JP3605642B2 - Photochemical hole burning media - Google Patents

Description

【００４０】
Ｍｅ_３ＳｉＳｉＭｅ_３あるいはクラウンエーテルを入れない試料についても同様の方法で作成した。
【００４１】
また、同様の方法により、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^３＋，Ｍｅ_３ＳｎＳｎＭｅ_３を得た。
【００４２】
ホールバーニング特性については、ローダミン６Ｇ色素レーザーを用いてホールを形成させ測定した。また、温度サイクル実験は７７Ｋでホールを形成させた後、１００、１５０、２００、２５０および３００Ｋと順次温度を上げた後約１分間保持し、再び７７Ｋに戻して励起スペクトルを測定することで行った。
【００４３】
ＳｉＯ_２：Ｅｕ（１５Ｃ５）^３＋，Ｍｅ_３ＳｉＳｉＭｅ_３およびＳｉＯ_２：Ｅｕ^３＋，Ｍｅ_３ＳｉＳｉＭｅ_３の７７Ｋにおけるレーザー照射前後の励起スペクトルとその差スペクトルを図４（ａ）および（ｂ）に示す。
【００４４】
照射前の試料では、５７９−５８１ｎｍの波長領域にＥｕ^３＋イオンの^７Ｆ_０−^５Ｄ_０の遷移に対応する励起スペクトルが観察された。これらのスペクトルにローダミン６Ｇ色素レーザーを１００ｍＷ／ｍｍ^２で６００秒間照射したところ、図に示すように半値幅０．１２５ｎｍのホールが観察された。
【００４５】
クラウンエーテルの入っていないものについては、レーザーを照射してもスペクトル全体の発光強度が単に減少するのみでホールは形成されなかった。このことから、マトリックス中では単独のＥｕ^３＋イオンよりもクラウンエーテルと錯形成したＥｕ^３＋イオンの方が励起状態においてＭｅ_３ＳｉＳｉＭｅ_３から電子を受け取り易く、これにより効率良くホールを形成できることが明らかになった。
【００４６】
ＳｉＯ_２：Ｅｕ（１５Ｃ５）^３＋，Ｍｅ_３ＳｎＳｎＭｅ_３についてもスペクトルを観察した。ＳｉＯ_２：Ｅｕ（１５Ｃ５）^３＋，Ｍｅ_３ＳｎＳｎＭｅ_３の７７Ｋにおけるレーザー照射前後の励起スペクトルとその差スペクトルを図５に示す。
【００４７】
その結果、Ｍｅ_３ＳｎＳｎＭｅ_３についてもクラウンエーテルの入っているものについてはホールの形成が確認された（半値幅は、０．１４１ｎｍ）。クラウンエーテルの入っていないものについては、ホールは形成されなかった。したがって、マトリックス中では単独のＥｕ^３＋イオンよりもクラウンエーテルと錯形成したＥｕ^３＋イオンの方が励起状態においてＭｅ_３ＳｎＳｎＭｅ_３から電子を受け取り易く、これにより効率良くホールを形成できることが明らかになった。
【００４８】
実施例４
次に、本発明の一実施態様の光化学ホールバーニング媒体について、温度サイクル特性を調べた。
【００４９】
まず、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}Ｍｅ_３ＳｉＳｉＭｅ_３、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}Ｍｅ_３ＳｎＳｎＭｅ_３、及びＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}を作成した。ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}Ｍｅ_３ＳｎＳｎＭｅ_３については、Ｍｅ_３ＳｉＳｉＭｅ_３の代わりにＭｅ_３ＳｎＳｎＭｅ_３を用いる以外、また、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}については、電子供与性有機化合物を使用しない事以外、実施例３と同様の方法を用いて作成した。
【００５０】
これらについて温度サイクル特性を調べた。即ち、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^３＋，Ｍｅ_３ＳｉＳｉＭｅ_３およびＳｉＯ_２：Ｅｕ（１５Ｃ５）^３＋・Ｍｅ_３ＳｎＳｎＭｅ_３における７７Ｋで形成させたホールの７７−３００Ｋにおける温度サイクル特性を調べた。結果を図６に示す。図６（ａ）は、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}Ｍｅ_３ＳｉＳｉＭｅ_３の温度サイクル特性を示す図である。図６（ｂ）は、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}Ｍｅ_３ＳｎＳｎＭｅ_３の温度サイクル特性を示す図である。図６（ｃ）は、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}の温度サイクル特性を示す図である。
【００５１】
ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}Ｍｅ_３ＳｉＳｉＭｅ_３については、３００Ｋまでホールが保持された。ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}Ｍｅ_３ＳｎＳｎＭｅ_３については、２５０Ｋまでホールが保持された。
【００５２】
温度の上昇と共に均一幅は広がり、ホールの深さは減少するものの、３００ＫでＭｅ_３ＳｉＳｉＭｅ_３を含む場合、０．４７９ｎｍの半値幅で、深さが７７Ｋのものの約７０％となるホールが保持された。２５０ＫのＭｅ_３ＳｎＳｎＭｅ_３では０．４７４ｎｍの半値幅と７７Ｋのそれのおよそ６１％のホール深さが保持された。したがって、還元剤を加えた媒体は、クラウンエーテル錯体のみのものと比較してホールの温度安定性が向上していることが分かる。これは、還元剤として機能するＭｅ_３ＭＭＭｅ_３を（Ｍ＝Ｓｉ又はＳｎ）導入することで、還元に伴いＭ−Ｍ結合が開裂し逆反応が起こりにくくなったためと考えられる。
【００５３】
実施例５
次に、還元剤の濃度を変化させて温度サイクル特性を調べた。試料の作製は、実施例３に記載された方法にしたがった。還元剤として、Ｍｅ_３ＳｉＳｉＭｅ_３を用いた。
【００５４】
温度サイクル特性の結果を、図７に示す。図７は、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}Ｍｅ_３ＳｉＳｉＭｅ_３の温度サイクル特性を示す。図７（ａ）は、３ｍｏｌ％のＭｅ_３ＳｉＳｉＭｅ_３を用いた場合、図７（ｂ）は、６ｍｏｌ％のＭｅ_３ＳｉＳｉＭｅ_３を用いた場合を、それぞれ示す。
【００５５】
