 |
|
Argonne researcher studies what makes quantum dots blink
October 05, 2007In order to learn more about the origins of quantum dot blinking, researchers from the U.S. Department of Energy's Argonne National Laboratory, the University of Chicago and the California Institute of Technology have developed a method to characterize it on faster time scales than have previously been accessed.
Nanocrystals of semiconductor material, also known as quantum dots, are being intensively investigated for applications such as light-emitting diodes, solid-state lighting, lasers, and solar cells. They are also already being applied as fluorescent labels for biological imaging, providing several advantages over the molecular dyes typically used, including a wider range of emitted colors and much greater stability.
Quantum dots have great promise as light-emitting materials, because the wavelength, or color, of light that the quantum dots give off can be very widely tuned simply by changing the size of the nanoparticles. If a single dot is observed under a microscope, it can be seen to randomly switch between bright and dark states. This flickering, or blinking, behavior has been widely studied, and it has been found that a single dot can blink off for times that can vary between microseconds and several minutes. The causes of the blinking, though, remain the subject of intense study.
The methods developed by Matt Pelton of Argonne's Center for Nanoscale Materials and his team of collaborators has revealed a previously unobserved change in the blinking behavior on time scales less than a few microseconds. This observation is consistent with the predictions of a model for quantum-dot blinking previously developed by Nobel Laureate Rudolph Marcus, contributor to this research, and his co-workers. In this model, the blinking is controlled by the random fluctuation of energy levels in the quantum dot relative to the energies of trap states on the surface of the nanocrystal or in the nearby environment.
The results of this research provide new insight into the mechanism of quantum-dot blinking, and should help in the development of methods to control and suppress blinking. Detailed results of this work have been published in a paper in the Proceedings of the National Academy of Sciences.
Argonne's Center for Nanoscale Materials work for this research was funded by the U.S. Department of Energy's Office of Basic Energy Science.
Argonne National Laboratory, a renowned R&D center, brings the world's brightest scientists and engineers together to find exciting and creative new solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America 's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.
Argonne National Laboratory
The methods developed by Matt Pelton of Argonne's Center for Nanoscale Materials and his team of collaborators has revealed a previously unobserved change in the blinking behavior on time scales less than a few microseconds. This observation is consistent with the predictions of a model for quantum-dot blinking previously developed by Nobel Laureate Rudolph Marcus, contributor to this research, and his co-workers. In this model, the blinking is controlled by the random fluctuation of energy levels in the quantum dot relative to the energies of trap states on the surface of the nanocrystal or in the nearby environment.
The results of this research provide new insight into the mechanism of quantum-dot blinking, and should help in the development of methods to control and suppress blinking. Detailed results of this work have been published in a paper in the Proceedings of the National Academy of Sciences.
Argonne's Center for Nanoscale Materials work for this research was funded by the U.S. Department of Energy's Office of Basic Energy Science.
Argonne National Laboratory, a renowned R&D center, brings the world's brightest scientists and engineers together to find exciting and creative new solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America 's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.
Argonne National Laboratory
Quantum Dot Current Events and Quantum Dot News RSSMIT: Better way to harness waste heat
New MIT research points the way to a technology that might make it possible to harvest much of the wasted heat produced by everything from computer processor chips to car engines to electric powerplants, and turn it into usable electricity.
Small nanoparticles bring big improvement to medical imaging
If you're watching the complex processes in a living cell, it is easy to miss something important-especially if you are watching changes that take a long time to unfold and require high-spatial-resolution imaging.
JQI researchers create entangled photons from quantum dots
To exploit the quantum world to the fullest, a key commodity is entanglement-the spooky, distance-defying link that can form between objects such as atoms even when they are completely shielded from one another.
U-M physicists create first atomic-scale map of quantum dots
University of Michigan physicists have created the first atomic-scale maps of quantum dots, a major step toward the goal of producing "designer dots" that can be tailored for specific applications.
New DNA Test Uses Nanotechnology to Find Early Signs of Cancer
Using tiny crystals called quantum dots, Johns Hopkins researchers have developed a highly sensitive test to look for DNA attachments that often are early warning signs of cancer.
2 software tools that improve identification of cancer biomarkers earn certification
The explosive growth of genomic and proteomic data has ushered in a new era of molecular medicine in which cancer detection, diagnosis and treatment are tailored to each individual's molecular profile.
All-in-one nanoparticle: A Swiss Army knife for nanomedicine
Nanoparticles are being developed to perform a wide range of medical uses -- imaging tumors, carrying drugs, delivering pulses of heat. Rather than settling for just one of these, researchers at the University of Washington have combined two nanoparticles in one tiny package.
Singapore scientists synthesize gold to shed light on cells' inner workings
Highly fluorescent gold nanoclusters for sub-cellular imaging have been synthesized by researchers at the Institute of Bioengineering and Nanotechnology (IBN).
McGill researchers squeeze light out of quantum dots
McGill University researchers have successfully amplified light with so-called "colloidal quantum dots," a technology that had been written off by many as a dead-end.
'Strained' quantum dots show new optical properties
Quantum dots, tiny luminescent particles made of semiconductors, hold promise for detecting and treating cancer earlier. However, if doctors were to use them in humans, quantum dots could have limitations related to their size and possible toxicity.
