Fluorescence intermittency in single cadmium selenide nanocrystals

Nirmal, M.; Dabbousi, B. O.; Bawendi, Moungi G.; Macklin, John J.; Trautman, J. K.; Harris, Timothy D; Brus, L. E.

doi:10.1038/383802a0

Cited by 1,898 publications

(1,873 citation statements)

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“…170 The observed fluorescence line shape was Lorentzian. Interestingly, the full width at half maximum was ~23 meV, nearly equivalent to k B T at room temperature.…”

Section: Fluorescence Spectra For Individual Swntsmentioning

confidence: 89%

“…169 It is also possible to observe additional unique behavior such as fluorescence intermittency (i.e., blinking) that cannot be observed for bulk samples. 170 Ensemble studies benefit significantly from the clarification of fundamental photophysical behavior that is exposed on the single particle level, which has catalyzed single molecule studies for many fluorescent systems including dyes, 171-174 polymer chains, 175,176 proteins, [177][178][179] semiconductor quantum dots, 170,180,181 and single-walled carbon nanotubes. 72,77,182 The observation of fluorescence from individual SWNTs was first reported in 2003 and, importantly, confirmed spectral assignments of (n,m) made on the ensemble level.…”

Section: Principles Of Single Molecule Spectroscopymentioning

confidence: 99%

“…Blinking is considered to be a definitive hallmark of fluorescence from a single QD, 170 and time traces were collected for each nanoparticle to confirm that individual QDs were being studied.…”

Section: Fluorescence Intensities Of Single Moleculesmentioning

confidence: 99%

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Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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Single-walled carbon nanotubes (SWNTs) are cylindrical graphitic molecules that have remained at the forefront of nanomaterials research since 1991, largely due to their exceptional and unusual mechanical, electrical, and optical properties. The motivation for understanding how nanotubes interact with light (i.e., SWNT photophysics) is both fundamental and applied. Individual nanotubes may someday be used as superior near-infrared fluorophores, biological tags and sensors, and components for ultrahigh-speed optical communications systems. Establishing an understanding of basic nanotube photophysics is intrinsically significant and should enable the rapid development of such innovations. Unlike conventional molecules, carbon nanotubes are synthesized as heterogeneous samples, composed of molecules with different diameters, chiralities, and lengths. Because a nanotube can be either metallic or semiconducting depending on its particular molecular structure, SWNT samples are also mixtures of conductors and semiconductors. Early progress in understanding the optical characteristics of SWNTs was limited because nanotubes aggregate when synthesized, causing a mixing of the energy states of different nanotube structures. Recently, significant improvements in sample preparation have made it possible to isolate individual nanotubes, enabling many advances in characterizing their optical properties. In this Account, single-molecule confocal microscopy and spectroscopy were implemented to study the fluorescence from individual nanotubes. Single-molecule measurements naturally circumvent the difficulties associated with SWNT sample inhomogeneities. Intrinsic SWNT photoluminescence has a simple narrow Lorentzian line shape and a polarization dependence, as expected for a one-dimensional system. Although the local environment heavily influences the optical transition wavelength and intensity, single nanotubes are exceptionally photostable. In fact, they have the unique characteristic that their single molecule fluorescence intensity remains constant over time; SWNTs do not “blink” or photobleach under ambient conditions. In addition, transient absorption spectroscopy was used to examine the relaxation dynamics of photoexcited nanotubes and to elucidate the nature of the SWNT excited state. For metallic SWNTs, very fast initial recovery times (300–500 fs) corresponded to excited-state relaxation. For semiconducting SWNTs, an additional slower decay component was observed (50–100 ps) that corresponded to electron–hole recombination. As the excitation intensity was increased, multiple electron–hole pairs were generated in the SWNT; however, these e−h pairs annihilated each other completely in under 3 ps. Studying the dynamics of this annihilation process revealed the lifetimes for one, two, and three e−h pairs, which further confirmed that the photoexcitation of SWNTs produces not free electrons but rather one-dimensional bound electron–hole pairs (i.e., excitons). In summary, nanotube photophysics is a rapidly developing area o...

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“…170 The observed fluorescence line shape was Lorentzian. Interestingly, the full width at half maximum was ~23 meV, nearly equivalent to k B T at room temperature.…”

Section: Fluorescence Spectra For Individual Swntsmentioning

confidence: 89%

Section: Principles Of Single Molecule Spectroscopymentioning

confidence: 99%

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Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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“…The fluorescence intensity stochastically changes between bright and dark regimes, commonly referred to as onand off-states. Furthermore, this blinking does not follow a simple two-level quantum jump model, but instead displays approximately power-law (Lévy) statistics over many decades in time [3][4][5][6][7][8] . Similar non-Poissonian statistics have been observed in electron transport through colloidal nanocrystal (NC) arrays 9 .…”

mentioning

confidence: 94%

“…The origin of the observed Lévy statistics has been investigated extensively, with several models proposed in the 15 years since the first observation of power-law blinking [3][4][5] . Although the details of the mechanism are still poorly understood, it is thought that NCs become 'dark' , cease emitting light, when one of the charge carriers in a photoexcited exciton becomes trapped at the surface of the NC or tunnels off the NC into the environment, leaving a net charge delocalized in the NC core.…”

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confidence: 99%

Collective fluorescence enhancement in nanoparticle clusters

et al. 2011

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many nanoscale systems are known to emit light intermittently under continuous illumination. In the fluorescence of single semiconductor nanoparticles, the distributions of bright and dark periods ('on' and 'off' times) follow Lévy statistics. Although fluorescence from single-quantum dots and from macroscopic quantum dot ensembles has been studied, there has been little study of fluorescence from small ensembles. Here we show that blinking nanorods (nRs) interact with each other in a cluster, and the interactions affect the blinking statistics. The ontimes in the fluorescence of a nR cluster increase dramatically; in a cluster with N nRs, the maximum on-time increases by a factor of N or more compared with the combined signal from N well-separated nRs. our study emphasizes the use of statistical properties in identifying the collective dynamics. The scaling of this interaction-induced increase of on-times with number of nRs reveals a novel collective effect at the nanoscale.

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Fluorescence imaging of single molecules in polymer microspheres

Barnes

McNamara

et al. 1999

Cytometry

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We report on far‐field fluorescence imaging of single molecules in spherical polymer microparticles produced from solution by using microdroplet techniques. The fluorescence photobleaching quantum yields of rhodamine 6G in a common water‐soluble polymer (polyvinyl alcohol) are at least five times smaller, corresponding to proportionally larger average fluorescence signals, than those in ethanolic solvents. This allows for acquisition of multiple images from a single molecule on a time scale of several minutes. We also show that fluorescent images of single molecules in microspheres can be calculated from semiclassic electrodynamics, which may ultimately be useful in retrieving dynamical information from experimental images. Cytometry 36:169–175, 1999. © 1999 Wiley‐Liss, Inc.

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Fluorescence intermittency in single cadmium selenide nanocrystals

Cited by 1,898 publications

References 19 publications

Photophysics of Individual Single-Walled Carbon Nanotubes

Photophysics of Individual Single-Walled Carbon Nanotubes

Collective fluorescence enhancement in nanoparticle clusters

Fluorescence imaging of single molecules in polymer microspheres

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