ChemInform Abstract: On—Off Blinking and Multiple Bright States of Single Europium Ions in Eu³⁺: Y₂O₃ Nanocrystals.

Abstract

2000 luminescence, fluorescence luminescence, fluorescence (solids and liquids) D 6540 -009On-Off Blinking and Multiple Bright States of Single Europium Ions in Eu 3+ : Y 2 O 3 Nanocrystals.-Eu 3+ :Y 2 O 3 nanocrystals are prepared by an inverse micelle technique using 1:10 Eu 3+ :Y 2 O 3 stoichiometry. The nanoparticles ranging in size from 2 to 15 nm are characterized by AFM. It is expected that a significant fraction of the nanoparticles contain only a single Eu 3+ ion. The prepared nanoparticles are continuously illuminated with the 514.5 nm line from an argon ion laser. The illuminated single Eu 3+ ions undergo on-off blinking on a variable time scale. Switching between different bright levels is also observed with a modulation rate that is dependent on pump-laser intensity. These features of single ion luminescence are not observed for larger particles with multiple chromophores.-(BARNES, M. D.; MEHTA, A.; THUNDAT, T.; BHARGAVA, R. N.; CHHABRA, V.; KULKARNI, B.; J.

Non-blinking and photostable upconverted luminescence from single lanthanide-doped nanocrystals

“…3C) follows a Poisson distribution, suggesting that the upconverted luminescence is shot noise limited and no other photon noise sources, such as blinking, are observed down to 1 ms (31). This observation differs from luminescence in a single nanocrystal doped with a single lanthanide ion, where blinking was observed and associated with the inherently long excited-state lifetime (up to several milliseconds) of lanthanide ions (32). In our experiment, each UCNP contains approximately 700 Er 3ϩ ions and 7,000 Yb 3ϩ ions based on the EDS analysis and average particle size, so that this non-blinking is due to the steady-state emissions from multiple ions in a single UCNP (32,33).…”

“…This observation differs from luminescence in a single nanocrystal doped with a single lanthanide ion, where blinking was observed and associated with the inherently long excited-state lifetime (up to several milliseconds) of lanthanide ions (32). In our experiment, each UCNP contains approximately 700 Er 3ϩ ions and 7,000 Yb 3ϩ ions based on the EDS analysis and average particle size, so that this non-blinking is due to the steady-state emissions from multiple ions in a single UCNP (32,33). The absence of photobleaching and blinking significantly improves signal-to-noise and signal-to-background statistics, allowing one, for example, to precisely and quickly determine the center position of individual UCNPs with nanometer-scale accuracy (34), or to track cellular proteins for extended periods without uncertainties arising from intermittent loss of emission (35).…”

Basic Research Needs for Countering Terrorism

“…They have advantages over conventional fluorescent molecular probes, including ease of synthesis, broadband absorption, narrowband emission, and wavelength selection by quantum size effects. 45, 46 An array of such nanoparticles tailored to emit at selected discrete wavelengths can be used to identify pathogens, for example, in microfluidic systems in real time in a field setting for evaluating residual agent levels and hence risk.…”

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“…In contrast to traditional organic-dyebased detection systems, this unique UCL sensing mechanism has several innate advantages including no autofluorescence from biosamples, higher light penetration depth, less damage to biosamples, and no photobleaching [23,24]. Herein, we present the design and biological evaluation of an organic fluorophoreattached UCNP probe for selective UCL detection of H 2 O 2 .…”