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Subwavelength imaging through ion-beam-induced upconversion.

Mi Z, Zhang Y, Vanga SK, Chen CB, Tan HQ, Watt F, Liu X, Bettiol AA - Nat Commun (2015)

Bottom Line: Here we present a new method for subwavelength imaging by combining lanthanide-doped upconversion nanocrystals with the ionoluminescence imaging technique.We experimentally observed that the ion beam can be used as a new form of excitation source to induce photon upconversion in lanthanide-doped nanocrystals.This approach enables luminescence imaging and simultaneous mapping of cellular structures with a spatial resolution of sub-30 nm.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Centre for Ion Beam Applications, National University of Singapore, Singapore 117542, Singapore.

ABSTRACT
The combination of an optical microscope and a luminescent probe plays a pivotal role in biological imaging because it allows for probing subcellular structures. However, the optical resolutions are largely constrained by Abbe's diffraction limit, and the common dye probes often suffer from photobleaching. Here we present a new method for subwavelength imaging by combining lanthanide-doped upconversion nanocrystals with the ionoluminescence imaging technique. We experimentally observed that the ion beam can be used as a new form of excitation source to induce photon upconversion in lanthanide-doped nanocrystals. This approach enables luminescence imaging and simultaneous mapping of cellular structures with a spatial resolution of sub-30 nm.

No MeSH data available.


Related in: MedlinePlus

Experimental setup and proposed ionoluminescence mechanism.(a) Artist's view of the basic experimental setup. The focused beam with a spot size of sub-30 nm features can be achieved using a spaced triplet of compact magnetic quadrupole lenses. A Si surface barrier detector is equipped for measuring the energy loss distribution of the ions. (b) Calculated energy distribution of the ionized electrons by bombarding the MeV α-particles on the lanthanide-doped nanocrystals, showing different cross-sections of the resulting electrons at specific energies. Note that most of the ionized electrons have energies mainly located in the visible and infrared spectral region. (c) Proposed upconversion mechanism under α-beam irradiation. The incident helium ions with energy of E0 deposit a certain amount of energy (ΔE) onto the crystal to cause the atomic ionization inside the crystal. Subsequently, the ionized secondary electrons can release their energy, most likely during the electron-hole recombination process and successively transfer the energy to Yb3+ and Tm3+. An energy transfer from the excited Yb3+ to its neighbouring Tm3+ ions then populates the excited states (for example, 3H4, 1G4 and 1D2) of Tm3+.
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f1: Experimental setup and proposed ionoluminescence mechanism.(a) Artist's view of the basic experimental setup. The focused beam with a spot size of sub-30 nm features can be achieved using a spaced triplet of compact magnetic quadrupole lenses. A Si surface barrier detector is equipped for measuring the energy loss distribution of the ions. (b) Calculated energy distribution of the ionized electrons by bombarding the MeV α-particles on the lanthanide-doped nanocrystals, showing different cross-sections of the resulting electrons at specific energies. Note that most of the ionized electrons have energies mainly located in the visible and infrared spectral region. (c) Proposed upconversion mechanism under α-beam irradiation. The incident helium ions with energy of E0 deposit a certain amount of energy (ΔE) onto the crystal to cause the atomic ionization inside the crystal. Subsequently, the ionized secondary electrons can release their energy, most likely during the electron-hole recombination process and successively transfer the energy to Yb3+ and Tm3+. An energy transfer from the excited Yb3+ to its neighbouring Tm3+ ions then populates the excited states (for example, 3H4, 1G4 and 1D2) of Tm3+.

Mentions: The basic experimental setup is shown in Fig. 1a. A beam of 1.6 MeV helium ions (α-particles) is produced by a Singletron ion accelerator. A sample comprising NaYF4:Yb/Tm nanorods is placed in a vacuum chamber (10−6 mbar) at a position situated exactly along the beam path. A customized double-piece parabolic mirror with front and rear openings is used to collect emission photons induced by the ion beam and, concurrently, allow the ion beam to pass through the mirror (Supplementary Fig. 1). The convergent lens-coupled parabolic mirror allows the emitted light to be focused into a fibre, which guides the light out of the vacuum chamber. The emitted photons are then captured either by a photomultiplier tube for luminescence imaging or by a spectrometer for spectroscopic characterization. A Si surface barrier detector is used to perform scanning transmission ion microscopy imaging by measuring the energy loss during the penetration of the ions into a given sample2829.


