Exciton transitions in tetrapod-shaped CdTe nanocrystals investigated by photomodulated transmittance spectroscopy

The excitonic nature of the optical transitions in tetrapod-shaped colloidal CdTe nanocrystals is assessed by means of photomodulated transmittance spectroscopy. The line-shape analysis of the photomodulation transmittance spectra indicates the photoinduced Stark effect as the dominant modulation mechanism, and the presence of excitonic transitions even at room temperature, with an exciton binding energy of about 25 meV, larger than the bulk value. (c) 2006 American Institute of Physics.