Fig. 3: AUnet assisted fast nanometer-resolution hyperspectral TERS imaging of a Pd/Au(111) catalyst adsorbed with PIC molecule.

a Bright field image of the sample and the gold tip. The region for TERS imaging (120 nm × 120 nm) is localized underneath the nanoscale-region below the tip. b STM topographic image of sub-monolayer Pd deposited on a Au(111) surface obtained by the gold tip. Scanning direction: from bottom to top. c, d TERS imaging of \({v}_{{CC}}\) band intensity (c) and \({v}_{{NC}}\) peak position (d). (i): raw data of fast imaging with an integration time of 100 ms/pixel. (ii): the denoised image by AUnet. (iii): the long-integration-time imaging with 1 s/pixel. e TERS spectra along the white dashed line in (b). (i): raw data. (ii): the denoised data by AUnet. Inset: the molecular structure of PIC and the vibrational mode of \({v}_{{CC}}\) and \({v}_{{NC}}\). f The profile of \({v}_{{NC}}\) frequency along the white dashed line in (d-ii). g panels i, ii: Zoom-in images of the white rectangles in (c). The spatial resolution of the TERS measurement is estimated to be 6 nm from the AUnet-denoised image (panel iii, see details in supplementary Fig. S12). h Red and blue balls are the pixel intensities along the black dotted lines in (c-ii) and (c-iii), respectively. The dash lines are the fits by a first-order polynomials \((y={Kx}+b)\), in which K denotes the slope of the fitted line.