図７から明らかなように、６ｍｏｌ％のＭｅ_３ＳｉＳｉＭｅ_３を用いた場合の方が、３ｍｏｌ％のものよりホールの安定性が高いことが分かる。これは、Ｍｅ_３ＳｉＳｉＭｅ_３の増加によって、還元されるＥｕ（１５Ｃ５）^{３ ＋}の量が増加し、ホールがそれだけ戻りにくくなったためと考えられる。
【００５６】
実施例６
次に、固体マトリックスを変化させた場合のスペクトルを調べた。固体マトリックスとして、ＳｉＯ_２に、Ａｌ_２Ｏ_３、ＴｉＯ_２、ＺｒＯ_２、又はＴａ_２Ｏ_５を導入したものを用いた。実施例１に記載の方法により、同様に試料を作製した。
【００５７】
これらの試料について、レーザー照射し、励起スペクトルを観察した。図８は、ＳｉＯ_２−ＭｘＯｙ（Ｓｉ：Ｍ＝７：３）：［Ｅｕ（１５Ｃ５）］^３＋（Ｅｕ^３＋：１５Ｃ５＝１：３）の７７Ｋにおけるレーザー照射前後の励起スペクトルを示す。
【００５８】
いずれの場合も生成したホールの深さは、ＳｉＯ_２単独と比べて顕著な違いは見られなかった。
【００５９】
ホール幅に関しては、ＳｉＯ_２にＡｌ_２Ｏ_３を導入した場合、Ａｌ^３＋が非架橋酸素と結合し［ＡｌＯ_４］としてネットワークを形成する。これによって、Ｅｕ^３＋イオン近傍の局所構造が強化され、ホール幅が狭くなる。ＺｒＯ_２及びＴａ_２Ｏ_５を導入した場合にも、同様の効果があると考えられる。
【００６０】
これに対して、ＳｉＯ_２にＴｉＯ_２を導入した場合、ＳｉＯ_２よりもホール幅が広がる傾向を示した。これは、［ＴｉＯ_４］は、非架橋酸素よりも架橋酸素と結合すると考えられるからである。
【００６１】
次に、これらの温度サイクル特性を調べた。図９及び図１０は、ＳｉＯ_２−Ｍ_ｘＯ_ｙ：［Ｅｕ（１５Ｃ５）］^３＋の７７Ｋで生成したホールの温度サイクル特性を示す。
いずれも室温までの温度サイクル後もホールが確認された。特に、ＺｒＯ_２及びＴａ_２Ｏ_５を導入した場合には、Ａｌ_２Ｏ_３を導入した場合よりも室温で深いホールが残存した。
【００６２】
いずれの固体マトリックスを用いた場合にも、高温で高いホール安定性を示した。これは、Ｅｕ^３＋イオン近傍の局所構造が強化されたこと、及び重い元素を加えることによる格子振動が抑制されたこと等によるものと考えられる。
【００６３】
実施例７
実施例１と同様に光化学ホールバーニング媒体を作製し、還元剤としてインデンを用いたことを除き、実施例３と同様にホールバーニング特性を評価した。
ＳｉＯ_２：Ｅｕ（１５Ｃ５）^３＋、インデンの７７Ｋにおけるレーザー照射前後の励起スペクトルとその差スペクトルを図１１に示す。
この結果、ホールの形成が確認された。この結果から、インデンの酸化還元電位と同等あるいは低いものであれば、還元剤として良好に機能し、安定したホールを形成することが分かる。ここで、有機分子の酸化還元電位について以下の表２にまとめる。
【表２】

表２に挙げる還元剤は、いずれもインデンの酸化還元電位よりも低いので良好な光化学ホールバーニング特性を与えることが分かる。
【００６４】
【発明の効果】
本発明のホールバーニング媒体によれば、照射するレーザー光の波長に応じて信号を書き込むことができるという有利な効果を奏する。
【００６５】
また、本発明のホールバーニング媒体によれば、室温で動作可能な波長多重型光メモリを実現できるという有利な効果を奏する。
【図面の簡単な説明】
【図１】レーザー光照射前後のＳｉＯ_２−ＺｒＯ_２：［Ｅｕ（１５Ｃ５）］^３＋の励起スペクトルを示す図である。
【図２】ＳｉＯ_２−ＺｒＯ_２：［Ｅｕ（１５Ｃ５）］^３＋の温度サイクル特性を示す図である。図２（ａ）がＳｉＯ_２−ＺｒＯ_２ ＝７：３の場合、図２（ｂ）がＳｉＯ_２−ＺｒＯ_２ ＝５：５の場合、図２（ｃ）がＳｉＯ_２−ＺｒＯ_２＝３：７の場合を、それぞれ示す。
【図３】レーザー光照射前後のＳｉＯ_２：［Ｅｕ（１５Ｃ５）］^３＋の蛍光スペクトルを示す図である。
【図４】本発明の一実施態様の光化学ホールバーニング媒体について、レーザー照射前後におけるスペクトルを示す。
【図５】本発明の一実施態様の光化学ホールバーニング媒体について、レーザー照射前後におけるスペクトルを示す。
【図６】本発明の一実施態様の光化学ホールバーニング媒体について、温度サイクル特性を示す。（ａ）は、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}Ｍｅ_３ＳｉＳｉＭｅ_３の温度サイクル特性を示す図である。（ｂ）は、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}Ｍｅ_３ＳｎＳｎＭｅ_３の温度サイクル特性を示す図である。（ｃ）は、ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}の温度サイクル特性を示す図である。
【図７】ＳｉＯ_２：Ｅｕ（１５Ｃ５）^{３ ＋}Ｍｅ_３ＳｉＳｉＭｅ_３の温度サイクル特性を示す。（ａ）は、３ｍｏｌ％のＭｅ_３ＳｉＳｉＭｅ_３を用いた場合、（ｂ）は、６ｍｏｌ％のＭｅ_３ＳｉＳｉＭｅ_３を用いた場合を、それぞれ示す。
【図８】ＳｉＯ_２−Ｍ_ｘＯ_ｙ（Ｓｉ：Ｍ＝７：３）：［Ｅｕ（１５Ｃ５）］^３＋（Ｅｕ^３＋：１５Ｃ５＝１：３）の７７Ｋにおけるレーザー照射前後の励起スペクトルを示す。
【図９】ＳｉＯ_２−Ｍ_ｘＯ_ｙ：［Ｅｕ（１５Ｃ５）］^３＋の７７Ｋで生成したホールの温度サイクル特性を示す。
【図１０】ＳｉＯ_２−Ｍ_ｘＯ_ｙ：［Ｅｕ（１５Ｃ５）］^３＋の７７Ｋで生成したホールの温度サイクル特性を示す。
【図１１】ＳｉＯ_２：Ｅｕ（１５Ｃ５）^３＋、インデンの７７Ｋにおけるレーザー照射前後の励起スペクトルとその差スペクトルを示す。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical memory that provides wavelength multiplexing type high density recording, and more particularly to a photochemical hole burning medium.
[0002]
[Prior art]
