Fig. 3
Thermally driven radiation of intrinsic semiconducting nanotubes. a Optical image of the light emission from the nanotubes at 2100 K. The gray vertical and white horizontal dotted lines indicate the positions of the nanotube and slit edges, respectively. The scale bar is 5 μm. b The polarization dependence of the emission intensities of the nanotube at 1470 K. The polarization is parallel to the nanotube axis at 0°. The dotted curve is a cos2 fit. c The light emission spectrum of the (18,8) nanotube at 1470 K. The red dotted curve is a guide to the eye (see Spectral analyses in Methods). In the inset, the same spectrum is replotted as a function of wavelength. The gray dotted curves indicate blackbody radiation at 1470 K. The peak intensity of the nanotube’s emission is normalized to the blackbody radiation curve. The asterisks indicate the G-mode. d Linear-log plot of the emission intensities integrated over 0.8–1.2 eV as a function of the inverse temperature (1/kBT). The solid line is the fitting result based on the Boltzmann statistics described as exp(−E/kBT), with E = 0.80 eV. The inset shows the dependence of the emission intensities on the continuous-wave laser intensity (Iex)
