JP2656841B2 - Light converter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a light converter for use in two-quantum light emission.

[Prior Art] A light converter that absorbs and excites incident light from a radiation source, converts the light to a longer wavelength than the incident light, and emits light is disclosed in Japanese Patent Application Laid-Open No. Sho 62-177604 and US Pat. No. 4,719,386 by the present inventors. There is already what is shown.

This light converter is expected as a new light converter that can have a higher luminous efficiency than a phosphor used for a general fluorescent lamp.

[Problems to be Solved by the Invention] By the way, emission and absorption (excitation) within the atomic structure (excitation level) of light are based on the rule of "Pauli's exclusion rule", and are basically within the range based on this rule. It is known that the light transition can occur only in a sequence unit having a difference of one between the principal quantum numbers (n). That is, n
Although the series is indicated by alphabets such as S, P, D, F... Corresponding to = 1, 2, 3, etc., it may be difficult to occur between S and D or between S and F.

 This transition process will be described using an example of a Na atom.

In the state where Na atoms are fixed in an atomic state, the desired two-quantum emission transition for photoexcitation by ultraviolet light of 254 nm obtained by mercury discharge is as shown in FIG. 6, and nP → nS or nP → nD Although non-emission transitions indicated by are conceivable in principle, they are unlikely to occur unless there is a chance to collide with each other, such as under gas, so they are stochastically small in a completely isolated and fixed state, and are mainly indicated by →. The transition to nS or nD occurs due to the light emission transition. However, since a light emission transition to another level indicated by → in FIG. 6 can also occur, the desired transition to nS or nD does not always occur 100%.

In the conventional example, no consideration is given to this point, and a transition condition with the highest efficiency and probability has not been established.

The present invention has been made in view of the above points, and an object of the present invention is to provide a light converter in which a transition probability is extremely high and two quantum luminescence can be obtained.

Means for Solving the Problems The present invention absorbs and excites incident light from a radiation source, converts the light into a longer wavelength than the incident light, and emits light, and is a base material of a light converter that transmits visible light. In the light converter, in which the light-emitting atoms have light emission characteristics substantially similar to the light emission characteristics of the atomic state, individually and fixed, the excitation level of the light-emitting atoms corresponding to the incident light and the light-emitting atoms surrounding the light-emitting atoms The diameter of a fine porous material having a diameter of not less than about one atom is formed so as to have a diameter at which a luminescent atom is fixed to a state having luminescent characteristics substantially similar to luminescent characteristics of an atomic state. The energy levels are shifted or broadened so that the excitation levels of adjacent series at the same energy level partially overlap.

[Operation] According to the present invention, when the adjacent series levels are superimposed, the non-light-emitting transition whose transition probability is considered to be zero occurs with a very large probability due to the superimposition and easily transitions. Two-quantum light emission can be obtained with higher efficiency than in the case of the excited state of atoms which are not superimposed almost as they are. That is, nP → nS or nP ← nS, nP → nD or nP ← nD is Paul
This is a light emission transition (not an electronic transition) permitted by the exclusion rule of ic, and there is almost no light emission transition between S and D and between 8 and F due to the forbidden relationship. However, when these levels partially overlap, electrons freely transition between them without light emission irrespective of the exclusion rule, and this probability is high. In the present invention, the atomic level between the levels where light emission transition cannot be performed by the exclusion rule is partially superimposed, and adjacent levels are partially overlapped with each other. Wake it up.

EXAMPLES The present invention will be described below with reference to examples.

First, the energy level diagram of the transition portion of the Na atom itself described above is a level having no or small jump width which can be drawn by an almost integral line as shown in FIG. 1 (a). .

The present invention has a modest atomic state (not in a perfect atomic state, and also in a compound or a molecular state in which some atoms and molecules are bonded to adjacent atoms, and of course, a slight interaction with each other with a very weak van der Waals force). By designing and processing to the extent that it has, a slight van der Waals bond (intermolecular attraction) between adjacent atoms and molecules occurs as shown in FIG. It is shifted or broadened slightly to superimpose the target excitation level nP and the equivalent energy excitation level (nS and nD or nD) of the adjacent series.

Here, the light converter of the present embodiment is formed based on, for example, a sol-gel thin film forming method.
The formation of the light converter by the sol thin film forming method will be briefly described.

First, water in which an appropriate amount of a metal salt of a desired light-emitting atom is mixed is mixed with alcohol at a ratio of 1: 1 or a ratio (volume ratio) around 1: 1. Ethoxysilane is used, and an equivalent amount or more of a silica base which is a parent substance of tetraethoxysilane and an appropriate amount of a base solution of a salt of a luminescent atom are added. The mixed solution is heated at room temperature or slightly to several hours to overnight. Stir. The sol is formed by the stirring process, and the liquid in which the sol is formed is applied and coated on a desired substrate (such as the inner surface of a glass tube of a lamp). The coated substrate is first fired at a high temperature in the air.

In this process, a matrix material composed of amorphous silica having a myriad of micro-sized porous materials (pores or vacancies) and metal salts are decomposed into the porous materials, and several hundred to 1000 ° C. in carbon monoxide and hydrogen. Secondary firing at high temperature. Here, it is needless to say that the calcining temperature history is set and managed in advance so that the diameter of the porous material containing the light-emitting atoms becomes a diameter at which the light-emitting atoms are fixed to a state substantially equivalent to the atomic state.

Thus, the film is reduced to only the light-emitting atoms, and is isolated and confined in the microporous amorphous silica to form a fixed film.

Here, the sintering temperature after reduction in the above forming process is adjusted to a temperature corresponding to a desired degree of energy shift. The sintering temperature determines the diameter d of the porous material that confines the light-emitting atoms, and the diameter d determines the degree of interaction between the light-emitting atoms and the adjacent host material, that is, the degree of energy shift.