Optical recording media capable of rewriting recorded information with other information can be roughly classified into a heat mode type and a photon mode type based on the operation principle. The former reversibly changes between different optically identifiable states (recorded state / erased state) using a heating / cooling process of the medium by laser light irradiation, and includes a magneto-optical medium, a phase change medium, Organic media and the like belong to this. The latter excites a reversible optical change by directly using the inherent energy of light determined by the wavelength, and includes a photochromic medium and a photochemical hole burning (PHB) medium.
[0003]
Persistent Spectral Hole Burning (PSHB) is a method in which a solid in which molecules or ions having light absorption are dispersed is irradiated with laser light, so that a depression (hole) is permanently formed in the spectrum at the same wavelength position as the irradiation light. Is a phenomenon that occurs in Hole burning is an effective means for high-resolution spectroscopy in solids, and if the hole width (uniform width) is narrower than the absorption spectrum width (nonuniform width), application as a wavelength multiplexing type high density optical memory can be expected. . That is, by performing hole burning while changing the wavelength of the irradiation laser, a plurality of mutually independent holes can be formed at one spot. Wavelength multiplexing recording can be realized by associating bits of 1 and 0 with the presence or absence of this hole, so that an ultra-high density optical memory can be realized. As a material for such an optical memory, a material into which rare earth ions are introduced is known.
[0004]
[Problems to be solved by the invention]
However, currently, a medium at or near a practical level is of a heat mode type. In the heat mode type, recording is performed using light of a single wavelength, and the recording capacity is limited.
[0005]
The photon mode type is at a basic material search level. Of the photon mode type, the photochemical hole burning medium has the advantage that the recording capacity can be dramatically increased by overwriting information at different wavelengths in one place using the phenomenon called hole burning. is there. However, the photochemical hole burning medium is at a basic material search level, including the above-mentioned materials into which rare earth ions have been introduced, and a suitable material for the photochemical hole burning medium is in the research stage. Therefore, development of a material that can be used for a photochemical hole burning medium has been desired.
[0006]
Therefore, an object of the present invention is to provide a photochemical hole burning medium capable of dramatically increasing the recording capacity.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors have conducted intensive studies on a material in which various complexes are dispersed in a SiO ₂ matrix, and as a result, have found a material that can retain holes even at room temperature.
