Resolving the emission transition dipole moments of single doubly-excited seeded nanorods via heralded defocused imaging

• DOI: 10.48550/arxiv.2301.07211
• Publication Date: 2023-01-01
• Authors: Daniel Amgar; Gur Lubin; Gaoling Yang; Freddy T. Rabouw; Dan Oron
• Keywords: Biexciton; Nanorod

Semiconductor nanocrystal emission polarization is a crucial probe of physics and an essential factor for nanocrystal-based technologies. While the transition dipole moment lowest excited state to ground well characterized, higher multiexcitonic transitions inaccessible via most spectroscopy techniques. Here, we realize direct characterization doubly-excited relaxation by heralded defocused imaging. Defocused imaging maps pattern onto fast single-photon avalanche diode detector array, allowing post-selection photon pairs emitted from biexciton-exciton cascade resolving differences in moments. Type-I1/2 seeded nanorods exhibit anisotropy biexciton-to-exciton compared exciton-to-ground transition. In contrast, type-II display reduction biexciton anisotropy. These findings are rationalized terms interplay between transient dynamics refractive index excitonic fine structure.