Silver ions are embedded in glass slides by a traditional "wet" ion exchange technique. The glass slides irradiation by 10 ns laser pulses at 355 nm wavelength leads to the formation of metal-like film at the surface. Scanning electron microscopy shows that the films presents a dense layer of silver nanoparticles about the same size and separation. Varying the irradiation parameters results in a significant difference in the transmission spectra of the slides. Particle size grows when the laser power increases.<br/

Abdolvand, A.

Lipovskii, A.

Reduto, I.

Svirko, Yu

Wackerow, S.

Zolotovskaya, S

English

Discovery Research Portal

                                                                    University of DundeeNanosecond Laser Surface Silver Metallization of Wet Ion Exchanged GlassesReduto, I.; Wackerow, S.; Zolotovskaya, S; Abdolvand, A.; Lipovskii, A.; Svirko, YuPublished in:Journal of Physics: Conference SeriesDOI:10.1088/1742-6596/1461/1/012136Publication date:2020Licence:CC BYDocument VersionPublisher's PDF, also known as Version of recordLink to publication in Discovery Research PortalCitation for published version (APA):Reduto, I., Wackerow, S., Zolotovskaya, S., Abdolvand, A., Lipovskii, A., & Svirko, Y. (2020). Nanosecond LaserSurface Silver Metallization of Wet Ion Exchanged Glasses. In Journal of Physics: Conference Series:METANANO 2019 15-19 July 2019, St. Petersburg, Russian Federation (Vol. 1461, pp. 1-5). Article 012136(Journal of Physics: Conference Series). IOP Publishing Ltd.. https://doi.org/10.1088/1742-6596/1461/1/012136General rightsCopyright and moral rights for the publications made accessible in Discovery Research Portal are retained by the authors and/or othercopyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated withthese rights.Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Download date: 24. Sep. 2025Journal of Physics: Conference SeriesPAPER • OPEN ACCESSNanosecond Laser Surface Silver Metallization of Wet Ion ExchangedGlassesTo cite this article: I Reduto et al 2020 J. Phys.: Conf. Ser. 1461 012136 View the article online for updates and enhancements.This content was downloaded from IP address 2.121.108.145 on 07/05/2020 at 11:44Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing LtdMETANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121361      Nanosecond Laser Surface Silver Metallization of Wet Ion Exchanged Glasses I Reduto1,2,3, S Wackerow4, S Zolotovskaya4, A Abdolvand4, A Lipovskii2,3, Yu Svirko1 1Institute of Photonics, Department of Physics and Mathematics, University of Eastern Finland, Joensuu 80101, Finland  2Institute of Physics, Nanotechnology and Telecommunication, Peter the Great St. Petersburg Polytechnic University, St. Petersburg 195251, Russia  3Department of Physics and Technology of Nanostructures, St. Petersburg Academic University, Saint Petersburg 194021, Russia 4School of Engineering, Physics & Mathematics, University of Dundee, Dundee DD1 4HN, UK reduto-igor@mail.ru Abstract. Silver ions are embedded in glass slides by a traditional “wet” ion exchange technique. The glass slides irradiation by 10 ns laser pulses at 355 nm wavelength leads to the formation of metal-like film at the surface. Scanning electron microscopy shows that the films presents a dense layer of silver nanoparticles about the same size and separation. Varying the irradiation parameters results in a significant difference in the transmission spectra of the slides. Particle size grows when the laser power increases. Introduction Noble metal nanoparticles are interesting due to their unique nonlinear optical properties [1–3]. The optical properties of a glass embedded with silver nanoparticles can be controlled via varying physical properties of nanoparticles, and this makes the glass-metal nanocomposites promising candidates for numerous applications in optoelectronics [4] and sensing [5]. The optical properties of these glassy composites are dominated by the SPRs which are specific for different metals and different types of surrounding matrix, size, shape, spatial distribution and concentration of the metal inclusions. The manipulation of physical properties of nanoparticles changes their surface plasmon resonance (SPR) position and, respectively, optical properties of the composites. Controllable two-step fabrication of silver-glass composite by dry field-assisted ion-exchange with subsequent laser irradiation has been reported [6]. The main aim of this work is the study of the composite formation as the result of the interaction between ns-pulsed laser and silver ions embedded to the glass slide using “wet” silver-sodium ion-exchange. In this paper, we present the optical and structural properties of the nanocomposite. Experimental methods To embed silver ions into glass matrix, soda-lime glass slides were ion-exchanged in silver-sodium melt solution: 5%wt.AgNO3: 95%wt.NaNO3 for 20 min at 325°C. In the process sodium ions were replaced by silver ions in several microns deep subsurface layer of the glass. Prepared samples were irradiated by METANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121362      3rd harmonic of pulsed Nd:YVO4 laser (pulse length τ = 10 ns) at λ = 355 nm wavelength (edge of absorption of the glass) in standard atmospheric environment (room temperature and normal pressure). The laser beam had a Gaussian intensity profile and was focused onto the sample surface using a flat-field scanning lens system. The diameter of the focused spot (φ) was about 60 µm. Samples were irradiated with laser pulse repetition frequency of 80 kHz,  by scanning line-by-line with the speed of 1 mm/s (4800 pulse/spot). Laser output energy density (laser fluence) was varied from 332 to 197 mJ/cm2. The irradiated areas were characterized using Specord 50 spectrophotometer, Leica digital microscope, and a LEO 1550 Gemini scanning electron microscope (SEM). The list of prepared samples is presented in Table 1.  