Spectroscopic properties unique to nano-emitters.

The spectral position of light emission from an individual carbon nanotube is shown to depend on the location of the nanotube within the focal spot, while no such effect is present for macroscopic emitters. In addition, in contrast to macroscopic emitters, the measured line width from the nanotube emitter is independent of spectrometer entrance slit width. The effects are general for any nanoscale optical emitter with at least one dimension smaller than the optical diffraction limit.