[0008]
The photochemical hole burning medium of the present invention is characterized by comprising a material in which a rare earth complex and a reducing agent are dispersed in a solid matrix.
[0009]
In a preferred embodiment of the photochemical hole burning medium of the present invention, the rare earth complex is at least selected from the group consisting of a europium (III) crown ether complex, a europium (III) polyether complex, and a europium (III) cryptand complex. It is characterized by one kind.
[0010]
Further, as a preferred embodiment of the photochemical hole burning medium of the present invention, a rare earth complex that contributes to the formation of holes, and a reducing property that contributes to the stability of holes, that is, an electron-donating organic molecule is uniformly dispersed in a dispersed state. It is a retained electron donating organic compound.
[0011]
In a preferred embodiment of the photochemical hole burning medium of the present invention, the electron-donating organic composite compound is a silane compound.
[0012]
Further, as a preferred embodiment of the photochemical hole burning medium of the present invention, a silane or disilazane compound is a group consisting of hexaalkyldisilazane represented by hexamethyldisilazane or hexaalkyldisilazane represented by hexamethyldisilazane. At least one selected from the group consisting of:
[0013]
In a preferred embodiment of the photochemical hole burning medium of the present invention, the electron donating organic compound is an organic tin compound.
[0014]
In a preferred embodiment of the photochemical hole burning medium of the present invention, the organotin compound is a compound represented by RSnSnR (where R represents an alkyl group or an aryl group). .
[0015]
In a preferred embodiment of the photochemical hole burning medium of the present invention, the solid matrix is at least one selected from the group consisting of glass-forming compounds represented by silica, germanium oxide, boron oxide, phosphorus pentoxide, and tellurium oxide. It is a seed.
[0016]
In a preferred embodiment of the photochemical hole burning medium of the present invention, the solid matrix further includes Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , TiO ₂ , ZrO ₂ , Nb ₂ O _5, and Ta _2. characterized in that from the group consisting of O ₅ containing at least one selected.
In a preferred embodiment of the photochemical hole burning medium of the present invention, the redox potential of the reducing agent is 1.5 V (vs. SCE) or less.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
The photochemical hole burning medium of the present invention comprises a material in which a rare earth complex and a reducing agent are dispersed in a solid matrix. The present invention is a photochemical hole burning medium using a material exhibiting a photochemical hole burning phenomenon.
[0018]
In the present invention, the solid matrix means a host molecule of a photochemical hole burning medium, and is not particularly limited. For example, examples of the solid matrix include at least one selected from the group consisting of glass-forming compounds represented by silica, germanium oxide, boron oxide, phosphorus pentoxide, and tellurium oxide. The solid matrix may further include at least one selected from the group consisting of Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , TiO ₂ , ZrO ₂ , Nb ₂ O _5, and Ta ₂ O _5. Can be included. As a solid matrix, silica can be mentioned from the viewpoint that it can be easily prepared using a sol-gel method.
[0019]
Examples of the rare earth complex include at least one selected from the group consisting of a europium (III) crown ether complex, a europium (III) polyether complex, and a europium (III) cryptand complex.
[0020]
The rare earth complex is preferably a europium (III) crown ether complex, from the viewpoint that reduction to divalent, which is considered to be one of the causes of the photochemical hole burning effect, is likely to occur. A macrocyclic compound represented by a crown ether is a macrocyclic compound having a heteroatom such as oxygen, nitrogen, or sulfur as an electron-donating (donor) atom, and is 12-crown-4,15-crown-5,18-. Crown-6, 24-crown-8, dibenzo-18-crown-6, cryptand [2.2], cryptand [2.2.2] and the like can be mentioned. In the present invention, these macrocyclic compounds can be used.
[0021]
As the crown ether, 15-crown-5 (hereinafter, referred to as 15C5) is preferable as the crown ether from the viewpoint that bivalent europium ions are easily complexed.
[0022]
The rare earth metal is not particularly limited, and examples thereof include Eu, Sm, and Pr. From the viewpoint of being easily reduced to divalent, Eu can be preferably used as the rare earth metal.
[0023]
Further, the reducing agent used in the present invention is not particularly limited as long as the rare earth ion is easily reduced, no reverse reaction occurs, and the absorption does not overlap with the zero phonon line of the rare earth ion. A molecular organic compound having an affinity can be given. From the viewpoint that electrons can be easily transferred by the rare earth ion, the reducing agent preferably includes a silane or disilazane compound and an organotin compound.
[0024]
Examples of the silane or disilazane compound include at least one selected from the group consisting of hexaalkyldisilane represented by hexamethyldisilane and hexaalkyldisilazane represented by hexamethyldisilazane. Among these, from the viewpoint of being easily soluble in a general solvent used for the sol-gel reaction, hexamethyldisilane can be mentioned as the silane compound, and hexamethyldisilazane can be mentioned as the disilazane compound.
[0025]
Examples of the organotin compound include a compound represented by RSnSnR (where R represents an alkyl group or an aryl group). Preferably, R is a methyl group from the viewpoint of being easily soluble in a general solvent used for the sol-gel reaction.
