title: Imaging a single quantum dot when it is dark.
abstract: We have succeeded in recording extinction images of individual cadmium selenide quantum dots at ambient condition. This is achieved by optimizing the interference between the light that is coherently scattered from the quantum dot and the reflection of the incident laser beam. The ability to interrogate the dot in the absence of fluorescence has revealed that its extinction cross section diminishes in the photobleached state, but interestingly, it remains unchanged during fluorescence blinking off times. Our methodology makes optical imaging and spectroscopy accessible to the study of ultrasmall nanoscopic objects such as nonfluorescent macromolecules and single emitters with very low quantum efficiencies.
authors.affiliation: Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Kukura
authors.forename: M
authors.initials: M
authors.lastname: Celebrano
authors.forename: A
authors.initials: A
authors.lastname: Renn
authors.forename: V
authors.initials: V
authors.lastname: Sandoghdar
mesh_terms: D000465:Algorithms; D001703:Biophysics / Q000379:methods; D019187:Cadmium Compounds / Q000737:chemistry; D004867:Equipment Design; D046911:Macromolecular Substances / Q000737:chemistry; D008856:Microscopy, Fluorescence / Q000379:methods; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D055095:Optics and Photonics; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D046911:Macromolecular Substances; D018036:Selenium Compounds; C058667:cadmium selenide