Near-Field Nanoprobing Using Si Tip-Au Nanoparticle Photoinduced Force Microscopy with 120:1 Signal-to-Noise Ratio, Sub-6-nm Resolution

Abstract

A nanoscopy technique that can characterize light-matter interactions with ever increasing spatial resolution and signal-to-noise ratio (SNR) is desired for spectroscopy at molecular levels. Photoinduced force microscopy (PiFM) with Au-coated probe-tips has been demonstrated as an excellent solution for this purpose. However, its accuracy is limited by the asymmetric shape of the Au-coated tip resulting in tip-induced anisotropy. To overcome such deficiencies, we propose a Si tip-Au nanoparticle (NP) combination in PiFM. We map the near-field distribution of the Au NPs in various arrangements with an unprecedented SNR of up to 120, a more than 10-fold improvement compared to conventional optical near-field techniques, and a spatial resolution down to 5.8 nm, smaller than 1/100 of the wavelength, even surpassing the tip-curvature limitation. We also map the beam profile of an azimuthally polarized beam (APB) with an excellent symmetry. The proposed approach can lead to the promising single molecule spectroscopy.

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• Unscrambling Structured Chirality with Structured Light at Nanoscale Using Photo-induced Force
• Theoretical Analysis of Optically Selective Imaging in Photoinduced Force Microscopy
• Helicity Maximization of Structured Light to Empower Nanoscale Chiral Matter Interaction
• Helicity Maximization Below the Diffraction Limit
• Excitonic Wave Function Reconstruction from Near-Field Spectra Using Machine Learning Techniques
• Two-scale structure for giant field enhancement: combination of Rayleigh anomaly and colloidal plasmonic resonance
• Far-field intensity signature of sub-wavelength microscopic objects
• Photoinduced Magnetic Force Microscopy: Enabling Direct and Exclusive Detection of Optical Magnetism