Fast Imaging of Single Molecules and Nanoparticles by Wide-Field Microscopy and Spectrally Resolved Confocal Microscopy

W. G. J. H. M. van Sark, P. L. T. M. Frederix, D. J. van den Heuvel, M. A. H. Asselbergs, I. Senf, H. C. Gerritsen

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The dynamic photophysical behaviour of single Cy5- maleimide molecules and core-shell (CdSe)ZnS quantum dots is compared. To this end a home-built fast and sensitive wide-field microscopy system and a scanning confocal microscope coupled to a spectrograph for spectral imaging are employed. The ability to measure time-resolved spectra of quantum dots is shown to be particularly useful in characterizing single quantum dots. The difference in blinking behaviour of single Cy5-maleimide molecules and (CdSe)ZnS quantum dots can be understood by their physical origin, i.e. the presence of a single ‘dark’ state in case of Cy5 versus a distribution of ‘dark’ states in case of (CdSe)ZnS. This intrinsic difference results in higher probabilities to find a quantum dot in a short-lived (<0.02 s) or long-lived (>0.2 s) state than a Cy5-mal molecule. Moreover, from a comparison to data in the literature, it was found that the lifetime of the ‘off’-state of the Cy5-mal molecule is longer than for the non derivatized Cy5 molecule.
Original languageEnglish
Pages (from-to)291-298
JournalSingle Molecules
Volume1
Issue number4
DOIs
Publication statusPublished - 2000

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