11.07.2015 Views

Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.

Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.

Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

arrows indicate the on-time truncation point for four different QDs under thesame excitation intensity at RT. Qualitatively, we can describe and understandthe changes as a result of the interaction between the dynamic dark andbright states modeled earlier. As the excitation intensity or thermal energy isreduced, the hopping rate of the random walker slows down and the timeconstant for the truncation is extended within our experimental time. Surfacemodification in the form of ZnS overcoating also extends the power-lawdistribution for the on times. This surface modification should not change thehopping rate of the random walker but rather changes the Auger scatteringrate. Hence, a mechanism such as photo-assisted ejection of a charge due toAuger ionization [12,26] may be responsible for the on-time truncation effect.Recently, reversible quenching of CdSe QDs was shown due to interactionswith oxygen molecules in the presence of light [34]. Although the single-QCFigure 12 (a) Time trace of a single CdTe QD at room temperature, 125 W/cm 2 .(b) The probability distribution of the on time (z) and off time (4) for CdTe QDsat room temperature. The best-fit line shows a power-law behavior with exponentf 1.6.<strong>Copyright</strong> <strong>2004</strong> <strong>by</strong> <strong>Marcel</strong> <strong>Dekker</strong>, <strong>Inc</strong>. <strong>All</strong> <strong>Rights</strong> <strong>Reserved</strong>.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!