A fluorescence light source device includes a wavelength conversion member that emits fluorescence by excitation laser light. The wavelength conversion member has an excitation laser light receiving surface including a periodic structure having a periodic array of conical or truncated projections with an aspect ratio, which is a ratio of the height of the projection to the pitch in the periodic structure, of not lower than 0.2. The wavelength conversion member is formed from a phosphor composed of a polycrystal and contains a micro-scatterer with a refractive index of not lower than 1.0 for scattering the excitation laser light and fluorescence emitted from the phosphor. A ratio (T/R) between a light transmission percentage T [%] in the wavelength conversion member and a light reflection percentage R [%] in the wavelength conversion member is 1 to 20.

A fluorescence light source device includes a wavelength conversion member that emits fluorescence by excitation laser light. The wavelength conversion member has an excitation laser light receiving surface including a periodic structure having a periodic array of conical or truncated projections with an aspect ratio, which is a ratio of the height of the projection to the pitch in the periodic structure, of not lower than 0.2. The wavelength conversion member is formed from a phosphor composed of a polycrystal and contains a micro-scatterer with a refractive index of not lower than 1.0 for scattering the excitation laser light and fluorescence emitted from the phosphor. A ratio (T/R) between a light transmission percentage T [%] in the wavelength conversion member and a light reflection percentage R [%] in the wavelength conversion member is 1 to 20.

The invention relates to a capsule comprising a shell containing a transparent and thermally conducting liquid, particles having a thermochromic coating and particles having a photochromic coating, the thermochromic particles being bulkier than photochromic particles, the liquid being such that, within a first range of temperatures, its density is greater than the density of the thermochromic particles and than the density of the photochromic particles, and such that, within a second range of temperatures greater than those of the first range, the density of the photochromic particles is less than the density of the liquid, which is itself less than the density of the thermochromic particles.

The present invention has as its object the provision of a fluorescence light source apparatus that is prevented from a drop in reflectance and can provide high emission efficiency over a long period of time without causing the problem of exfoliation of a reflection layer from a fluorescent plate. The fluorescence light source apparatus according to the present invention includes a fluorescent plate that is made of a phosphor for emitting fluorescence under excitation light and a metal oxide and has a front surface serving as an excitation light incident surface, a reflection layer disposed on a back surface side of the fluorescent layer, and a heat dissipation substrate. A sealing layer covering the back surface and a peripheral side surface of the reflection layer is provided in close contact with a peripheral area of the back surface of the fluorescent plate via an adhesion layer.

The present invention has as its object the provision of a fluorescence light source apparatus that is prevented from a drop in reflectance and can provide high emission efficiency over a long period of time without causing the problem of exfoliation of a reflection layer from a fluorescent plate. The fluorescence light source apparatus according to the present invention includes a fluorescent plate that is made of a phosphor for emitting fluorescence under excitation light and a metal oxide and has a front surface serving as an excitation light incident surface, a reflection layer disposed on a back surface side of the fluorescent layer, and a heat dissipation substrate. A sealing layer covering the back surface and a peripheral side surface of the reflection layer is provided in close contact with a peripheral area of the back surface of the fluorescent plate via an adhesion layer.

A scintillator includes a support substrate, an emission layer formed on the substrate, made of ZnO with impurities added to have an electron concentration of 2?10.sup.19 cm.sup.?3 or more and 2?10.sup.20 cm.sup.?3 or less, and for generating scintillation light in response to incidence of radiation, a protective layer formed on the emission layer and made of a material having a band gap wider than that of ZnO, and a metal layer formed on the protective layer. The support substrate is made of a material transmitting the scintillation light generated in the emission layer. Further, the metal layer functions as a reflection layer for reflecting the scintillation light from the emission layer.

A process of synthesizing GaSe nanocrystals is provided, the process including: contacting a first precursor containing gallium with a second precursor containing selenium to obtain a GaSe single precursor; and reacting the GaSe single precursor in a solvent in the presence of a ligand compound, and optionally with a third precursor including an element (A) other than gallium and selenium, to prepare a GaSe nanocrystal represented by Chemical Formula 1:

GaSe.sub.xA.sub.y[Chemical Formula 1] wherein x is about 1.1 to 3, and y is about 0.1 to 4.

A process of synthesizing GaSe nanocrystals is provided, the process including: contacting a first precursor containing gallium with a second precursor containing selenium to obtain a GaSe single precursor; and reacting the GaSe single precursor in a solvent in the presence of a ligand compound, and optionally with a third precursor including an element (A) other than gallium and selenium, to prepare a GaSe nanocrystal represented by Chemical Formula 1:

GaSe.sub.xA.sub.y[Chemical Formula 1] wherein x is about 1.1 to 3, and y is about 0.1 to 4.

An organic electroluminescent device of which emission life may be improved. The organic electroluminescent device includes an anode, an emission layer, and an anode-side hole transport layer provided between the anode and the emission layer and including an anode-side hole transport material. An electron accepting material is doped in the anode-side hole transport layer. An intermediate hole transport material layer is provided between the anode-side hole transport layer and the emission layer and includes an intermediate hole transport material, and an emission layer-side hole transport layer is provided between the intermediate hole transport material layer and the emission layer and adjacent to the emission layer. The emission layer-side hole transport layer includes an emission layer-side hole transport material represented by the following Formula 1. ##STR00001##

The invention provides novel biocompatible upconversion nanoparticle (UCNP) that comprises a core of cubic nanocrystals (e.g., comprising -Na Ln.sub.a, Ln.sub.b Ln.sub.c F.sub.4) and an epitaxial shell (e.g., formed from CaF.sub.2; wherein Ln.sub.b is Yb), and related methods of preparation and uses thereof.