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Fabrication of gold nanoparticles and their influence on optical properties of dye-doped sol-gel films
Thin Solid Films 438 – 439 (2003) 39–43
Fabrication of gold nanoparticles and their influence on optical properties of dye-doped sol-gel films Masanori Fukushimaa,*, Hisao Yanagib, Shinji Hayashia,b, Naotoshi Suganumac, Yoshio Taniguchic a
Graduate School of Science and Technology, Kobe University, Rokkodai, Nada-ku, Kobe 657-8501, Japan b Faculty of Engineering, Kobe University, Rokkodai, Nada-ku, Kobe 657-8501, Japan c Faculty of Textile and Technology, Shinshu University, Tokida, Ueda, Nagano 386-8567, Japan
Abstract Au nanoparticles were generated in glass films by the sol–gel method. Au ions doped in silicaytitania films were reduced by UV light or electron-beam irradiations resulting in Au nanoparticles with a diameter smaller than 20 nm. This method enabled us to produce any patterns of Au nanoparticles in thin films. Using two-beam interference of a UV laser and electron-beam lithography, periodic structures of Au nanoparticles with submicrometer intervals were fabricated. Furthermore, doping of fluorescent dyes into the films containing Au nanoparticles exhibited selective reactivation or quenching of the photoluminescence. By generation of Au nanoparticles, the fluorescence of Rhodamine B was reactivated, whereas that of Coumarin 152 was quenched, depending on their electronic energy configurations with respect to the plasmon absorption band of the Au nanoparticles. This selective phenomenon also enabled us to make fluorescence patterning in the glass films. 䊚 2003 Elsevier Science B.V. All rights reserved. Keywords: Gold; Nanoparticle; Dye; Sol–gel method
1. Introduction Glasses doped with nanoparticles of metal and semiconductors have attracted much interest for potential applications as optoelectronic materials based on their nonlinear optical properties w1x as well as single-electron tunneling and charging phenomena w2x. Moreover, the nanoparticles that are the clusters of hundreds– thousands of metal and semiconductor atoms have the quantum effect resulting from their special electronic states, and development of devices using this effect is promising. On the other hand, organic molecules are alternative candidates for dopants into glass materials to give versatile photonic functions originating from their luminescent and photochemical properties w3x. To utilize these functionalized glasses for practical devices, a new simple method is necessary for embedding and arranging doped species in a desired structure in thin films. A sol–gel method w4x is one promising method for incorporating a variety of functional species in glass films *Corresponding author. Tel.yfax: q81-78-803-6185. E-mail address: [email protected] (M. Fukushima).
due to its low-temperature process involving hydrolysis and condensation reactions of metal alkoxides. In previous work, we doped fluorescent dye molecules in silica (SiO2)ytitania (TiO2 ) sol–gel films and observed thin-film lasing action under optical pumping w5x. We also prepared Au nanoparticles in SiO2 yTiO2 films using photochemical reduction of Au (III) ions doped in the precursor sol solution w6x. By means of this controllable photogeneration process, micropatterns of Au nanoparticles have been fabricated in the films using a photomask and other methods. In this study, we present fabrication of Au nanoparticles by electron-beam lithography and two-beam interference that enable us to generate more complicated and precise patterning in SiO2 yTiO2 films. Incorporation of inorganic nanoparticles with photoactive organic molecules would lead to new functionalized materials. From this point of view, we present here fabrication of hybrid SiO2 yTiO2 sol– gel films doped with Au nanoparticles and dye molecules and the influence of the nanoparticles on their fluorescence properties. 2. Experimental In our sol–gel process, spincoated films of SiO2 y
0040-6090/03/$ - see front matter 䊚 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0040-6090(03)00750-8
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M. Fukushima et al. / Thin Solid Films 438 – 439 (2003) 39–43
ions was performed by UV irradiation at ls365 nm using a high-pressure Hg lamp, electron-beam lithography and two-beam interference with a He–Cd laser (ls 325 nm). The Au nanoparticles were presumed to be formed according to the following reaction formula:
Fig. 1. Molecular structures of RB and C152.
