Enhanced laser cooling of rare-earth-ion-doped nanocrystalline powders

Ruan, Xiulin; Kaviany, Massoud

doi:10.1103/physrevb.73.155422

Cited by 66 publications

(43 citation statements)

References 48 publications

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“…Note that the thin film h-BN shows low and high-energy enhancement and scatter in D p due to the substrate phonon. 15,16 Xenon and Fluorine have eight and seven valence electrons, respectively, so XeF 6 consists of six Xe-F bonds and one lone electron pair as shown in Fig. 2(a).…”

Section: Introductionmentioning

confidence: 99%

Phonocatalysis. An ab initio simulation experiment

Kim

Kaviany

2016

AIP Advances

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Using simulations, we postulate and show that heterocatalysis on large-bandgap semiconductors can be controlled by substrate phonons, i.e., phonocatalysis. With ab initio calculations, including molecular dynamic simulations, the chemisorbed dissociation of XeF6 on h-BN surface leads to formation of XeF4 and two surface F/h-BN bonds. The reaction pathway and energies are evaluated, and the sorption and reaction emitted/absorbed phonons are identified through spectral analysis of the surface atomic motion. Due to large bandgap, the atomic vibration (phonon) energy transfer channels dominate and among them is the match between the F/h-BN covalent bond stretching and the optical phonons. We show that the chemisorbed dissociation (the pathway activation ascent) requires absorption of large-energy optical phonons. Then using progressively heavier isotopes of B and N atoms, we show that limiting these high-energy optical phonons inhibits the chemisorbed dissociation, i.e., controllable phonocatalysis.

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Section: Introductionmentioning

confidence: 99%

Phonocatalysis. An ab initio simulation experiment

Kim

Kaviany

2016

AIP Advances

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“…Other nonequilibrium phonon harvesting schemes have received attention for their ability to surpass the TE limits in scale and efficiency. These include the laser cooling of ion-doped materials through antiStokes florescence 11,12 , and the use of in-situ electron barriers to recycle phonons emitted during the Joule heating 13,14 . Conversely, the pV cell focuses on power generation.…”

Section: Introductionmentioning

confidence: 99%

Phonovoltaic. I. Harvesting hot optical phonons in a nanoscalep−njunction

Melnick

Kaviany

2016

Phys. Rev. B

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The phonovoltaic (pV) cell is similar to the photovoltaic. It harvests nonequilibrium (hot) optical phonons (E p,O ) more energetic than the bandgap (∆E e,g ) to generate power in a p-n junction.We examine the theoretical electron-phonon and phonon-phonon scattering rates, the Boltzmann transport of electrons, and the diode equation and hydrodynamic simulations to describe the operation of a pV cell and develop an analytic model predicting its efficiency. Our findings indicate that a pV material with E p,O ≃ ∆E e,g ≫ k B T , where k B T is the thermal energy, and a strong interband electron-phonon coupling surpasses the thermoelectric limit, provided the optical phonon population is excited in a nanoscale cell -enabling the ensuing local nonequilibrium. Finding and tuning a material with these properties is challenging. In Part II (this issue), we tune the bandgap of graphite within density functional theory through hydrogenation and the application of uniaxial strains. The bandgap is tuned to resonate with its energetic optical phonon modes and calculate the ab initio electron-phonon and phonon-phonon scattering rates. While hydrogenation degrades the strong electron-phonon coupling in graphene such that the figure of merit vanishes, we outline the methodology for a continued material search.

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“…Ruan and Kaviany have theoretically demonstrated that the cooling efficiency can be dramatically enhanced then host material containes rare-ion-doped nanocrystalline powder (Ruan & Kaviany, 2006). Light localization effects increase the photon density, leading to an enhanced absorptivity and the phonon spectrum is modified due to finite size of the nanopowder.…”

Section: Laser Cooling Of Rare-earth Doped Solidsmentioning

confidence: 99%

Laser cooling of solids

2010

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Laser cooling of solids, sometimes also known as optical refrigeration, is a fast developing area of optical science, investigating the interaction of light with condensed matter. Apart from being of fundamental scientific interest, this topic addresses a very important practical issue: design and construction of laser pumped solid-state cryocoolers, which are compact, free from mechanical vibrations, moving parts, fluids and can cause only low electromagnetic interference in the cooled area. The optical cryocooler has a broad area of applications such as in the development of magnetometers for geophysical sensors, in biomedical sensing and can be beneficial for satellite instrumentations and small sensors, where compactness and the lack of vibrations are very important. Simply, a laser cooler works on the conversion of low energy pump photons into high-energy anti-Stokes fluorescence photons by extracting some of the phonons (heat energy) in a material. That is, the process of laser cooling of solids is based on anti-Stokes fluorescence also known as luminescence upconversion, when light quanta in the red tail of the absorption spectrum are absorbed from a pump laser, and blue-shifted photons are spontaneously emitted. The extra energy extracted from the solid-state lattice in the form of the phonons is the quanta of vibrational energy which generates heat. The idea to cool solids with anti-Stokes fluorescence was proposed in 1929 by Peter Pringsheim and first demonstrated experimentally by Epstein's research team in 1995. In 1999, Steven Bowman proposed to use the optical refrigeration by anti-Stokes fluorescence within the laser medium to balance the heat generated by the Stokes shifted stimulated emission in a high-power solid-state bulk laser. Such a laser without internal heating named radiation-balanced or athermal laser was experimentally demonstrated for the first time in 2002. At the present time laser cooling of solids can be largely divided into three main areas: laser cooling of rare-earth doped solids, laser cooling in semiconductors and radiation-balanced lasers. All three areas are very interesting and important and will be considered in this paper.

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Enhanced laser cooling of rare-earth-ion-doped nanocrystalline powders

Cited by 66 publications

References 48 publications

Phonocatalysis. An ab initio simulation experiment

Phonocatalysis. An ab initio simulation experiment

Phonovoltaic. I. Harvesting hot optical phonons in a nanoscalep−njunction

Laser cooling of solids

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