The group led by Professor Hiroaki Misawa (Okayama Univ.), Associate Professor Tomoya Oshikiri (Planned research B02, Tohoku Univ.) and Professor Keiji Sasaki (Advisor, Hokkaido Univ.), has developed a substrate that enables highly sensitive and spatially uniform surface-enhanced Raman scattering (SERS). This substrate comprises densely packed gold nanoparticles (d-AuNPs)/titanium dioxide/Au film (d-ATA). d-ATA exhibits a significant enhancement of the near-field intensity, resulting in a 78-fold increase in the SERS signal for crystal violet (CV) due to the ultrastrong optical coupling between d-AuNPs and Fabry–Pérot nanocavities. Importantly, high sensitivity and a spatially uniform signal intensity can be obtained without precise control of the shape and arrangement of the nanoscale AuNPs, enabling quantitative SERS measurements. These findings suggest that the SERS signal under modal ultrastrong coupling originates from multiple plasmonic particles with quantum coherence.
This research was published in the academic journal “ACS Nano” on February 1st, 2024.

https://pubs.acs.org/doi/full/10.1021/acsnano.3c10959