Low-temperature coherence-time measurements for CdSe colloidal nanocrystals emission

In this paper, precise measurement of the time coherence of CdSe nanocrystals fluorescence is reported. At low temperature, where emission linewidth is expected to be below 0.2 meV, direct linewidth measurements are not possible, due to insufficient spectrometer resolution and spectral diffusion of the emission wavelength. To obtain a higher resolution, Michelson interferometer is used. An original highly sensitive method, based on the time-correlation between the photons detected at the two interferometer outputs is developed.