Table 1. The list of parameters of prepared samples Sample name #1 #2 #3 #4 Energy per pulse, μJ 9.38 9.00 6.94 5.56 Laser fluence, mJ/cm2 332 319 246 197 Results and discussions Photographs of the prepared samples are presented in Figs. 1,2. As seen, only particles on the glass surface were formed by laser pulses with the energy below ~6 μJ. Starting from 7 μJ energy of the irradiating pulses, bulk nanoparticles formation in the glass volume occurred Increasing pulse energy resulted in stronger reflection. At 9 μJ pulse energy the films started to become rough because of overheat resulted in bubbles and cracks formation near the glass surface.    Figure 1. Photos of the laser modified areas of the sample. From left to right areas #1 - #4. The sizes of the squares are 2.4x2.4 mm2. Images (a) and (b) were taken with different illumination.            Figure 2. Optical microscopy images of the samples taken with 5x magnification. Images (a-d) and (e-h) correspond to the samples #1 - #4. Images (a-d) were obtained in reflection mode and images (e-h) correspond to the transmission mode. The lines result from the scanning of the laser beam.  Optical absorption spectra of the irradiated areas are shown in Fig. 3. Optical density increases for higher irradiation laser power, which is also in accordance with Figs. 1,2. It is important to note that the peak of the absorption spectra lies at 440 nm wavelength, which is typical for spherical silver nanoparticles. Increase of the absorption means bigger amount of nanoparticles, while broadening of the absorption peak indicates broadening of the nanoparticles size distribution or an increase in their volume fraction. (a) (b) (c) (d) (e) (f) (g) (h) (a) (b) METANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121363      400 600 800 10000,00,51,01,52,02,5Absorption, a.u.Wavelength, nmfree Ion exchanged5.56 μJ6.94 μJ9.00 μJ9.38 μJIrradiation Figure 3. Optical absorption spectra. Figures near corresponding spectra indicate laser pulse energy.  SEM images taken in the centre of the irradiated lines show that under decreasing the laser power the average silver nanoparticle size drops from 15 to 10 nm. This is well correlated with optical spectroscopy data presented in Fig. 3.      Figure 4. SEM images of the samples taken in the center of the irradiated lines. Images (a-d) correspond to the samples #1 - #4.  The laser beam focused on the glass surface with the spot size of 60 µm creates ~60 µm wide line of nanoparticles when scanned. Silver nanoparticles up to 500 nm in size were grown at the border of this line. In Fig. 5 one can see the presence of nanoparticles outside the irradiated line. This line broadening is caused by laser heating of the glass surface, which results in the formation of silver nanoparticles in the glass bulk (about 60 µm  deep region – see Fig. 6) and on the glass surface near the irradiated area. The broadening of the line is about 30 µm from each side of the line. The size of silver nanoparticles outside the line is about 1.5-2 times bigger, and the nanoparticles are denser then inside of the irradiated area. This effect should be taken in account for line-by-line metallisation of a glass.   (a) (b) (c) (d) METANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121364         Figure 5. SEM of individual 60 µm-wide line drown by the laser on the sample #4 surface (a). Images taken inside the line (b), at the border of the line (c) and outside (d) the line.       Figure 6. SEM of the chipped glass (side view). One can see 60 microns thick region enriched with the nanoparticles. Conclusion The formation of silver nanoparticles in the glass embedded silver ions via classic wet ion-exchange under nanosecond (10 ns) pulsed Nd:YVO4 laser irradiation at 355 nm wavelength is demonstrated. Increase of the laser power resulted in the growth of the average nanoparticle size. This technique of controlled local formation of the nanoparticles by pulsed laser irradiation allows one to create complex patterns of closely-positioned nanoparticles in glasses containing silver ions. Acknowledgments I.R. thanks the support of his research visit to the University of Dundee for the experiments on laser modification of the samples by the University of Eastern Finland and Academy of Finland (grant #323052); preparation of the ion-exchanged glass samples and their characterization after the laser processing were supported by Russian Scientific Foundation (project #16-12-10044). References [1] Aslan K, McDonald K, Previte M J R, Zhang Y and Geddes C D 2008 Chem. Phys. Lett. 464 216–219 [2] Stenzel O and Macleod A 2012 Adv. Opt. Technol. 1 (6) 463–481 [3] De Julián Fernández C, et al. 2005 Sensors Actuators, B Chem. 111–112 225–229 [4] Inácio P L, Barreto B J, Horowitz F, Correia R R B and Pereira M B 2013 Opt. Mater. Express 3 (3) 390 [5] Xie X S and Dunn R C 1994 Science 265 361–364 [6] Wackerow S and Abdolvand A 2014 Opt. Express 22 (5) 5076  Surface (b) (c) (d) 60 µm  Cut (a) 