TiO2 containing chloroauric acid (HAuCl4) and laser dyes were prepared on a glass substrate from an ethanol solution of tetraethyl orthosilicate (Si(OC2H5)4)ytetraethyl orthotitanate (Ti(OC2H5)4) mixtures under acid catalysis. Laser dyes used are Rhodamine B (RB) and Coumarin 152 (C152) as shown in Fig. 1. The dopant amount of the laser dye and HAuCl4 are 0.1 and 1.0 mol%, respectively. The reason for the choice of SiO2 and TiO2 is to make an optimal matrix structure for generation of Au particles. In the matrix films including only SiO2 or TiO2, it was difficult to produce welldispersed Au nanoparticles having a spherical shape. The volume ratio of SiO2:TiO2 in the matrix films was optimized to be 2:1 to produce homogeneously doped films with optical flatness as well as to make generation of nanoparticles possible as mentioned below. A higher ratio of SiO2 made the film surface rough, while a higher ratio of TiO2 resulted in opaque films owing to the fast hydrolysis reactivity of Ti(OC2H5)4. Thus, neatly coated films were transparent. Photogeneration of Au nanoparticles in the SiO2 yTiO2 film doped with Au
Fig. 2. Schematic diagram for optical system of two-beam interference.
Au nanoparticle patterning was carried out by UV irradiation through a comb-like mask on the Au (ion)– SiO2 yTiO2 film. The electron-beam lithography (Tokyo Technology DRAW 531DLB) was performed with a scanning electron microscope (JEOL S-3100H). The electron beam was irradiated by 100 pA and 20 kV for 6 h along a designed pattern controlled by a personal computer. An optical setup for the two-beam interference is schematically shown in Fig. 2. The direct beam and the reflected beam interfere on the sample surface, giving rise to one dimensional diffraction fringes. It is easy to tune the grating intervals by changing the angle of the mirror. The grating intervals L is expressed by the equation sin usly2L, where u is incident angle of the pumping beam and l is a wavelength of the pumping beam. Optical properties and structures of the prepared films were investigated by a transmission electron microscope (Hitachi H-7100TE), scanning near-field optical microscope (SNOM)yconfocal laser scanning microscope (CLSM, JEOL JSPM-4300), atomic force microscope (AFM, JEOL JSPM-4200) and fluorescence microscope (OLYMPUS IX70). 3. Results and discussion As shown in Fig. 3a, transmission electron microscopy of the UV-irradiated Au–SiO2 yTiO2 film confirms that spherical particles with an average diameter of 20 nm homogeneously dispersed in the film and its electron diffraction pattern in Fig. 3b indicates the (1 1 1) and (2 2 0) spacings of the Au crystals. After UV irradiation by a high-pressure Hg lamp for 20 min, the absorption spectrum of the film changed showing a shifted peak at lmaxs550 nm and a broad tail at 500–550 nm, which was assigned to the surface plasmon band of generated Au nanoparticles w7x. The difference in the visible absorption resulting from generation of Au nanoparticles is also discriminated in a transmission optical micrograph of photopatterned films as shown in Fig. 4a. The region UV-irradiated through a comb-like photomask exhibits a higher optical density due to the broad plasmon band of the Au nanoparticles. Furthermore, the
M. Fukushima et al. / Thin Solid Films 438 – 439 (2003) 39–43
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Fig. 5. Optical micrographs of Au nanoparticles in SiO2yTiO2 films patterned by electron-beam lithography (a) and (b). The inset in (b) indicates absorption spectrum obtained from the patterned area.
Fig. 3. Electron micrograph and electron diffraction pattern of Au nanoparticles generated in UV-irradiated Au–SiO2yTiO2 film.
use of SNOM showed details of the patterned Au nanoparticles in Fig. 4b. Individual Au nanoparticles can be discriminated on the edge of the patterned line due to the plasmon absorption by the Au nanoparticles in the vicinity of the near-field probe. Au nanoparticles were also generated by direct reduction with electronbeam irradiation using SEM. Any complicated image could be made in the SiO2 yTiO2 film by this electronbeam lithography method. Fig. 5a and b show microscale lines and dots composed of Au nanoparticles generated in the SiO2 yTiO2 film. In these patterns, the electron beam was scanned along the line area between 5-mm width and the dots between 10-mm diameter. Advantages
Fig. 4. Transmission optical micrograph (a) and near-field optical microscopic image (b) of Au–SiO2yTiO2 film after UV irradiation through a comb-like photomask.
