Related Experiment Video
Updated: Feb 12, 2026

Optical Trapping of Nanoparticles
Published on: January 15, 2013
Unveiling hole trapping and surface dynamics of NiO nanoparticles
Luca D'Amario1, Jens Föhlinger1, Gerrit Boschloo1
1Department of Chemistry - Ångström Laboratory , Uppsala University , Box 523 , 751 20 Uppsala , Sweden . Email: leif.hammarstrom@kemi.uu.se ; ; Tel: +46 18 471 3648.
Abstract:
The research effort in mesoporous p-type semiconductors is increasing due to their potential application in photoelectrochemical energy conversion devices. In this paper an electron-hole pair is created by band-gap excitation of NiO nanoparticles and the dynamics of the electron and the hole is followed until their recombination. By spectroscopic characterization it was found that surface Ni3+ states work as traps for both electrons and holes. The trapped electron was assigned to a Ni2+ state and the trapped hole to a "Ni4+" state positioned close to the valence band edge. The recombination kinetics of these traps was studied and related with the concept of hole relaxation suggested before. The time scale of the hole relaxation was found to be in the order of tens of ns. Finally the spectroscopic evidence of this relaxation is presented in a sensitized film.
Related Concept Videos
Social Traps
Detection of Black Holes
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
Dynamic Equilibrium
Surface Tension and Surface Energy
Consider a beaker filled with liquid. The bulk molecules in the liquid experience equal attractive forces on all sides with the surrounding molecules. However, the surface molecules experience a net attractive force downward due to the bulk molecules. The surface of the liquid behaves like a stretched membrane,...
Wood Surfacing
The equipment used in the surfacing process is a plane equipped with rotating blades. This tool efficiently smoothens the wood surface and can...
Cell-surface Signaling

