Publication

Femtosecond polarization relaxation in CdSe nanocrystals

Majed Chergui, Frank van Mourik, Andreas Tortschanoff, Dino Tonti, Awos Al Salman
2007
Conference Papers

Abstract

We present ultrafast pump-probe studies on chem. prepd. CdSe nanocrystals. Upon pulsed optical excitation we find pronounced oscillations, indicating strong coupling to a LO phonon mode. From the polarization dependence of the signal addnl. information about the very first coherent events of exciton dynamics is obtained. The obsd. anisotropy behavior suggests strongly driven dynamics and rapid coherent motion. [on SciFinder (R)]

Official source

https://infoscience.epfl.ch/entities/publication/9256466e-1474-4e90-a9eb-529cdd71c26c

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Majed Chergui, Frank van Mourik, Andreas Tortschanoff, Dino Tonti, Awos Al Salman
2007
Conference Papers

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/9256466e-1474-4e90-a9eb-529cdd71c26c

About this result

Related concepts (21)

Polarization (physics)

Polarization (also polarisation) is a property of transverse waves which specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. A simple example of a polarized transverse wave is vibrations traveling along a taut string (see image); for example, in a musical instrument like a guitar string. Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string.

Quantum dot

Quantum dots (QDs) – also called semiconductor nanocrystals, are semiconductor particles a few nanometres in size, having optical and electronic properties that differ from those of larger particles as a result of quantum mechanics. They are a central topic in nanotechnology and materials science. When the quantum dots are illuminated by UV light, an electron in the quantum dot can be excited to a state of higher energy. In the case of a semiconducting quantum dot, this process corresponds to the transition of an electron from the valence band to the conductance band.

Exciton

An exciton is a bound state of an electron and an electron hole which are attracted to each other by the electrostatic Coulomb force. It is an electrically neutral quasiparticle that exists in insulators, semiconductors and some liquids. The exciton is regarded as an elementary excitation of condensed matter that can transport energy without transporting net electric charge. An exciton can form when a material absorbs a photon of higher energy than its bandgap. This excites an electron from the valence band into the conduction band.

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Femtosecond polarization relaxation in CdSe nanocrystals

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