of this method are easy fabrication of two dimensional, complicated patterns under control with a personal computer. Absorption spectra taken from these patterns exhibited a plasmon band approximately 500 nm as shown in Fig. 5b, suggesting that Au nanoparticles were generated by the electron-beam reduction. Furthermore, for making precise, periodic structures of Au nanoparticles, we used the two-beam interference of He–Cd laser beams. This method makes possible to establish submicroscale gratings in the SiO2 yTiO2 films by generation of Au nanoparticles. Fig. 6 shows the grating images composed of generated Au nanoparticles observed by CLSM (ls532 nm). These images exhibited a change of grating intervals from 423 nm (a) to 600 nm (b). Fig. 7 shows an AFM image of the surface of this grating sample. This image indicates that the surface corrugation is less than a few nanometers, exhibiting an optical flatness. The change of fluorescence images of dye-doped films by generation of Au nanoparticles is investigated by fluorescence microscope as shown in Fig. 8. A SiO2 yTiO2 film doped with RB was excited at ls546 nm, while a film doped with C152 was excited at ls 365 nm. In the film doped with RB and Au nanoparticles
Fig. 6. CLSM images of Au–SiO2 yTiO2 films photopatterned by twobeam interference with different grating intervals at the mirror angles of 73.138 (a) and 67.418 (b).
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M. Fukushima et al. / Thin Solid Films 438 – 439 (2003) 39–43
Fig. 7. AFM image of the surface of Au–SiO2yTiO2 film was patterned by two-beam interference irradiation.
(AuyRB–SiO2 yTiO2), the UV-irradiated region shows a red emission corresponding to the fluorescence of the doped RB, while the region covered by a comb-like mask with a 3-mm gap exhibits no light emission. An RB-doped SiO2 yTiO2 (RB–SiO2 yTiO2 ) film including no Au (III) ions was very emissive w5x, whereas the present as-coated Au (ion)yRB–SiO2 yTiO2 film before UV irradiation was not fluorescent. The intensity of fluorescence appearing in the Au (nanoparticle)yRB– SiO2 yTiO2 film increased with the irradiation time, but then saturated when all Au (III) ions were reduced to Au nanoparticles. This transient appearance of fluorescence was observed by a fluorescence microscope as shown in Fig. 9, and its photochemical process obeying the first-order rate law w6x. On the other hand, in the AuyC152–SiO2 yTiO2 film, the UV-irradiated region exhibited no light emission, while the masked region showed blue emission, as reverse as the AuyRB–SiO2 y TiO2 film. The reason for these different fluorescence behaviors is schematically shown in Fig. 10. The excited
Fig. 8. Fluorescence micrographs of AuyRB–SiO2yTiO2 (a) and AuyC152–SiO2yTiO2 (b) films photopatterned by a comb-like mask.
Fig. 9. Changes in fluorescence micrographs of AuyRB–SiO2yTiO2 film with UV irradiation time.
state of RB is quenched by the residual Au ion due to the excited electron transfer in the masked region, while this quenching does not occur in the area where the Au nanoparticles are generated probably because the electron transfer to the neutralized Au particle is prohibited. On the other hand, the nonionic C152 molecule keeps its emission intact against the quenching because the interaction between the neutral C152 molecules and the Au ions are weak. After generation of Au nanoparticles, the excited state of C152 is energy-transferred to the Au nanoparticles since the transition energy for the fluores-
Fig. 10. Schematic diagram for photoemission and quenching mechanisms of Au (ion)ydye–SiO2yTiO2 and Au (nanoparticle)ydye– SiO2yTiO2 films.
M. Fukushima et al. / Thin Solid Films 438 – 439 (2003) 39–43
cence band of C152 is higher than the plasmon band energy of the Au nanoparticles. 4. Conclusions The present photoresponsive generation process enabled us to form optically modulated structures with Au nanoparticles in thin glass films. This method also provided us fluorescence patterning in dye-doped films. Such modification of thin glass films based on generation of nanoparticles would be useful for nanofabrication of new optical devices with inorganicyorganic composite materials.
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References w1x R.K. Jain, R.C. Lind, J. Opt. Soc. Am. 73 (1983) 647. w2x M. Amman, R. Wilkins, E. Ben-Jacob, P.D. Maker, R.C. Jaklevic, Phys. Rev. 43 (1991) 1146. w3x D. Avnir, D. Levy, R. Reisfeld, J. Phys. Chem. 88 (1984) 5956. w4x H. Dislich, Angew. Chem., Int. Ed. Engl. 6 (1996) 1879. w5x H. Yanagi, T. Hishiki, T. Tobitani, A. Otomo, S. Mashiko, Chem. Phys. Lett. 292 (1998) 332. w6x H. Yanagi, L.A. Nagahara, S. Mashiko, H. Yokumoto, Chem. Mater. 10 (1998) 1258. w7x W.P. Halperin, Rev. Mod. Phys. 58 (1986) 533, and references therein.