[0026]
The amount of the reducing agent varies depending on the rare earth ion, the complex ligand, the solid matrix, and the like used, and is not particularly limited.From the viewpoint of maintaining high hole stability, the amount of the reducing agent is based on the amount of the metal component constituting the solid matrix. The ratio can be up to 〜20 mol%. From the viewpoints of transparency and translucency of the medium, the content is preferably 3 to 6 mol%.
In a preferred embodiment of the present invention, the redox potential of the reducing agent is about 1.5 V (vs. SCE) or less in an organic solvent. This is because the oxidation potential of Eu ³⁺ / Eu ²⁺ is approximately −0.43 V (vs. NHE) in an aqueous solution, becomes excited by laser light irradiation, and the redox potential of the reducing agent becomes 1.5 V (vs. SCE). This is because if it is below, it can be reduced to Eu ²⁺ . Further, by using a reducing agent having such a redox potential, rare earth ions of the complex compound can be effectively reduced.
Therefore, a reducing organic molecule in which the redox potential of the reducing agent is smaller than about 1.5 V (vs. SCE) can be theoretically reduced to Eu ^2+, and can exhibit hole burning.
In addition, since a substance having an oxidation-reduction potential of 1.5 or more can form a hole in relation to another rare-earth complex, an organic substance having an oxidation-reduction potential of about 1.5 V (vs. SCE) or more is used in such a case. Molecules can be used.
[0027]
Next, a method for producing the photochemical hole burning medium of the present invention will be described. The photochemical hole burning medium of the present invention can be produced by, for example, a conventional sol-gel method. The sol-gel method generally refers to a method in which a hydrous oxide sol is dehydrated to form a gel, and the gel is heated and dried to prepare an inorganic oxide or the like as a thin film or a thick film on a certain shape or a substrate. .
[0028]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not intended to be construed as being limited to the following examples.
[0029]
Example 1
First, a photochemical hole burning medium using a solid matrix in which ZrO ₂ was added to SiO ₂ was produced by a sol-gel method. The creation procedure is as follows. A few drops of hydrochloric acid as a catalyst were added to a solution of Si (OC ₂ H ₅ ) ₄ : H ₂ O: C ₂ H ₅ OH = 1: 1: 5 (molar ratio), and the mixture was further refluxed for 1 hour. Thereafter, a metal alkoxide Zr (OC ₂ H ₅ ) ₄ was added to the solution such that Si: Zr = 7: 3, 5: 5, 3: 7, and the mixture was refluxed for another hour. _{EuC1 3: H 2 O: C} 2 H 5 OH: 15C5 = 0.03: 4: 4: 0.03 was added, further 2 weeks at 50 ° C., dried for 2 days at 90 ° _C., (SiO 2 -ZrO ₂ ): [Eu (15C5)] ³⁺ was obtained.
[0030]
The holes were formed by cooling the sample using a cryostat and then irradiating a rhodamine 6G dye laser beam of 100 mW / mm ² for 10 minutes. The stability of the hole was evaluated based on a temperature cycle in which the sample in which the hole was formed at 77K was heated to a predetermined temperature, held for about 1 minute, and then cooled again to 77K.
More specifically, a sample in which 3 mol% of EuCl ₃ and 9 mol% of 15-crown-5 (15C5) are introduced into a ceramic in which SiO ₂ and ZrO ₂ are mixed at a predetermined ratio is irradiated with a laser beam at 77K. In particular, a hole was formed.
[0031]
These samples, ⁷ F ₀ before and after the laser irradiation - shows the excitation spectrum of the ⁵ D ₀ in FIG.
[0032]
As a result, as the amount of ZrO ₂ in the solid matrix increased, the non-uniform width was expanded. It is considered that the local structure near Eu ³⁺ ions in the matrix became non-uniform due to the introduction of ZrO _2. Can be However, the depth of the formed hole became shallower with an increase in the amount of ZrO ₂ introduced. In addition, when SiO ₂ : ZrO ₂ = 5: 5, anti-holes were observed, which is considered to be due to the formation of a strong network, which inhibited the complex formation between Eu ³⁺ ions and 15C5.
[0033]
FIG. 2 shows the temperature cycle characteristics of (SiO ₂ —ZrO ₂ ): Eu (15C5) ^{3 +} in which holes were formed at 77K. FIG. 2A shows the case where SiO ₂ -ZrO ₂ = 7: 3, FIG. 2B shows the case where SiO ₂ -ZrO ₂ = 5: 5, and FIG. 2C shows the case where SiO ₂ -ZrO ₂ = 3: 7 is shown.
[0034]
When the components constituting the matrix were SiO ₂ -ZrO ₂ = 7: 3, holes could be held up to 300K. In the case of SiO ₂ -ZrO ₂ = 5: 5, holes could be held up to 150K. When SiO ₂ -ZrO ₂ = 3: 7, holes could be held up to 100K. From this, it has been clarified that the addition of a high concentration of ZrO ₂ increases the non-uniform width, but decreases the hole generation efficiency, and makes it impossible to hold holes at high temperatures.
