WO2009157793A1

WO2009157793A1 - Method for controlling optical properties of nanocomposite materials

Info

Publication number: WO2009157793A1
Application number: PCT/RU2008/000397
Authority: WO
Inventors: Евгений Петрович ГРЕБЕННИКОВ
Original assignee: Grebennikov Evgeny Petrovich
Priority date: 2008-06-27
Filing date: 2008-06-27
Publication date: 2009-12-30

Abstract

The inventive method for controlling optical properties of nanocomposite materials consists in introducing into the structure of a nanocomposite material and linking in series to nanoparticles the following particles: intermediate bonding molecule particles which modify the spacial configuration when exposed to an external light action and bondable molecule particles which exhibit the optical properties thereof near nanoparticles, and in irradiating the nanocomposite material with light on wavelengths which modify the three-dimensional configuration of an intermediate bonding molecule.

Description

OPTICAL PROPERTIES MANAGEMENT METHOD

NANOCOMPOSITION MATERIALS

Technical field

The invention relates to nanotechnology and can be used to effectively manage the optical properties of nanocomposite materials used in nonlinear optics, information technology, in the development of optical memory, etc.

State of the art

The prior art method for controlling optical properties - luminescence by irradiating a luminescent material with infrared heat rays (G. S. Lansberg, Optics, M., "Hayka", 1976, S. 755). When the luminescent substance is heated, a rapid decrease in the intensity of the glow occurs. However, this method is inertial due to the finite values of the heat capacity and thermal conductivity of any substance and is practically not applicable for local dynamic control of the luminescence of nanocomposite materials.

Disclosure of invention

The invention is aimed at creating an effective method for controlling the optical properties of nanocomposite materials.

The solution to this problem is provided by the fact that in the method for controlling the optical properties of nanocomposite materials according to the invention, intermediate binder molecules — particles that change the spatial configuration under

SUBSTITUTE SHEET (RULE 26) external light, and the molecules being bound are particles with optical properties that are effectively manifested — changing near the nanoparticles, and irradiate the nanocomposite material with light at wavelengths that change the spatial configuration of the intermediate binder molecule.

The technical result, which consists in the possibility of efficient (fast, local and operational) control of the optical properties of nanocomposite materials, does not follow from the prior art and is due to the introduction of intermediate binder molecules into the nanocomposite material and the action of these intermediate binder molecules by light at wavelengths of which there is a change in their spatial configuration, mainly the length, and, accordingly, the distance between the nanoparticles, near which strong electromagnetic fields are realized, and with bound molecules - particles with optical properties that are effectively manifested - varying near nanoparticles. In this case, a change in the distribution occurs - distortion of the electromagnetic field of the bound molecules - particles with optical properties, which causes a change in the lifetime of the excited atoms and molecules of the latter, affects the rate of electronic transitions that determine the processes of absorption and spontaneous emission of light, and accordingly leads to a reversible change in the spectral characteristics and optical properties of these nanocomposite materials in general.

Embodiments of the invention

SUBSTITUTE SHEET (RULE 26) As nanoparticles of a nanocomposite material, when implementing the claimed method, metal, for example, gold, semiconductor or dielectric nanoparticles of a spherical, ellipsoidal, needle-shaped, rod-shaped, pyramidal or other shape, which achieves the greatest efficiency in changing the properties of the bound molecules, can be used.

Particles with luminescent, photochromic, polarizing, or other optical properties that are effectively manifested and change near nanoparticles (for example, cadmium selenide) can be used as bonded molecules.

As binders, which, due to the formation of chemical bonds, ensure the stability of the nanostructure, particles can be used that change the spatial configuration (for example, isomerize) when exposed to external light from a specific wavelength (photo-induced transition), for example, organic molecules with double bonds of the type carbon-carbon, carbon-nitrogen, nitrogen-nitrogen, capable of cis-trans isomerization (for example, azo dye molecules), or under the influence of an electric field (electrochromic transition e). To increase the difference in the lengths of the molecule in two forms (cis and trans states), it is possible to use successively two or more fragments capable of isomerization.

The claimed method of controlling the optical properties of a nanocomposite material is implemented as follows.