FIG. 2 is a partial cross-sectional view of the light converter X of the present embodiment, in which light-emitting atoms 3 are isolated and fixed in a base material 2 sintered on a substrate 1.

FIG. 3 is a model diagram showing the state of formation of the light-emitting atoms 3 and the porous material 4. When the sintering temperature is low as shown in FIG. 3 (a), the diameter d of the porous material 4 is large. The energy shift and the broad are very small as shown in FIG. Conversely, if the sintering temperature is too high, as shown in FIG. 3 (c), the sintering is excessively reduced and the diameter d is reduced, and the interaction (intermolecular bonding force) with the adjacent base substance 2 is increased. (C)
And the energy shift and broadening are too large. FIG. 3 (b) shows a case where the sintering temperature is appropriately adjusted. In this case, the diameter d of the porous material 4 becomes an appropriate diameter, and the energy shift and broadness are also desired as shown in FIG. 4 (b). It will be. 4 (a) to 4 (c), A denotes a level to be absorbed / excited with respect to ultraviolet light, B denotes a level of the same energy of a series adjacent to the level A, and C denotes a ground level. . Here, for example, if level A is a P series,
B is an S sequence or a D sequence.

In order to confirm and adjust the optimum sintering temperature, as shown in FIG. 5, the specimen to be subjected to the pre-treatment is preliminarily sintered in the sintering furnace 7 as shown in FIG. Form X,
In this forming process, the optimum sintering temperature may be determined by observing the relationship between the sintering temperature and the intensity of the fluorescence spectrum using the variable wavelength laser 5 and the spectrometer 6. For example, when ultraviolet light is incident on a dye laser or the like, if the diameter d of the porous space is too small or too large, the first-stage excitation is insufficient, and the desired fluorescence emission is also insufficient. If the diameter is appropriate, strong light emission is obtained, so that the sintering temperature at this time is preferably adjusted and set as the sintering temperature during actual processing.

Incidentally, the light converter may be formed by a method other than the sol-gel thin film forming method, and in the case of using these forming methods, the optimum conditions are obtained by preliminary preliminary experiments as described above,
Actual processing may be performed based on this condition.

Thus, in the optical converter in which the excitation level and the equivalent energy excitation level of the adjacent series are superimposed by the energy shift and broadening, the non-light-emitting transition whose transition probability is considered to be zero is superimposed due to the superposition. Occurs at an extremely high probability. For example, when Na atoms are used as light-emitting atoms, transitions from nP to nS and nP to nD occur as shown in FIG.
High-efficiency two-quantum emission of nS → 3P → 3S or nD → 3P → 3S will occur.

The above energy shift can be used very effectively even when the original light emitting atoms themselves do not exactly match the excitation light and the excitation level. In other words, the excitation level band can be set to substantially the same energy level as the excitation light by the energy shift and the broad, and the absorption / excitation probability can be increased. By doing so, the range of available light-emitting atoms and excitation light sources can be broadened. If the energy shift or broadening is too large, not only the desired excitation level is superimposed but also the other excitation levels are superimposed, and the degree of unnecessary transition to them is increased. The quantum luminescence cannot be obtained with high efficiency.

〔The invention's effect〕

The present invention absorbs and excites incident light from a radiation source, converts the light into a longer wavelength than the incident light, and emits light.In the base material of the light converter that transmits visible light, the light-emitting atoms are in an atomic state. In the individually and individually fixed light converter having emission characteristics substantially similar to the emission characteristics of the above, the excitation level of the emission atoms corresponding to the incident light and about one atom surrounding the emission atoms are included. The diameter of the fine porous material is formed so as to have a diameter at which the light-emitting atoms are fixed to a state having light-emitting characteristics substantially similar to the light-emitting characteristics of the atomic state, and the diameter of the adjacent series having substantially the same energy level is formed. Since the energy level is shifted or broadened so that the excitation level partially overlaps with the excitation level, the non-emission transition whose transition probability is considered to be zero occurs with a very large probability due to the superposition and easily transitions. Will be superimposed There is an effect that higher efficiency in two quantum emitter can be obtained as compared with the case of the excitation level remains almost atomic no of and.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams for explaining the principle of the present invention.
Explanatory diagram of energy level of Na atom, energy level diagram of slightly shifted and broadened atomic Na atom, 2nd
FIG. 3 is a cross-sectional view of a light converter according to an embodiment of the present invention, and FIG.
FIGS. 4 (a) to 4 (c) are model diagrams of the generation state of the optical changer for explaining the sintering temperature adjustment, and FIGS. 4 (a) to 4 (c) are FIGS.
FIG. 5 is an energy shift model diagram of the immobilized issuing atoms corresponding to (c), FIG. 5 is an explanatory diagram of the sintering temperature adjustment setting of the above, and FIG. 6 is emission of Na atoms by ultraviolet light excitation by mercury discharge. It is a transition explanatory view. 1 is a substrate, 2 is a base substance, 3 is a light emitting atom, and X is a light converter.

Claims (1)

(57) [Claims] 1. A method of absorbing and exciting incident light from a radiation source, converting the light into a longer wavelength than the incident light, and emitting light. In the light converter, which has light emission characteristics substantially similar to the light emission characteristics of the state and is individually and independently fixed, the excitation level of the light emission atoms corresponding to the incident light and about one atom surrounding the light emission atoms are included. An adjacent series that has a microporous diameter greater than or equal to the diameter that is fixed so that the light-emitting atoms have a light-emitting property substantially similar to the light-emitting properties of the atomic state and has substantially the same energy level Characterized in that the energy levels are shifted or broadened so that the excitation levels partially overlap with each other.