NIST PTIR Instrumentation and Capabilities

Photothermal induced resonance (PTIR) combines the spatial resolution of atomic force microscopy (AFM) with the specificity of absorption spectroscopy, providing information, in the mid-IR, on the chemical composition and molecular conformation, and, in the visible-nIR, on the bandgap and defects with a wavelength independent spatial resolution (≈ 10 - 20 nm). NIST PTIR instrument consist of 2 modified AFM microscopes and 6 wavelengths-tunable, pulsed lasers covering the spectral range from 405 nm to 16000 nm, continuously. Additionally, custom-made nanoscale optomechanical AFM probes developed at NIST enable capturing the thermalization dynamic of the sample in PTIR experiments with 10 ns temporal resolution, yielding chemical composition and the thermal conductivity at the nanoscale concurrently. We recently demonstrated comparable PTIR SNR and lateral resolution in air and water. The instrument is also interfaced with custom electronics to perform time resolved SThM and SJEM experiments.

Current efforts are directed to extend PTIR operation in UHV and cryogenic temperature (down to 5K) as well as implementing other scan probe techniques such as STM-EL, STM-PL, TERS at cryogenic temperatures.