Fig. 9

TERS investigation of semiconductor to metal transition of CNT. a 3-D AFM image of two carbon nanotubes crossing each other. b TERS map of the G⁺- band intensity, collected in the area marked with the white dashed line in (a). c TERS spectra from points (i)-(iv) at the positions marked in (b). Spectrum at point (i) shows the frequency region where the RBM peak is present. Spectrum at point (ii) shows the G-band, composed of two Lorentzian peaks, corresponding to the G⁻- mode (peak 1) and the G⁺- mode (peak 2). Spectrum at point (iii) and (iv) shows two additional peaks, with asymmetric Fano (peak 3) and Lorentzian (peak 4) line-shape, respectively. d Magnification of the spectra far (point ii) and near (point iv) the junction. Reprinted with permission from reference [12], Copyright 2013 by the American Physical Society