Similar _{results, SiO 2 -Al 2 O 3,} SiO 2 -Ga 2 O 3, SiO 2 -In 2 O 3, SiO 2 -TiO 2, SiO 2 -Nb 2 O 5 and _SiO 2 _-Ta 2 _{O 5} Was also found in the matrix of each system.
[0035]
Example 2
Next, in order to elucidate the cause of the high hole holding temperature of the above-mentioned composite glass, a strength of 300 mWmm ⁻ at room temperature for SiO ₂ : [Eu (15C5)] ^{3 +} (EuCl ₃ = 3 mol%, 15C5 = 9 mol%) ^2. Irradiation was carried out with an R6G laser beam having a wavelength of 579.6 mm for 2 hours, and the fluorescence spectra before and after the irradiation were examined. The result of the fluorescence spectrum is shown in FIG. As a result, in the sample after laser irradiation, reduces the emission intensity of 570~720nm based on ^{Eu 3+} ions, fluorescent peak based on ^{Eu 2 +} ions was found that appears newly in the vicinity of 420 nm.
[0036]
Therefore, the light reduction of ^{Eu 3+} ions by laser irradiation as PSHB mechanism to ^{Eu 2 +} ions was suggested.
[0037]
Example 3
From the results described in Example 2, it is reduced from the Eu ³⁺ ions to Eu ^{2 +} ions, it has been found capable of expressing the better hole retention characteristics.
Therefore, it was attempted to disperse various reducing agents together with the rare earth complex in a solid matrix.
[0038]
First, a test was performed using a silane compound as a reducing agent. Specifically, SiO ₂ : Eu (15C5) ³⁺ , Me ₃ SiSiMe ₃ was produced. The creation procedure is as follows. A few drops of hydrochloric acid as a catalyst were added to a solution of Si (OC ₂ H ₅ ) ₄ : H ₂ O: C ₂ H ₅ OH = 1: 1: 5 (molar ratio), and the mixture was further refluxed for 1 hour. Then, to this solution _{EuC1 3: H 2 O: C} 2 H 5 OH: 15C5: Me 3 SiSiMe 3 = 0.03: 4: 4: 0.03: 0.06 to (mol ratio) was added, further 50 ° C. For 1 week at 90 ° C. for 2 days to obtain SiO ₂ : Eu (15C5) ³⁺ , Me ₃ SiSiMe ₃ . Table 1 shows the charge composition of a typical glass material.
[0039]
[Table 1]

[0040]
A sample without Me ₃ SiSiMe ₃ or crown ether was prepared in the same manner.
[0041]
Further, SiO ₂ : Eu (15C5) ³⁺ , Me ₃ SnSnMe ₃ was obtained by the same method.
[0042]
The hole burning characteristics were measured by forming holes using a rhodamine 6G dye laser. The temperature cycle experiment was conducted by forming holes at 77K, sequentially increasing the temperature to 100, 150, 200, 250 and 300K, holding the temperature for about 1 minute, returning to 77K, and measuring the excitation spectrum. Was.
[0043]
FIGS. 4 (a) and 4 (b) show the excitation spectra of SiO ₂ : Eu (15C5) ³⁺ , Me ₃ SiSiMe ₃ and SiO ₂ : Eu ³⁺ , Me ₃ SiSiMe ₃ before and after laser irradiation at 77 K and their difference spectra.
[0044]
The sample before irradiation, ⁷ F ₀ of ^{Eu 3+} ions in the wavelength region of 579-581Nm - excitation spectrum corresponding to the transition ⁵ D ₀ was observed. When these spectra were irradiated with a rhodamine 6G dye laser at 100 mW / mm ² for 600 seconds, holes having a half width of 0.125 nm were observed as shown in the figure.
[0045]
Regarding those without crown ether, even when the laser was irradiated, the emission intensity of the entire spectrum simply decreased, and no holes were formed. From this, it is apparent that Eu ³⁺ ions complexed with crown ether in the matrix are more likely to receive electrons from Me ₃ SiSiMe ₃ in an excited state than single Eu ³⁺ ions, so that holes can be efficiently formed. became.
[0046]
The spectrum was also observed for SiO ₂ : Eu (15C5) ³⁺ , Me ₃ SnSnMe ₃ . FIG. 5 shows an excitation spectrum of SiO ₂ : Eu (15C5) ³⁺ , Me ₃ SnSnMe ₃ before and after laser irradiation at 77 K, and a difference spectrum thereof.
[0047]
As a result, formation of holes was confirmed for Me ₃ SnSnMe ₃ containing crown ether (half-width: 0.141 nm). No holes were formed for those without crown ether. Therefore, it was revealed that in the matrix, the Eu ³⁺ ion complexed with the crown ether was easier to receive electrons from Me ₃ SnSnMe ₃ in the excited state than the single Eu ³⁺ ion, and it was found that holes could be formed more efficiently. .
[0048]
Example 4
Next, the temperature cycle characteristics of the photochemical hole burning medium of one embodiment of the present invention were examined.