Fabrication of gold nanoparticles and their influence on optical properties of dye-doped sol-gel films Masanori Fukushimaa,*, Hisao Yanagib, Shinji Hayashia,b, Naotoshi Suganumac, Yoshio Taniguchic a
Graduate School of Science and Technology, Kobe University, Rokkodai, Nada-ku, Kobe 657-8501, Japan b Faculty of Engineering, Kobe University, Rokkodai, Nada-ku, Kobe 657-8501, Japan c Faculty of Textile and Technology, Shinshu University, Tokida, Ueda, Nagano 386-8567, Japan
Abstract Au nanoparticles were generated in glass films by the sol–gel method. Au ions doped in silicaytitania films were reduced by UV light or electron-beam irradiations resulting in Au nanoparticles with a diameter smaller than 20 nm. This method enabled us to produce any patterns of Au nanoparticles in thin films. Using two-beam interference of a UV laser and electron-beam lithography, periodic structures of Au nanoparticles with submicrometer intervals were fabricated. Furthermore, doping of fluorescent dyes into the films containing Au nanoparticles exhibited selective reactivation or quenching of the photoluminescence. By generation of Au nanoparticles, the fluorescence of Rhodamine B was reactivated, whereas that of Coumarin 152 was quenched, depending on their electronic energy configurations with respect to the plasmon absorption band of the Au nanoparticles. This selective phenomenon also enabled us to make fluorescence patterning in the glass films. 䊚 2003 Elsevier Science B.V. All rights reserved. Keywords: Gold; Nanoparticle; Dye; Sol–gel method
1. Introduction Glasses doped with nanoparticles of metal and semiconductors have attracted much interest for potential applications as optoelectronic materials based on their nonlinear optical properties w1x as well as single-electron tunneling and charging phenomena w2x. Moreover, the nanoparticles that are the clusters of hundreds– thousands of metal and semiconductor atoms have the quantum effect resulting from their special electronic states, and development of devices using this effect is promising. On the other hand, organic molecules are alternative candidates for dopants into glass materials to give versatile photonic functions originating from their luminescent and photochemical properties w3x. To utilize these functionalized glasses for practical devices, a new simple method is necessary for embedding and arranging doped species in a desired structure in thin films. A sol–gel method w4x is one promising method for incorporating a variety of functional species in glass films *Corresponding author. Tel.yfax: q81-78-803-6185. E-mail address: [email protected] (M. Fukushima).
due to its low-temperature process involving hydrolysis and condensation reactions of metal alkoxides. In previous work, we doped fluorescent dye molecules in silica (SiO2)ytitania (TiO2 ) sol–gel films and observed thin-film lasing action under optical pumping w5x. We also prepared Au nanoparticles in SiO2 yTiO2 films using photochemical reduction of Au (III) ions doped in the precursor sol solution w6x. By means of this controllable photogeneration process, micropatterns of Au nanoparticles have been fabricated in the films using a photomask and other methods. In this study, we present fabrication of Au nanoparticles by electron-beam lithography and two-beam interference that enable us to generate more complicated and precise patterning in SiO2 yTiO2 films. Incorporation of inorganic nanoparticles with photoactive organic molecules would lead to new functionalized materials. From this point of view, we present here fabrication of hybrid SiO2 yTiO2 sol– gel films doped with Au nanoparticles and dye molecules and the influence of the nanoparticles on their fluorescence properties. 2. Experimental In our sol–gel process, spincoated films of SiO2 y
0040-6090/03/$ - see front matter 䊚 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0040-6090(03)00750-8
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M. Fukushima et al. / Thin Solid Films 438 – 439 (2003) 39–43
ions was performed by UV irradiation at ls365 nm using a high-pressure Hg lamp, electron-beam lithography and two-beam interference with a He–Cd laser (ls 325 nm). The Au nanoparticles were presumed to be formed according to the following reaction formula:
Fig. 1. Molecular structures of RB and C152.