Subwavelength imaging through ion-beam-induced upconversion.

Mi Z, Zhang Y, Vanga SK, Chen CB, Tan HQ, Watt F, Liu X, Bettiol AA - Nat Commun (2015)

Experimental setup and proposed ionoluminescence mechanism.(a) Artist's view of the basic experimental setup. The focused beam with a spot size of sub-30 nm features can be achieved using a spaced triplet of compact magnetic quadrupole lenses. A Si surface barrier detector is equipped for measuring the energy loss distribution of the ions. (b) Calculated energy distribution of the ionized electrons by bombarding the MeV α-particles on the lanthanide-doped nanocrystals, showing different cross-sections of the resulting electrons at specific energies. Note that most of the ionized electrons have energies mainly located in the visible and infrared spectral region. (c) Proposed upconversion mechanism under α-beam irradiation. The incident helium ions with energy of E0 deposit a certain amount of energy (ΔE) onto the crystal to cause the atomic ionization inside the crystal. Subsequently, the ionized secondary electrons can release their energy, most likely during the electron-hole recombination process and successively transfer the energy to Yb3+ and Tm3+. An energy transfer from the excited Yb3+ to its neighbouring Tm3+ ions then populates the excited states (for example, 3H4, 1G4 and 1D2) of Tm3+.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660043&req=5

f1: Experimental setup and proposed ionoluminescence mechanism.(a) Artist's view of the basic experimental setup. The focused beam with a spot size of sub-30 nm features can be achieved using a spaced triplet of compact magnetic quadrupole lenses. A Si surface barrier detector is equipped for measuring the energy loss distribution of the ions. (b) Calculated energy distribution of the ionized electrons by bombarding the MeV α-particles on the lanthanide-doped nanocrystals, showing different cross-sections of the resulting electrons at specific energies. Note that most of the ionized electrons have energies mainly located in the visible and infrared spectral region. (c) Proposed upconversion mechanism under α-beam irradiation. The incident helium ions with energy of E0 deposit a certain amount of energy (ΔE) onto the crystal to cause the atomic ionization inside the crystal. Subsequently, the ionized secondary electrons can release their energy, most likely during the electron-hole recombination process and successively transfer the energy to Yb3+ and Tm3+. An energy transfer from the excited Yb3+ to its neighbouring Tm3+ ions then populates the excited states (for example, 3H4, 1G4 and 1D2) of Tm3+.
Mentions: The basic experimental setup is shown in Fig. 1a. A beam of 1.6 MeV helium ions (α-particles) is produced by a Singletron ion accelerator. A sample comprising NaYF4:Yb/Tm nanorods is placed in a vacuum chamber (10−6 mbar) at a position situated exactly along the beam path. A customized double-piece parabolic mirror with front and rear openings is used to collect emission photons induced by the ion beam and, concurrently, allow the ion beam to pass through the mirror (Supplementary Fig. 1). The convergent lens-coupled parabolic mirror allows the emitted light to be focused into a fibre, which guides the light out of the vacuum chamber. The emitted photons are then captured either by a photomultiplier tube for luminescence imaging or by a spectrometer for spectroscopic characterization. A Si surface barrier detector is used to perform scanning transmission ion microscopy imaging by measuring the energy loss during the penetration of the ions into a given sample2829.

Bottom Line: Here we present a new method for subwavelength imaging by combining lanthanide-doped upconversion nanocrystals with the ionoluminescence imaging technique.We experimentally observed that the ion beam can be used as a new form of excitation source to induce photon upconversion in lanthanide-doped nanocrystals.This approach enables luminescence imaging and simultaneous mapping of cellular structures with a spatial resolution of sub-30 nm.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Centre for Ion Beam Applications, National University of Singapore, Singapore 117542, Singapore.

ABSTRACT
The combination of an optical microscope and a luminescent probe plays a pivotal role in biological imaging because it allows for probing subcellular structures. However, the optical resolutions are largely constrained by Abbe's diffraction limit, and the common dye probes often suffer from photobleaching. Here we present a new method for subwavelength imaging by combining lanthanide-doped upconversion nanocrystals with the ionoluminescence imaging technique. We experimentally observed that the ion beam can be used as a new form of excitation source to induce photon upconversion in lanthanide-doped nanocrystals. This approach enables luminescence imaging and simultaneous mapping of cellular structures with a spatial resolution of sub-30 nm.

No MeSH data available.


Related in: MedlinePlus