[0049]
^{_{First, SiO 2: Eu (15C5)}} 3 + Me 3 SiSiMe 3, SiO 2: Eu (15C5) 3 + Me 3 SnSnMe 3, and _SiO 2: you create a Eu ^{(15C5) 3 +.} SiO _2: For _{^{Eu (15C5) 3 + Me 3}} SnSnMe 3, except using _{Me 3} SnSnMe 3 instead of Me ₃ SiSiMe 3, ^{_{also, SiO 2: Eu (15C5)}} 3 + For an electron-donating organic compound Was prepared using the same method as that of Example 3 except that it was not used.
[0050]
The temperature cycling characteristics were examined for these. That is, the temperature cycle characteristics at 77-300 K of the hole formed at 77 K in SiO ₂ : Eu (15C 5) ³⁺ , Me ₃ SiSiMe ₃ and SiO ₂ : Eu (15C 5) ³⁺ .Me ₃ SnSnMe ₃ were examined. FIG. 6 shows the results. FIG. 6A is a diagram showing a temperature cycle characteristic of SiO ₂ : Eu (15C5) ^{3 +} Me ₃ SiSiMe ₃ . FIG. 6B is a diagram showing a temperature cycle characteristic of SiO ₂ : Eu (15C5) ^{3 +} Me ₃ SnSnMe ₃ . FIG. 6C is a diagram showing a temperature cycle characteristic of SiO ₂ : Eu (15C5) ^{3 +} .
[0051]
For SiO ₂ : Eu (15C5) ^{3 +} Me ₃ SiSiMe ₃ , holes were held up to 300K. SiO _2: For _{^{Eu (15C5) 3 + Me 3}} SnSnMe 3, hole until the 250K is held.
[0052]
Although the uniform width increases and the depth of the hole decreases as the temperature rises, when Me ₃ SiSiMe ₃ is included at 300K, a hole having a half width of 0.479 nm and about 70% of the 77K depth is retained. Was done. Half width and approximately 61% of the hole depth of its 77K of _Me 3 In SnSnMe ₃ 0.474nm of 250K is held. Therefore, it can be seen that the medium to which the reducing agent is added has improved temperature stability of holes as compared with the medium containing only the crown ether complex. This is considered to be because introduction of Me ₃ MMMe ₃ (M = Si or Sn), which functions as a reducing agent, resulted in cleavage of the MM bond with reduction, thereby making it difficult for a reverse reaction to occur.
[0053]
Example 5
Next, the temperature cycle characteristics were examined by changing the concentration of the reducing agent. The preparation of the sample followed the method described in Example 3. Me ₃ SiSiMe ₃ was used as a reducing agent.
[0054]
FIG. 7 shows the results of the temperature cycle characteristics. FIG. 7 shows the temperature cycle characteristics of SiO ₂ : Eu (15C5) ^{3 +} Me ₃ SiSiMe ₃ . 7A shows a case where ₃ mol% of Me ₃ SiSiMe ₃ is used, and FIG. 7B shows a case where 6 mol% of Me ₃ SiSiMe ₃ is used.
[0055]
As is clear from FIG. 7, it is found that the stability of holes is higher when 6 mol% of Me ₃ SiSiMe ₃ is used than when 3 mol% is used. It is considered that this is because the amount of Eu (15C5) ^{3 +} to be reduced increased due to the increase in Me ₃ SiSiMe ₃ , and the holes became less likely to return.
[0056]
Example 6
Next, the spectrum when the solid matrix was changed was examined. As solid matrix, the _{SiO 2, Al 2 O 3,} TiO 2, ZrO 2, or was used to introduce the _Ta 2 _{O 5.} A sample was prepared in the same manner by the method described in Example 1.
[0057]
These samples were irradiated with laser and the excitation spectrum was observed. FIG. 8 shows excitation spectra before and after laser irradiation at 77 K of SiO ₂ -MxOy (Si: M = 7: 3): [Eu (15C5)] ³⁺ (Eu ³⁺ : 15C5 = 1: 3).
[0058]
In each case, the depth of the generated holes was not significantly different from that of SiO ₂ alone.
[0059]
Regarding the hole width, when Al ₂ O ₃ is introduced into SiO ₂ , Al ³⁺ combines with non-bridging oxygen to form a network as [AlO ₄ ]. Thereby, the local structure near the Eu ³⁺ ions is strengthened, and the hole width is reduced. It is considered that the same effect is obtained when ZrO ₂ and Ta ₂ O ₅ are introduced.
[0060]
In contrast, in the case of introducing TiO ₂ to SiO _2, it showed a tendency to hole width increases than SiO _2. This is because [TiO ₄ ] is considered to bind to bridging oxygen more than non-bridging oxygen.
[0061]
Next, these temperature cycle characteristics were examined. FIG. 9 and FIG. 10 show the temperature cycle characteristics of holes generated at 77 K of SiO ₂ -M _x O _y : [Eu (15C5)] ³⁺ .
In each case, holes were confirmed even after the temperature cycle to room temperature. In particular, when ZrO ₂ and Ta ₂ O ₅ were introduced, deeper holes remained at room temperature than when Al ₂ O ₃ was introduced.
[0062]
All of the solid matrices exhibited high hole stability at high temperatures. This is considered to be because the local structure in the vicinity of the Eu ³⁺ ions was strengthened, and the lattice vibration caused by adding a heavy element was suppressed.
