STARK SPECTROSCOPY OF CDSE NANOCRYSTALLITES - THE SIGNIFICANCE OF TRANSITION LINEWIDTHS

We use Stark spectroscopy to examine the nature of the excited states of CdSe nanocrystallites. The Stark spectra we obtain are in the small coupling limit in which the changes induced by the electric field to the absorption spectrum are small compared to the transition linewidth s. Within this limit, we theoretically examine the dependence of the l ine shape of Stark difference spectra on the linewidth of the transiti ons involved. For systems such as CdSe nanocrystallites, which have ov erlapping transitions coupled by the electric field, we find that the usual association of derivatives of absorption features with dipole mo ments and polarizabilities is problematic. We show that the Stark abso rption spectrum of the CdSe nanocrystallites can be explained by polar izable and delocalized nonpolar excited states. (C) 1995 American Inst itute of Physics.