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Title: Efficient photoluminescence of Mn2+-doped ZnS quantum dots excited by two-photon absorption in near-infrared window II
Authors: Subha, Radhu
Nalla, Venkatram
Yu, Jung Ho
Jun, Samuel Woojoo
Shin, Kwangsoo
Hyeon, Taeghwan
Ji, Wei
Vijayan, C.
Keywords: DRNTU::Science::Physics::Atomic physics::Quantum theory
Issue Date: 2013
Source: Subha, R., Nalla, V., Yu, J. H., Jun, S. W., Shin, K., Hyeon, T., Vijayan, C., & Ji, W. (2013). Efficient Photoluminescence of Mn2+-Doped ZnS Quantum Dots Excited by Two-Photon Absorption in Near-Infrared Window II. The Journal of Physical Chemistry C, 117(40), 20905-20911.
Series/Report no.: The journal of physical chemistry C
Abstract: Highly fluorescing biological labels with excitation in near-infrared window II have attracted the interest of scientific community as they are capable of increasing both penetration depth and imaging quality. However, studies on the utilization of quantum dots (QDs) in biological imaging appear to be rather limited to the near-infrared window I (NIR-I: 650–950 nm). We herein report on the observation of efficient photoluminescence (PL) in Mn2+-doped ZnS QDs excited by two-photon absorption (2PA) in near-infrared window II (NIR-II: 1000–1350 nm). Multiphoton-absorption-induced PL measurements indicate that these biocompatible QDs exhibit a two-photon action cross-section of 265 GM at 1180 nm, the highest value reported to date among conventional fluorescent probes on excitation in NIR-II. This value is 1–2 orders of magnitude higher than that for organic dye molecules excited by NIR-I photons and 3–4 times greater than that of fluorescent proteins excited in the NIR-II. The underlying NIR-II excitation mechanism for the Mn2+ emission at 586 nm on account of the 4T1–6A1 transition is attributed to the transitions from the valence subband of ZnS QDs (or ground states of Mn2+ ions) to the excited states of Mn2+ ions by direct two-photon absorption. Transient PL measurements reveal single exponential decay with a PL lifetime of 0.35 ± 0.03 ms irrespective of excitation wavelength, which are 4–5 orders longer than that of conventional fluorescent probes. With the excitation in NIR-II window and the unique combination of photophysical properties such as a greater two-photon action cross-section, a longer PL lifetime, and larger anti-Stokes shift (450 nm or more), Mn2+-doped ZnS QDs appear to be a promising candidate for deep tissue imaging applications.
ISSN: 1932-7455
DOI: 10.1021/jp404124c
Schools: School of Physical and Mathematical Sciences 
Rights: © 2013 American Chemical Society. This is the author created version of a work that has been peer reviewed and accepted for publication by The journal of physical chemistry C, American Chemical Society. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [DOI:].
Fulltext Permission: open
Fulltext Availability: With Fulltext
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