More Quantum Dot Current Events and Quantum Dot News Articles
 |
The Quantum Dot: A Journey into the Future of Microelectronics by Richard Turton (Author) Since first developed in the early sixties, silicon chip technology has made vast leaps forward. From a rudimentary circuit with a mere handful of transistors, the chip has evolved into a technological miracle, packing millions of bits of information on a surface no larger than a human thumbnail. And most experts predict that in the near future, we will see chips with over a billion bits. At the same time, this revolution in microelectronics has sparked a dramatic change in the way we live. An integral part of the computer industry, the microchip is found in everything from lasers, fax machines, and satellites to greeting cards and children's toys. And yet few people have any idea how chips work, or how so much information can be captured in such a miniscule space. Now, in... |
 |
Semiconductor Quantum Dots by Y. Masumoto (Editor), T. Takagahara (Editor) Semiconductor quantum dots represent one of the fields of solid state physics that have experienced the greatest progress in the last decade. Recent years have witnessed the discovery of many striking new aspects of the optical response and electronic transport phenomena. This book surveys this progress in the physics, optical spectroscopy and application-oriented research of semiconductor quantum dots. It focuses especially on excitons, multi-excitons, their dynamical relaxation behaviour and their interactions with the surroundings of a semiconductor quantum dot. Recent developments in fabrication techniques are reviewed and potential applications discussed. This book will serve not only as an introductory textbook for graduate students but also as a concise guide for active researchers. |
 |
Semiconductor Nanocrystal Quantum Dots: Synthesis, Assembly, Spectroscopy and Applications by Andrey Rogach (Editor) This is the first book to specifically focus on semiconductor nanocrystals and address their synthesis and assembly, optical properties and spectroscopy, and potential areas of nanocrystal-based devices including applications in biology and medicine. Nanoscience will transfer into new products and processes in the next two decades. One emerging area where this challenge will be successfully met is the field of semiconductor nanocrystals. Also known as colloidal quantum dots, their unique properties have attracted much attention in the last twenty years. These highly efficient fluorophores have a strong band-gap luminescence tuneable by size as a result of the quantum confinement effect and are particularly interesting for applications in biology as luminescent labels. Control over a... |
 |
Quantum Dots: A Survey of the Properties of Artificial Atoms by T. Chakraborty (Author) This book deals with the electronic and optical properties of two low-dimensional systems: quantum dots and quantum antidots and is divided into two parts. Part one is a self-contained monograph which describes in detail the theoretical and experimental background for exploration of electronic states of the quantum-confined systems. Starting from the single-electron picture of the system, the book describes various experimental methods that provide important information on these systems. Concentrating on many-electron systems, theoretical developments are described in detail and their experimental consequences are also discussed. The field has witnessed an almost explosive growth and some of the future directions of explorations are highlighted towards the end of the monograph. The... |
 |
Quantum Wells, Wires and Dots: Theoretical and Computational Physics of Semiconductor Nanostructures by Paul Harrison (Author) Quantum Wells, Wires and Dots Second Edition: Theoretical and Computational Physics of Semiconductor Nanostructures provides all the essential information, both theoretical and computational, for complete beginners to develop an understanding of how the electronic, optical and transport properties of quantum wells, wires and dots are calculated. Readers are lead through a series of simple theoretical and computational examples giving solid foundations from which they will gain the confidence to initiate theoretical investigations or explanations of their own. Emphasis on combining the analysis and interpretation of experimental data with the development of theoretical ideas Complementary to the more standard texts Aimed at the physics community at large, rather than... |
 |
Quantum Dots: Fundamentals, Applications, and Frontiers: Proceedings of the NATO ARW on Quantum Dots: Fundamentals, Applications and Frontiers, Crete, ... II: Mathematics, Physics and Chemistry) by Bruce A. Joyce (Editor), Pantelis C. Kelires (Editor), Anton G. Naumovets (Editor), Dimitri D. Vvedensky (Editor) This volume contains papers delivered at a NATO Advanced Research Workshop and provides a broad introduction to all major aspects of quantum dot structures. Such structures have been produced for studies of basic physical phenomena, for device fabrication and, on a more speculative level, have been suggested as components of a solid-state realization of a quantum computer. The book is structured so that the reader is introduced to the methods used to produce and control quantum dots, followed by discussions of their structural, electronic, and optical properties. It concludes with examples of how their optical properties can be used in practical devices, including lasers and light-emitting diodes operating at the commercially important wavelengths of 1.3 µm and 1.55 µm. |
 |
Optics of Quantum Dots and Wires (Artech House Solid-State Technology Library) by Garnett W. Bryant (Editor), Glenn S. Solomon (Editor) Quantum technology is the key to next-generation optoelectronics and laser semiconductors, and this new cutting-edge book is an in-depth examination of how quantum dots and wires are fabricated and applied to optics. You find a solid tutorial on the optical properties of nanoscale dots and wires that explains the current state of this technology and why it is so promising. The book presents a detailed survey of techniques based on molecular beam epitaxial growth for fabricating semiconductor quantum dots and wires. You learn how to assess these growth strategies for insertion of dots and wires into devices. Special focus is given to bottom-up growth methods that have the most potential for fabricating atomically precise structures. Each type of these structures is characterized... |
 |
Inventing Reality The Quantum Dots (Performer) The Quantum Dots' impressive new release, "Inventing Reality," is definitely not your average fledgling debut. Having already been compared to everything from Depeche Mode to Tool, the Quantum Dots expertly showcase their diverse talents and defy classification by delving into everything from ambient electronica, to powernoise, to thrash-metal on this CD. Sure to appeal to a broad range of listeners, from metalheads to club kids, "Inventing Reality" also features the guest-talents of a number of respected Pacific Northwest artists, including violinist Jyri Glynn of The Sins and Ned Wahl of Chemlab and Halo-Black. |
 |
Quantum Dots (Selected Topics in Electronics and Systems, Vol. 25) by E. Borovitskaya (Editor), Michael Shur (Editor) Provides comprehensive reviews of all aspects of quantum dot systems. For scientists, engineers and graduate students working in the area of semiconductor materials and devices. |
 |
Inventing Reality The Quantum Dots (Primary Contributor) |
| © 2009 BrightSurf.com |