Single-molecule optical absorption imaging by nanomechanical photothermal sensing at room temperature

Abstract

Absorption microscopy is a powerful technique, enabling the detection of single non- fluorescent molecules at room temperature. So far, the molecular absorption has been probed optically via the attenuation of a probing laser. The sensitivity of optical probing is not only restricted by background scattering, but it is fundamentally limited by laser shot noise. Here, we present nanomechanical photothermal microscopy, which overcomes the scattering and shot noise limit by detecting the sample absorption directly with a temperature sensitive substrate. We use nanomechanical silicon nitride drums, whose resonant frequency detunes with local heating. Individual Au nanoparticles with diameters from 10 nm - 200 nm and single molecules (Atto 633) are scanned with a 305 μW heating laser with a peak irradiance of 330 μW/μm2. Using stress-optimized drums, we achieve a sensitivity of 45 fW/sqrt(Hz), which results in a signal-to-noise ratio of >60 for a single molecule. Our method has important consequences for a wide range of applications, such as imaging, absorption analysis and spectrochemical analysis of non-fluorescent samples.

References in corpus (6)

• Photothermal heterodyne imaging of individual nonfluorescent nanoclusters and nanocrystals
• Single metallic nanoparticle imaging for protein detection in cells
• Frequency fluctuations in silicon nanoresonators
• The thermal conductivity of silicon nitride membranes is not sensitive to stress
• Effect of oxygen plasma on nanomechanical silicon nitride resonators
• Quantitative and Qualitative Study of Gaussian Beam Visualization Techniques

Cited by in corpus (20)

• Mesoscopic physics of nanomechanical systems
• Nanomechanical Dissipation and Strain Engineering
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• Single 5-nm quantum dot detection via microtoroid optical resonator photothermal microscopy
• Modelling and observation of nonlinear damping in dissipation-diluted nanomechanical resonators
• Thermal radiation dominated heat transfer in nanomechanical silicon nitride drum resonators
• Resonantly induced friction in driven nanomechanical systems
• Thermal transport and frequency response of localized modes on low-stress nanomechanical silicon nitride drums featuring a phononic bandgap structure
• Nanomechanical spectroscopy of 2D materials
• Analysis of carbon content in direct-write plasmonic Au structures by nanomechanical scanning absorption microscopy
• Sub-ppm Nanomechanical Absorption Spectroscopy of Silicon Nitride
• Silicon cantilevers locally heated from 300K up to the melting point: temperature profile measurement from their resonances frequency shift
• Gain-assisted critical coupling for enhanced optical absorption in graphene
• Nanomechanical Photothermal Near Infrared Spectromicroscopy of Individual Nanorods
• Low-Dissipation Nanomechanical Devices from Monocrystalline Silicon Carbide
• Thermo-optical bistability in silicon micro-cantilevers
• Directional emission in an on-chip acoustic waveguide
• A practical model of twin-beam experiments for sub-shot-noise absorption measurements
• On-Chip Frequency Noise Cancellation in Nanomechanical Resonators using Cavity Optomechanics
• Mechanical dissipation by substrate-mode coupling in SiN resonators