Abstract
Excited-state relaxations in molecules are responsible for a redshift of the absorption peak with respect to the emission peak (Franck-Condon shift). The magnitude of this shift in semiconductor quantum dots is still unknown. Here we report first-principle calculations of excited-state relaxations in small (diameter Si nanocrystals, showing that the Franck-Condon shift is surprisingly large for a 2.2-nm-diameter nanocrystal). The physical mechanism responsible for the Stokes shift changes abruptly around nanometer in size, providing a clear demarcation between “molecules” and “nanocrystals.”
- Received 22 November 2002
DOI:https://doi.org/10.1103/PhysRevB.68.033313
©2003 American Physical Society