Abstract
A commonly accepted picture of the transition dipole structure of colloidal semiconductor quantum dots is the so-called 2D degenerate dipole. Optical transitions in CdSe-ZnS quantum dot occur primarily for the low energy state for which the total spin angular momentum projection axis is J=±1. These transitions involve X+iY and X-iY combinations of the (hole) Bloch functions along the QD “X” and “Y” axis; in a spherical approximation, there are equal dipole strengths along two orthogonal axes in the QD frame resulting in a 2D degenerate dipole. This 2D dipole model has been used by Bawendi et al.[1] in their studies of quantum dot emission properties and Enderlein et al.[2] in their studies of quantum dot radiation patterns, and also provides a useful prototype of the complicated dipole structure for chiral nanosystems. Despite reliance on this model, a definitive study demonstrating the dipole structure of CdSe-ZnS quantum dots has not yet been performed. However, as demonstrated by Efros[3], transitions between the |1Se > z electron state and |1Se3/2 > hole state contain projections along the quantum dot Z-axis. During excitation, this transition is forbidden; however, non-radiative energy transfer can make this transition allowed during emission. This 3rd dipole component can, in principle, produce a noticeable effect in the observed linear polarization anisotropy of the light emitted from the quantum dot and observed interference patterns.
© 2010 Optical Society of America
PDF ArticleMore Like This
L. Zhu, S. Samudrala, N. Stelmakh, and M. Vasilyev
FThAA4 Frontiers in Optics (FiO) 2010
Eric A. McArthur, Adam J. Morris-Cohen, Kathryn E. Knowles, and Emily A. Weiss
LTuA1 Laser Science (LS) 2010
Akhilesh K. Singh, Karol G. Grycznski, Arup Neogi, and Moon Kim
JThE2 Quantum Electronics and Laser Science Conference (CLEO:FS) 2010