Measurement and assignment of the size-dependent optical spectrum in CdSe quantum dots

TLDR

The study aims to discuss the most likely assignments for the remaining four electronic transitions. The authors employed photoluminescence excitation spectroscopy on CdSe quantum dots sized 12–53 Å to track the size dependence of ten absorption features. Six transitions were confidently assigned, with the n_hS3/2 1 S_e and n_hS1/2 1 S_e transitions dominating half the features, and two strong avoided crossings revealed the critical role of valence‑band structure. © 1996 The American Physical Society.

Abstract

We use photoluminescence excitation to study the electronic spectrum of CdSe quantum dots ranging from \ensuremath{\sim}12 to \ensuremath{\sim}53 \AA{} in radius. We follow the size evolution of ten quantum dot absorption features. Comparison of the spectra with theoretical predictions allows us to confidently assign six of these transitions. We discuss the most likely assignments for the remaining four. We find that the ${\mathit{n}}_{\mathit{hS}3/2}$1${\mathit{S}}_{\mathit{e}}$ and ${\mathit{n}}_{\mathit{hS}1/2}$1${\mathit{S}}_{\mathit{e}}$ transitions dominate the spectra, accounting for half of the observed features. Our size-dependent data exhibit two strong avoided crossings, demonstrating the importance of valence-band structure in the description of the excited states. \textcopyright{} 1996 The American Physical Society.