Applications brief: Nanophotonic Atomic Force Microscope Transducers Enable Chemical Composition and Thermal Conductivity Measurements at the Nanoscale

Key points


  • Thermal conductivity can now be measured simultaneously with chemical composition at the nanoscale in photothermal induced resonance experiments
  • This is achieved using picogram-scale probes integrated with photonic resonators to realize functional AFM detection that achieve high temporal resolution and picometer vertical displacement uncertainty simultaneously
  • This photonic readout for small probes breaks the common trade-off between AFM measurement precision and ability to capture transient events, thus transforming the ability to observe nanoscale dynamics in materials

Key words

AFM | chemical composition | nanoscale dynamics | optomechanical resonators | PTIR | thermal conductivity

Authors

J. Chae, S. An, G. Ramer, V. Stavila, G. Holland, Y. Yoon, A. A. Talin, M. Allendorf V. A. Aksyuk, A. Centrone

Abstract

The atomic force microscope (AFM) offers a rich observation window on the nanoscale, yet many dynamic phenomena are too fast and too weak for direct AFM detection. Integrated cavity-optomechanics is revolutionizing micromechanical sensing; however, it has not yet impacted AFM. Here, we make a groundbreaking advance by fabricating picogram-scale probes integrated with photonic resonators to realize functional AFM detection that achieve high temporal resolution (<10 ns) and picometer vertical displacement uncertainty simultaneously. The ability to capture fast events with high precision is leveraged to measure the thermal conductivity (η), for the first time, concurrently with chemical composition at the nanoscale in photothermal induced resonance experiments. The intrinsic η of metal–organic-framework individual microcrystals, not measurable by macroscale techniques, is obtained with a small measurement uncertainty (8%). The improved sensitivity (50×) increases the measurement throughput 2500-fold and enables chemical composition measurement of molecular monolayer-thin samples. Our paradigm-shifting photonic readout for small probes breaks the common trade-off between AFM measurement precision and ability to capture transient events, thus transforming the ability to observe nanoscale dynamics in materials.

Left: PTIR (1720 and 3030 cm−1 ) composition overlay maps of a PMMA (light blue) and polystyrene (red) particles in epoxy matrix (pink). Right: PTIR spectra of each material.
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