Ultrafast nanometric imaging of energy flow within and between single carbon dots.

ABSTRACT: Time- and space-resolved excited states at the individual nanoparticle level provide fundamental insights into heterogeneous energy, electron, and heat flow dynamics. Here, we optically excite carbon dots to image electron-phonon dynamics within single dots and nanoscale thermal transport between two dots. We use a scanning tunneling microscope tip as a detector of the optically excited state, via optical blocking of electron tunneling, to record movies of carrier dynamics in the 0.1-500-ps time range. The excited-state electron density migrates from the bulk to molecular-scale (∼1 nm2) surface defects, followed by heterogeneous relaxation of individual dots to either long-lived fluorescent states or back to the ground state. We also image the coupling of optical phonons in individual carb

SUBMITTER: Nguyen HA 

PROVIDER: S-EPMC7980384 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature