Abstract: The present invention provides metal fine particles which have selective wavelength absorption characteristics in a wavelength region from visible light to near infrared light, and have sharp absorption characteristics, and influences little the surrounding wavelength, and therefore, they yield tones having high chroma. The present invention provides metal fine particles wherein an aspect ratio is in a range from 1.1 to 8.0, a maximum absorption wavelength in plasmon absorption is in a range from 400 nm to 1,200 nm, and an absorption coefficient at a peak position of the maximum absorption wavelength is in a range from 6,000 to 20,000 L/mol·cm (measurement concentration: 1.6×10?4 mol/L, and solvent: water).

Abstract: A method for manufacturing metal nanorods includes: a step of adding a reducing agent to a metallic salt solution; a step of radiating light into the metallic salt solution containing the reducing agent; and a step of leaving the light-radiated metallic salt solution containing the reducing agent stationary in a dark place so as to grow metal nanorods. Metal nanorods can be also grown by forming a mixed solution by fractionating the above light-radiated metallic salt solution and mixing the fractionated metallic salt solution into a non-radiated metallic salt solution containing the reducing agent, or mixing a non-radiated metallic salt solution and the reducing agent into the above light-radiated metallic salt solution; and leaving the mixed solution stationary in a dark place so as to grow metal nanorods.

Abstract: A process for producing metallic fine particles is provided by, the reduction of the metallic ions performed in two steps using two types of reducing agents which significantly differ in reducing ability thereof, in which a reducing agent in which the reduction ability is strong is used in the first reduction step, and a reducing agent in which the reduction ability is weak is used in the second reduction step, and the nano-sized metallic fine particles are produced. An aqueous metallic salt solution containing a surfactant is used and a two-step reduction is performed in the same vessel, in which as the reducing agent of the first reduction process, at least one selected from the group consisting of boron hydride, dimethylamine borane, hydrazine, and ascorbic acid is used, and as the reducing agent of the second reduction process, specific alkylamine or alkanolamine is used.

Abstract: The present invention provides metal fine particles which have selective wavelength absorption characteristics in a wavelength region from visible light to near infrared light, and have sharp absorption characteristics, and influences little the surrounding wavelength, and therefore, they yield tones having high chroma. The present invention provides metal fine particles wherein an aspect ratio is in a range from 1.1 to 8.0, a maximum absorption wavelength in plasmon absorption is in a range from 400 nm to 1,200 nm, and an absorption coefficient at a peak position of the maximum absorption wavelength is in a range from 6,000 to 20,000 L/mol·cm (measurement concentration: 1.6×10?4 mol/L, and solvent: water).

Abstract: A method for manufacturing metal nanorods includes: a step of adding a reducing agent to a metallic salt solution; a step of radiating light into the metallic salt solution containing the reducing agent; and a step of leaving the light-radiated metallic salt solution containing the reducing agent stationary in a dark place so as to grow metal nanorods. Metal nanorods can be also grown by forming a mixed solution by fractionating the above light-radiated metallic salt solution and mixing the fractionated metallic salt solution into a non-radiated metallic salt solution containing the reducing agent, or mixing a non-radiated metallic salt solution and the reducing agent into the above light-radiated metallic salt solution; and leaving the mixed solution stationary in a dark place so as to grow metal nanorods.

Abstract: A method for manufacturing metal nanorods includes: a step of adding a reducing agent to a metallic salt solution; a step of radiating light into the metallic salt solution containing the reducing agent; and a step of leaving the light-radiated metallic salt solution containing the reducing agent stationary in a dark place so as to grow metal nanorods. Metal nanorods can be also grown by forming a mixed solution by fractionating the above light-radiated metallic salt solution and mixing the fractionated metallic salt solution into a non-radiated metallic salt solution containing the reducing agent, or mixing a non-radiated metallic salt solution and the reducing agent into the above light-radiated metallic salt solution; and leaving the mixed solution stationary in a dark place so as to grow metal nanorods.

Abstract: A process for producing metallic fine particles is provided by, the reduction of the metallic ions performed in two steps using two types of reducing agents which significantly differ in reducing ability thereof, in which a reducing agent in which the reduction ability is strong is used in the first reduction step, and a reducing agent in which the reduction ability is weak is used in the second reduction step, and the nano-sized metallic fine particles are produced. An aqueous metallic salt solution containing a surfactant is used and a two-step reduction is performed in the same vessel, in which as the reducing agent of the first reduction process, at least one selected from the group consisting of boron hydride, dimethylamine borane, hydrazine, and ascorbic acid is used, and as the reducing agent of the second reduction process, specific alkylamine or alkanolamine is used.

Abstract: This method for manufacturing metal fine particles includes using an aqueous solution containing an amine having a reducing capacity and an ammonium salt having substantially no reducing capacity so as to reduce metal ions with said amine in a presence of said ammonium salt, thereby manufacturing rod-shaped metal fine particles. This metal fine particles are manufactured by this method for manufacturing metal fine particles, and have a major axis of 400 nm or less, a minor axis of 15 nm or less, and an aspect ratio of more than 1.

Abstract: This method for manufacturing metal fine particles includes using an aqueous solution containing an amine having a reducing capacity and an ammonium salt having substantially no reducing capacity so as to reduce metal ions with said amine in a presence of said ammonium salt, thereby manufacturing rod-shaped metal fine particles. This metal fine particles are manufactured by this method for manufacturing metal fine particles, and have a major axis of 400 nm or less, a minor axis of 15 nm or less, and an aspect ratio of more than 1.

Abstract: The present invention provides metal fine particles which have selective wavelength absorption characteristics in a wavelength region from visible light to near infrared light, and have sharp absorption characteristics, and influences little the surrounding wavelength, and therefore, they yield tones having high chroma. The present invention provides metal fine particles wherein an aspect ratio is in a range from 1.1 to 8.0, a maximum absorption wavelength in plasmon absorption is in a range from 400 nm to 1,200 nm, and an absorption coefficient at a peak position of the maximum absorption wavelength is in a range from 6,000 to 20,000 L/mol·cm (measurement concentration: 1.6×10?4 mol/L, and solvent:water).

Abstract: A method for manufacturing metal nanorods includes: a step of adding a reducing agent to a metallic salt solution; a step of radiating light into the metallic salt solution containing the reducing agent; and a step of leaving the light-radiated metallic salt solution containing the reducing agent stationary in a dark place so as to grow metal nanorods. Metal nanorods can be also grown by forming a mixed solution by fractionating the above light-radiated metallic salt solution and mixing the fractionated metallic salt solution into a non-radiated metallic salt solution containing the reducing agent, or mixing a non-radiated metallic salt solution and the reducing agent into the above light-radiated metallic salt solution; and leaving the mixed solution stationary in a dark place so as to grow metal nanorods.