To obtain a nanocomposite material, binder molecules containing two are introduced into an aqueous suspension of nanoparticles with a diameter of 12–15 nm of colloidal gold in a ratio of 1: 12

SUBSTITUTE SHEET (RULE 26) the thio groups of azo dye particles of 4,4'-dithiomethylazobenzene, which change their spatial configuration due to the transition from the trans state to the cis state under the action of radiation at a wavelength of 365 nm and the reverse transition when exposed to visible light at a wavelength of 435 nm, while the molecule length - azo dye particles change from 9.5 nm to 5.5 nm and vice versa. When mixed on the surface of gold nanoparticles, a ligand shell is formed of binding molecules - azo dye particles. In the obtained system, in the same ratio to gold nanoparticles of 1: 12, an aqueous suspension of binderable molecules is added - colloidal particles of cadmium selenide (CdSe), whose optical properties are effectively influenced by gold nanoparticles (at a distance between CdSe particles and gold nanoparticles up to 10 nm the maximum photoluminescence enhancement of CdSe particles is up to 5 times, and at small distances of the order of 2 nm, photoluminescence is suppressed due to the resonant energy transfer from photoexcited CdSe quantum particles to metal particles - gold nanoparticles). In this case, the molecules bonded by molecules of cadmium selenide (CdSe) particles are deposited on the free thio groups of the ligand shell of the gold nanoparticles with the formation of macromolecules forming the spatial cluster structure of the nanocomposite material. The prepared suspension of the nanocomposite material is placed on a mirror glass substrate and dried to form a nanocomposite film.

In the process of controlling optical properties, the resulting nanocomposite material is irradiated for several seconds with radiation at a wavelength of 365 nm, which translates all

SUBSTITUTE SHEET (RULE 26) binding molecules - particles of azo dye to the cis state, in which the distance between the gold nanoparticles and the binding molecules - particles of cadmium selenide (CdSe) is 9.5 nm, which when excited (irradiation) of the nanocomposite material with light at a wavelength of 530 nm causes intense red luminescence at a wavelength of about 670 nm, which corresponds to a direct interband transition of bound molecules - cadmium selenide particles. To change the optical properties, the nanocomposite material capable of intense luminescence is irradiated for several seconds with light with a maximum radiation near 435 nm, which leads to the isomerization of binder molecules - azo dye particles (translation of molecules - azo dye particles into a trans state) and a decrease in the distance between gold nanoparticles and bound molecules - particles of cadmium selenide up to 5 nm. In this case, subsequent excitation of the nanocomposite material with light at a wavelength of 530 nm causes luminescence, but its intensity decreases by several tens of times. Upon repeated irradiation with light at a wavelength of 365 nm, the ability of the nanocomposite material to intense red luminescence under the influence of exciting radiation at a wavelength of 530 nm is completely restored.

The claimed method provides operational and local (pointwise) control of the optical properties of the nanocomposite material as follows.

The nanocomposite material is preliminarily uniformly irradiated with light at a wavelength of 435 nm, which transfers the binding molecules — particles of the azo dye, into the trans state. Then this nanocomposite material, characterized by low

SUBSTITUTE SHEET (RULE 26) the intensity of luminescence, is irradiated locally with spotlight through a mask of holes with a diameter of 0.3 mm for a tenth of a second by focused radiation at a wavelength of 365 nm, converting the binding molecules - particles of azo dye to the cis state only in places corresponding to the distribution of holes in the mask and irradiated . When the nanocomposite material is uniformly excited by light at a wavelength of 530 nm, a point luminescence pattern arises, which exactly repeats the mask. Such a mask-like luminescence dot pattern remains in the dark for an unlimited time and can be reproduced at any time by excitation at a wavelength of 530 nm or erased by subsequent uniform exposure to radiation at a wavelength of 365 nm or 435 nm.

Thus, the claimed method provides effective operational and point-by-point control of the optical properties of nanocomposite materials, which makes it technically possible to use it for optical recording and reading of information, in the development of chameleon coatings, in nonlinear optics, etc.

SUBSTITUTE SHEET (RULE 26)

Claims

Claim

A method for controlling the optical properties of nanocomposite materials, characterized in that intermediate binder molecules — particles that change the spatial configuration under external light exposure — are introduced and sequentially connected to the nanoparticles, and the molecules to bind are particles with optical properties that appear near the nanoparticles and are irradiated nanocomposite material with light at wavelengths that change the spatial configuration of the intermediate binder molecule.

SUBSTITUTE SHEET (RULE 26)