TiO2 containing chloroauric acid (HAuCl4) and laser dyes were prepared on a glass substrate from an ethanol solution of tetraethyl orthosilicate (Si(OC2H5)4)ytetraethyl orthotitanate (Ti(OC2H5)4) mixtures under acid catalysis. Laser dyes used are Rhodamine B (RB) and Coumarin 152 (C152) as shown in Fig. 1. The dopant amount of the laser dye and HAuCl4 are 0.1 and 1.0 mol%, respectively. The reason for the choice of SiO2 and TiO2 is to make an optimal matrix structure for generation of Au particles. In the matrix films including only SiO2 or TiO2, it was difficult to produce welldispersed Au nanoparticles having a spherical shape. The volume ratio of SiO2:TiO2 in the matrix films was optimized to be 2:1 to produce homogeneously doped films with optical flatness as well as to make generation of nanoparticles possible as mentioned below. A higher ratio of SiO2 made the film surface rough, while a higher ratio of TiO2 resulted in opaque films owing to the fast hydrolysis reactivity of Ti(OC2H5)4. Thus, neatly coated films were transparent. Photogeneration of Au nanoparticles in the SiO2 yTiO2 film doped with Au
Fig. 2. Schematic diagram for optical system of two-beam interference.
Au nanoparticle patterning was carried out by UV irradiation through a comb-like mask on the Au (ion)– SiO2 yTiO2 film. The electron-beam lithography (Tokyo Technology DRAW 531DLB) was performed with a scanning electron microscope (JEOL S-3100H). The electron beam was irradiated by 100 pA and 20 kV for 6 h along a designed pattern controlled by a personal computer. An optical setup for the two-beam interference is schematically shown in Fig. 2. The direct beam and the reflected beam interfere on the sample surface, giving rise to one dimensional diffraction fringes. It is easy to tune the grating intervals by changing the angle of the mirror. The grating intervals L is expressed by the equation sin usly2L, where u is incident angle of the pumping beam and l is a wavelength of the pumping beam. Optical properties and structures of the prepared films were investigated by a transmission electron microscope (Hitachi H-7100TE), scanning near-field optical microscope (SNOM)yconfocal laser scanning microscope (CLSM, JEOL JSPM-4300), atomic force microscope (AFM, JEOL JSPM-4200) and fluorescence microscope (OLYMPUS IX70). 3. Results and discussion As shown in Fig. 3a, transmission electron microscopy of the UV-irradiated Au–SiO2 yTiO2 film confirms that spherical particles with an average diameter of 20 nm homogeneously dispersed in the film and its electron diffraction pattern in Fig. 3b indicates the (1 1 1) and (2 2 0) spacings of the Au crystals. After UV irradiation by a high-pressure Hg lamp for 20 min, the absorption spectrum of the film changed showing a shifted peak at lmaxs550 nm and a broad tail at 500–550 nm, which was assigned to the surface plasmon band of generated Au nanoparticles w7x. The difference in the visible absorption resulting from generation of Au nanoparticles is also discriminated in a transmission optical micrograph of photopatterned films as shown in Fig. 4a. The region UV-irradiated through a comb-like photomask exhibits a higher optical density due to the broad plasmon band of the Au nanoparticles. Furthermore, the
M. Fukushima et al. / Thin Solid Films 438 – 439 (2003) 39–43
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Fig. 5. Optical micrographs of Au nanoparticles in SiO2yTiO2 films patterned by electron-beam lithography (a) and (b). The inset in (b) indicates absorption spectrum obtained from the patterned area.
Fig. 3. Electron micrograph and electron diffraction pattern of Au nanoparticles generated in UV-irradiated Au–SiO2yTiO2 film.
use of SNOM showed details of the patterned Au nanoparticles in Fig. 4b. Individual Au nanoparticles can be discriminated on the edge of the patterned line due to the plasmon absorption by the Au nanoparticles in the vicinity of the near-field probe. Au nanoparticles were also generated by direct reduction with electronbeam irradiation using SEM. Any complicated image could be made in the SiO2 yTiO2 film by this electronbeam lithography method. Fig. 5a and b show microscale lines and dots composed of Au nanoparticles generated in the SiO2 yTiO2 film. In these patterns, the electron beam was scanned along the line area between 5-mm width and the dots between 10-mm diameter. Advantages
Fig. 4. Transmission optical micrograph (a) and near-field optical microscopic image (b) of Au–SiO2yTiO2 film after UV irradiation through a comb-like photomask.