[0063]
Example 7
A photochemical hole burning medium was prepared in the same manner as in Example 1, and the hole burning characteristics were evaluated in the same manner as in Example 3, except that indene was used as a reducing agent.
FIG. 11 shows an excitation spectrum before and after laser irradiation of SiO ₂ : Eu (15C5) ³⁺ and indene at 77 K, and a difference spectrum thereof.
As a result, formation of holes was confirmed. From these results, it can be seen that if the oxidation-reduction potential of indene is equal to or lower than that of indene, it functions well as a reducing agent and forms stable holes. Here, the redox potentials of the organic molecules are summarized in Table 2 below.
[Table 2]

It can be seen that all of the reducing agents listed in Table 2 give good photochemical hole burning characteristics because they are lower than the oxidation-reduction potential of indene.
[0064]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the hole burning medium of this invention, there exists an advantageous effect that a signal can be written according to the wavelength of the laser beam to irradiate.
[0065]
Further, according to the hole burning medium of the present invention, there is an advantageous effect that a wavelength division multiplexing type optical memory operable at room temperature can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram showing excitation spectra of SiO ₂ —ZrO ₂ : [Eu (15C5)] ³⁺ before and after laser beam irradiation.
FIG. 2 is a diagram showing a temperature cycle characteristic of SiO ₂ —ZrO ₂ : [Eu (15C5)] ³⁺ . FIG. 2A shows the case where SiO ₂ -ZrO ₂ = 7: 3, FIG. 2B shows the case where SiO ₂ -ZrO ₂ = 5: 5, and FIG. 2C shows the case where SiO ₂ -ZrO ₂ = 3: 7 is shown.
FIG. 3 is a diagram showing a fluorescence spectrum of SiO ₂ : [Eu (15C5)] ³⁺ before and after laser beam irradiation.
FIG. 4 shows spectra of a photochemical hole burning medium according to an embodiment of the present invention before and after laser irradiation.
FIG. 5 shows spectra of a photochemical hole burning medium according to an embodiment of the present invention before and after laser irradiation.
FIG. 6 shows temperature cycle characteristics of the photochemical hole burning medium according to one embodiment of the present invention. (A) _is, SiO ^2: is a diagram showing a temperature cycle characteristics of _{^{Eu (15C5) 3 + Me 3}} SiSiMe 3. (B) it _is, SiO ^2: is a diagram showing a temperature cycle characteristics of _{^{Eu (15C5) 3 + Me 3}} SnSnMe 3. (C) is a diagram showing a temperature cycle characteristic of SiO ₂ : Eu (15C5) ^{3 +} .
FIG. 7 shows a temperature cycle characteristic of SiO ₂ : Eu (15C5) ^{3 +} Me ₃ SiSiMe ₃ . (A) shows the case where ₃ mol% of Me ₃ SiSiMe ₃ is used, and (b) shows the case where 6 mol% of Me ₃ SiSiMe ₃ is used.
FIG. 8 shows excitation spectra before and after laser irradiation at 77 K of SiO ₂ -M _x O _y (Si: M = 7: 3): [Eu (15C5)] ³⁺ (Eu ³⁺ : 15C5 = 1: 3).
FIG. 9 shows temperature cycle characteristics of holes generated at 77 K of SiO ₂ -M _x O _y : [Eu (15C5)] ³⁺ .
FIG. 10 shows temperature cycle characteristics of holes generated at 77 K in SiO ₂ -M _x O _y : [Eu (15C5)] ³⁺ .
FIG. 11 shows an excitation spectrum before and after laser irradiation of SiO ₂ : Eu (15C5) ³⁺ and indene at 77 K, and a difference spectrum thereof.

Claims (10)

In a solid matrix, europium (III) crown ether complex, europium (III) polyether complex, at least one rare earth complex selected from the group consisting of europium (III) cryptand complex, and a material in which a reducing agent is dispersed. A photochemical hole burning medium characterized in that: Reducing agent, the medium according to claim 1, wherein a contributing reducing the stability of the hole. 3. The medium according to claim 2 , wherein the reducing agent is a silane compound or a disilazane compound. 4. The medium according to claim 3, wherein the silane compound or the disilazane compound is at least one selected from hexaalkyldisilane and hexaalkyldisilazane. 5. The medium according to claim 4, wherein the hexaalkyldisilane or hexaalkyldisilazane is hexamethyldisilane or hexamethyldisilazane. The medium according to claim 1, wherein the reducing agent is an organotin compound. 7. The medium according to claim 6, wherein the organotin compound is a compound represented by RSnSnR (where R represents an alkyl group or an aryl group). The medium according to any one of claims 1 to 7, wherein the solid matrix is at least one selected from the group consisting of silica, germanium oxide, boron oxide, phosphorus pentoxide, tellurium oxide, and a glass-forming compound. . 9. The medium according to claim 8, wherein the solid matrix further contains at least one selected from the group consisting of Al ₂ O ₃ , TiO ₂ , ZrO ₂ , and Ta ₂ O ₅ . The medium according to any one of claims 1 to 9, wherein the reducing agent has an oxidation-reduction potential of 1.5 V (vs. SCE) or less.

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