Laser refrigeration of optically levitated sodium yttrium fluoride nanocrystals

Luntz-Martin, Danika R.; Felsted, R. Greg; Dadras, Siamak; Pauzauskie, Peter J.; Vamivakas, A. Nick

doi:10.1364/ol.426334

Cited by 14 publications

(15 citation statements)

References 46 publications

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“…26,46 In preliminary experiments we observe optical refrigeration of the NaYF gel when doped with 10% ytterbium. Our measurements of this gel indicate that it can be laser cooled by approximately 0.55°C and it does not heat under laser irradiation (Figure S7), indicating that it may be a good candidate for actively-cooled anti-reflective coatings, especially due to its lack of organic ligands on the surface, as the effective cooling efficiency of a nanocrystal is reduced by the heating of organic species on the surface 47,48 .…”

Section: Resultsmentioning

confidence: 95%

Multi-Step Crystallization and Chemical Evolution of Sodium Yttrium Fluoride

Pauzauskie

Bard

Felsted

et al. 2021

Preprint

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Two-step crystallization mechanisms based on spinodal decomposition followed by nucleation are commonly observed both in the laboratory and in nature. While this pathway may require chemical reactions, subsequent nucleation and growth are often considered as separate, discrete events from the reaction itself. Recent work has also shown a distinct intermediate step involving the formation of an amorphous aggregate. Here we report a novel four-step mechanism in the aqueous synthesis of sodium yttrium fluoride involving 1) the segregation of aqueous ions into a dense liquid phase, 2) the formation of an amorphous aggregate, 3) nucleation of a cubic YF3 phase, and 4) subsequent solid-state diffusion of sodium and fluoride ions to form a final NaYF4 phase. The final step involves a continuous, gradual change of the solid phase’s chemical stoichiometry from YF3 toward NaYF4. Unlike previously studied nucleation and growth mechanisms, the stoichiometry of the final solid phase evolves throughout the crystallization process rather than being determined at nucleation. This novel four-step mechanism provides a new perspective into the nucleation and growth of many other crystalline materials given the ubiquity of nonstoichiometric compounds in nature.

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Section: Resultsmentioning

confidence: 95%

Multi-Step Crystallization and Chemical Evolution of Sodium Yttrium Fluoride

Pauzauskie

Bard

Felsted

et al. 2021

Preprint

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“…On the basis of their PLQY values, some of the samples reported here should show optical refrigeration (as a NC ensemble); however, this is within the uncertainty of the PLQY measurements. We have tried to measure optical refrigeration in solutions and on films by analyzing the change of emission peak ratios as mentioned by Luntz-Martin et al 63 (influenced by the number of phonons present, Supporting Information SI-18 and SI-19), but the results do not yet convincingly show evidence of cooling, possibly as a result of too efficient heat transfer from the surroundings to the NCs. Efforts to measure optical refrigeration on single NCs using optical levitation, as reported before, 15,64−66 are currently under way.…”

Section: ■ Discussionmentioning

confidence: 99%

“…On the basis of their PLQY values, some of the samples reported here should show optical refrigeration (as a NC ensemble); however, this is within the uncertainty of the PLQY measurements. We have tried to measure optical refrigeration in solutions and on films by analyzing the change of emission peak ratios as mentioned by Luntz-Martin et al . (influenced by the number of phonons present, Supporting Information SI-18 and SI-19), but the results do not yet convincingly show evidence of cooling, possibly as a result of too efficient heat transfer from the surroundings to the NCs.…”

Section: Discussionmentioning

confidence: 99%

Understanding and Preventing Photoluminescence Quenching to Achieve Unity Photoluminescence Quantum Yield in Yb:YLF Nanocrystals

Mulder

Meijer

Blaaderen

et al. 2023

ACS Appl. Mater. Interfaces

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Ytterbium-doped LiYF4 (Yb:YLF) is a commonly used material for laser applications, as a photon upconversion medium, and for optical refrigeration. As nanocrystals (NCs), the material is also of interest for biological and physical applications. Unfortunately, as with most phosphors, with the reduction in size comes a large reduction of the photoluminescence quantum yield (PLQY), which is typically associated with an increase in surface-related PL quenching. Here, we report the synthesis of bipyramidal Yb:YLF NCs with a short axis of ∼60 nm. We systematically study and remove all sources of PL quenching in these NCs. By chemically removing all traces of water from the reaction mixture, we obtain NCs that exhibit a near-unity PLQY for an Yb3+ concentration below 20%. At higher Yb3+ concentrations, efficient concentration quenching occurs. The surface PL quenching is mitigated by growing an undoped YLF shell around the NC core, resulting in near-unity PLQY values even for fully Yb3+-based LiYbF4 cores. This unambiguously shows that the only remaining quenching sites in core-only Yb:YLF NCs reside on the surface and that concentration quenching is due to energy transfer to the surface. Monte Carlo simulations can reproduce the concentration dependence of the PLQY. Surprisingly, Förster resonance energy transfer does not give satisfactory agreement with the experimental data, whereas nearest-neighbor energy transfer does. This work demonstrates that Yb3+-based nanophosphors can be synthesized with a quality close to that of bulk single crystals. The high Yb3+ concentration in the LiYbF4/LiYF4 core/shell nanocrystals increases the weak Yb3+ absorption, making these materials highly promising for fundamental studies and increasing their effectiveness in bioapplications and optical refrigeration.

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“…Recently, it has been shown that by exploiting the inelastic scattering of light by rare earth nanocrystals, it is also possible to extract heat from the system, that is, optical cooling in liquid environments. This has been first demonstrated with the study of so‐called “Cold Brownian motion” [ 132,133 ] as opposed to “Hot Brownian motion”. [ 134 ] Meanwhile, there are first attempts to integrate these materials and techniques into fluidic systems.…”

Section: Perspectivesmentioning

confidence: 99%

Thermoplasmonic Manipulation for the Study of Single Polymers and Protein Aggregates

Simon

Thalheim

Cichos

et al. 2023

Macro Chemistry & Physics

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Heat generation by means of plasmonic structures, which is at the heart of thermoplasmonics, has stimulated intense research on the manipulation of matter in liquid environments. Tiny noble metal structures with dimensions of a few tens of nanometers thereby serve as heat sources generating large temperature gradients. As a result, thermophoretic drifts occur, concentration fields form, or charge separation takes place. But also hydrodynamic boundary flows, which play an important role in microfluidic environments, can be induced. These processes remotely triggered by optically generated local dynamic temperature fields offer novel possibilities for manipulating and studying not only colloids but in particular also single molecules and their aggregates in solution.

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Laser refrigeration of optically levitated sodium yttrium fluoride nanocrystals

Cited by 14 publications

References 46 publications

Multi-Step Crystallization and Chemical Evolution of Sodium Yttrium Fluoride

Multi-Step Crystallization and Chemical Evolution of Sodium Yttrium Fluoride

Understanding and Preventing Photoluminescence Quenching to Achieve Unity Photoluminescence Quantum Yield in Yb:YLF Nanocrystals

Thermoplasmonic Manipulation for the Study of Single Polymers and Protein Aggregates

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