This disclosure provides an optical parametric oscillator, comprising, in a light path, a first lens, a laser crystal, a second lens, a nonlinear optical crystal, and a third lens in this order, wherein an optical parametric oscillation chamber is formed between the second lens and the third lens, and the nonlinear optical crystal is a monoclinic Ga.sub.2S.sub.3 crystal, the space group of the monoclinic Ga.sub.2S.sub.3 crystal is Cc, and the unit cell parameters are a=11.1 Å, b=6.4 Å, c=7.0 Å, α=90°, β=121°, γ=90°, and Z=4.

[Objective] To provide a ceramic emitter that exhibits high radiation intensity and excellent wavelength selectivity.

[Solution] A ceramic emitter includes a polycrystalline body that has a garnet structure represented by a compositional formula R.sub.3Al.sub.5O.sub.12 (R: rare-earth element) or R.sub.3Ga.sub.5O.sub.12 (R: rare-earth element) and has pores with a porosity of 20-40%. The pores have a portion where the pores are connected to one another but not linearly continuous, inside the polycrystalline body.

[Objective] To provide a ceramic emitter that exhibits high radiation intensity and excellent wavelength selectivity.

[Solution] A ceramic emitter includes a polycrystalline body that has a garnet structure represented by a compositional formula R.sub.3Al.sub.5O.sub.12 (R: rare-earth element) or R.sub.3Ga.sub.5O.sub.12 (R: rare-earth element) and has pores with a porosity of 20-40%. The pores have a portion where the pores are connected to one another but not linearly continuous, inside the polycrystalline body.

Provided is a semiconductor nanoparticle complex in which a ligand is coordinated to a surface of a semiconductor nanoparticle. The semiconductor nanoparticle includes In and P, the ligand includes a mercapto fatty acid ester represented by the following general formula, and the mercapto fatty acid ester has an SP value of 9.30 or less.

General formula: HS—R.sub.1—COOR.sub.2 (where R.sub.1 is a C.sub.1-11 hydrocarbon group and R.sub.2 is a C.sub.1-30 hydrocarbon group). The present invention can provide a semiconductor nanoparticle complex that keeps high fluorescence quantum yield before and after purification.

Provided is a semiconductor nanoparticle complex in which a ligand is coordinated to a surface of a semiconductor nanoparticle. The semiconductor nanoparticle includes In and P, the ligand includes a mercapto fatty acid ester represented by the following general formula, and the mercapto fatty acid ester has an SP value of 9.30 or less.

General formula: HS—R.sub.1—COOR.sub.2 (where R.sub.1 is a C.sub.1-11 hydrocarbon group and R.sub.2 is a C.sub.1-30 hydrocarbon group). The present invention can provide a semiconductor nanoparticle complex that keeps high fluorescence quantum yield before and after purification.

A quantum dot-containing material includes: a quantum dot; and at least one ligand chemically bonded to the surface of the quantum dot and represented by a certain formula. A composition and an electronic apparatus, each include the quantum dot-containing material.

A quantum dot-containing material includes: a quantum dot; and at least one ligand chemically bonded to the surface of the quantum dot and represented by a certain formula. A composition and an electronic apparatus, each include the quantum dot-containing material.

A method of preparing a core-shell structured quantum dot particle includes the steps of (a) preparing a core of quantum dot particle containing indium (In) and phosphorus (P) and (b) forming a shell by reacting the core of the quantum dot particles prepared in step (a), a zinc oxo cluster represented by Formula 1 below, and at least one anion precursor containing a group 16 element. Quantum dot particles prepared by the method; a population of the quantum dot particles; and a display device containing the population of the quantum dot particles are disclosed:

##STR00001##

A method of preparing a core-shell structured quantum dot particle includes the steps of (a) preparing a core of quantum dot particle containing indium (In) and phosphorus (P) and (b) forming a shell by reacting the core of the quantum dot particles prepared in step (a), a zinc oxo cluster represented by Formula 1 below, and at least one anion precursor containing a group 16 element. Quantum dot particles prepared by the method; a population of the quantum dot particles; and a display device containing the population of the quantum dot particles are disclosed:

##STR00001##

The invention relates to scintillation inorganic oxide single crystals with garnet structure, which comprise cerium and are co-alloyed with titanium and Group 2 elements. The invention makes it possible to increase the scintillation output and to enhance the energy resolution of scintillation detectors during gamma-ray quantum registration. The technical result is achieved by a single crystal with a garnet structure being co-alloyed with cerium, titanium and Group 2 elements. This single crystal is produced by the Czochralski process.