of this method are easy fabrication of two dimensional, complicated patterns under control with a personal computer. Absorption spectra taken from these patterns exhibited a plasmon band approximately 500 nm as shown in Fig. 5b, suggesting that Au nanoparticles were generated by the electron-beam reduction. Furthermore, for making precise, periodic structures of Au nanoparticles, we used the two-beam interference of He–Cd laser beams. This method makes possible to establish submicroscale gratings in the SiO2 yTiO2 films by generation of Au nanoparticles. Fig. 6 shows the grating images composed of generated Au nanoparticles observed by CLSM (ls532 nm). These images exhibited a change of grating intervals from 423 nm (a) to 600 nm (b). Fig. 7 shows an AFM image of the surface of this grating sample. This image indicates that the surface corrugation is less than a few nanometers, exhibiting an optical flatness. The change of fluorescence images of dye-doped films by generation of Au nanoparticles is investigated by fluorescence microscope as shown in Fig. 8. A SiO2 yTiO2 film doped with RB was excited at ls546 nm, while a film doped with C152 was excited at ls 365 nm. In the film doped with RB and Au nanoparticles
Fig. 6. CLSM images of Au–SiO2 yTiO2 films photopatterned by twobeam interference with different grating intervals at the mirror angles of 73.138 (a) and 67.418 (b).
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M. Fukushima et al. / Thin Solid Films 438 – 439 (2003) 39–43
Fig. 7. AFM image of the surface of Au–SiO2yTiO2 film was patterned by two-beam interference irradiation.
(AuyRB–SiO2 yTiO2), the UV-irradiated region shows a red emission corresponding to the fluorescence of the doped RB, while the region covered by a comb-like mask with a 3-mm gap exhibits no light emission. An RB-doped SiO2 yTiO2 (RB–SiO2 yTiO2 ) film including no Au (III) ions was very emissive w5x, whereas the present as-coated Au (ion)yRB–SiO2 yTiO2 film before UV irradiation was not fluorescent. The intensity of fluorescence appearing in the Au (nanoparticle)yRB– SiO2 yTiO2 film increased with the irradiation time, but then saturated when all Au (III) ions were reduced to Au nanoparticles. This transient appearance of fluorescence was observed by a fluorescence microscope as shown in Fig. 9, and its photochemical process obeying the first-order rate law w6x. On the other hand, in the AuyC152–SiO2 yTiO2 film, the UV-irradiated region exhibited no light emission, while the masked region showed blue emission, as reverse as the AuyRB–SiO2 y TiO2 film. The reason for these different fluorescence behaviors is schematically shown in Fig. 10. The excited
Fig. 8. Fluorescence micrographs of AuyRB–SiO2yTiO2 (a) and AuyC152–SiO2yTiO2 (b) films photopatterned by a comb-like mask.
Fig. 9. Changes in fluorescence micrographs of AuyRB–SiO2yTiO2 film with UV irradiation time.
state of RB is quenched by the residual Au ion due to the excited electron transfer in the masked region, while this quenching does not occur in the area where the Au nanoparticles are generated probably because the electron transfer to the neutralized Au particle is prohibited. On the other hand, the nonionic C152 molecule keeps its emission intact against the quenching because the interaction between the neutral C152 molecules and the Au ions are weak. After generation of Au nanoparticles, the excited state of C152 is energy-transferred to the Au nanoparticles since the transition energy for the fluores-
Fig. 10. Schematic diagram for photoemission and quenching mechanisms of Au (ion)ydye–SiO2yTiO2 and Au (nanoparticle)ydye– SiO2yTiO2 films.
M. Fukushima et al. / Thin Solid Films 438 – 439 (2003) 39–43
cence band of C152 is higher than the plasmon band energy of the Au nanoparticles. 4. Conclusions The present photoresponsive generation process enabled us to form optically modulated structures with Au nanoparticles in thin glass films. This method also provided us fluorescence patterning in dye-doped films. Such modification of thin glass films based on generation of nanoparticles would be useful for nanofabrication of new optical devices with inorganicyorganic composite materials.
43
References w1x R.K. Jain, R.C. Lind, J. Opt. Soc. Am. 73 (1983) 647. w2x M. Amman, R. Wilkins, E. Ben-Jacob, P.D. Maker, R.C. Jaklevic, Phys. Rev. 43 (1991) 1146. w3x D. Avnir, D. Levy, R. Reisfeld, J. Phys. Chem. 88 (1984) 5956. w4x H. Dislich, Angew. Chem., Int. Ed. Engl. 6 (1996) 1879. w5x H. Yanagi, T. Hishiki, T. Tobitani, A. Otomo, S. Mashiko, Chem. Phys. Lett. 292 (1998) 332. w6x H. Yanagi, L.A. Nagahara, S. Mashiko, H. Yokumoto, Chem. Mater. 10 (1998) 1258. w7x W.P. Halperin, Rev. Mod. Phys. 58 (1986) 533, and references therein.