamic photothermal process of a single gold nanorod in the nanosecond range, providing insights into non-stationary thermal diffusion at the nanoscale… read more. Open Access TECHNICAL ARTICLE
Operational schematics of decoupled optical force nanoscopy (Dofn). Credit: Nature Communications volume 14, Article number: 7267 (2023)Â