Nanosecond Laser Surface Silver Metallization of Wet Ion Exchanged Glasses

                                                                    University of DundeeNanosecond Laser Surface Silver Metallization of Wet Ion Exchanged GlassesReduto, I.; Wackerow, S.; Zolotovskaya, S; Abdolvand, A.; Lipovskii, A.; Svirko, YuPublished in:Journal of Physics: Conference SeriesDOI:10.1088/1742-6596/1461/1/012136Publication date:2020Document VersionPublisher's PDF, also known as Version of recordLink to publication in Discovery Research PortalCitation for published version (APA):Reduto, I., Wackerow, S., Zolotovskaya, S., Abdolvand, A., Lipovskii, A., & Svirko, Y. (2020). Nanosecond LaserSurface Silver Metallization of Wet Ion Exchanged Glasses. In Journal of Physics: Conference Series:METANANO 2019 15-19 July 2019, St. Petersburg, Russian Federation (Vol. 1461, pp. 1-5). [012136] (Journalof Physics: Conference Series). IOP Publishing Ltd.. https://doi.org/10.1088/1742-6596/1461/1/012136General rightsCopyright and moral rights for the publications made accessible in Discovery Research Portal are retained by the authors and/or othercopyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated withthese rights. • Users may download and print one copy of any publication from Discovery Research Portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain. • You may freely distribute the URL identifying the publication in the public portal.Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Download date: 11. May. 2020Journal of Physics: Conference SeriesPAPER • OPEN ACCESSNanosecond Laser Surface Silver Metallization of Wet Ion ExchangedGlassesTo cite this article: I Reduto et al 2020 J. Phys.: Conf. Ser. 1461 012136 View the article online for updates and enhancements.This content was downloaded from IP address 2.121.108.145 on 07/05/2020 at 11:44Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing LtdMETANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121361      Nanosecond Laser Surface Silver Metallization of Wet Ion Exchanged Glasses I Reduto1,2,3, S Wackerow4, S Zolotovskaya4, A Abdolvand4, A Lipovskii2,3, Yu Svirko1 1Institute of Photonics, Department of Physics and Mathematics, University of Eastern Finland, Joensuu 80101, Finland  2Institute of Physics, Nanotechnology and Telecommunication, Peter the Great St. Petersburg Polytechnic University, St. Petersburg 195251, Russia  3Department of Physics and Technology of Nanostructures, St. Petersburg Academic University, Saint Petersburg 194021, Russia 4School of Engineering, Physics & Mathematics, University of Dundee, Dundee DD1 4HN, UK reduto-igor@mail.ru Abstract. Silver ions are embedded in glass slides by a traditional “wet” ion exchange technique. The glass slides irradiation by 10 ns laser pulses at 355 nm wavelength leads to the formation of metal-like film at the surface. Scanning electron microscopy shows that the films presents a dense layer of silver nanoparticles about the same size and separation. Varying the irradiation parameters results in a significant difference in the transmission spectra of the slides. Particle size grows when the laser power increases. Introduction Noble metal nanoparticles are interesting due to their unique nonlinear optical properties [1–3]. The optical properties of a glass embedded with silver nanoparticles can be controlled via varying physical properties of nanoparticles, and this makes the glass-metal nanocomposites promising candidates for numerous applications in optoelectronics [4] and sensing [5]. The optical properties of these glassy composites are dominated by the SPRs which are specific for different metals and different types of surrounding matrix, size, shape, spatial distribution and concentration of the metal inclusions. The manipulation of physical properties of nanoparticles changes their surface plasmon resonance (SPR) position and, respectively, optical properties of the composites. Controllable two-step fabrication of silver-glass composite by dry field-assisted ion-exchange with subsequent laser irradiation has been reported [6]. The main aim of this work is the study of the composite formation as the result of the interaction between ns-pulsed laser and silver ions embedded to the glass slide using “wet” silver-sodium ion-exchange. In this paper, we present the optical and structural properties of the nanocomposite. Experimental methods To embed silver ions into glass matrix, soda-lime glass slides were ion-exchanged in silver-sodium melt solution: 5%wt.AgNO3: 95%wt.NaNO3 for 20 min at 325°C. In the process sodium ions were replaced by silver ions in several microns deep subsurface layer of the glass. Prepared samples were irradiated by METANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121362      3rd harmonic of pulsed Nd:YVO4 laser (pulse length τ = 10 ns) at λ = 355 nm wavelength (edge of absorption of the glass) in standard atmospheric environment (room temperature and normal pressure). The laser beam had a Gaussian intensity profile and was focused onto the sample surface using a flat-field scanning lens system. The diameter of the focused spot (φ) was about 60 µm. Samples were irradiated with laser pulse repetition frequency of 80 kHz,  by scanning line-by-line with the speed of 1 mm/s (4800 pulse/spot). Laser output energy density (laser fluence) was varied from 332 to 197 mJ/cm2. The irradiated areas were characterized using Specord 50 spectrophotometer, Leica digital microscope, and a LEO 1550 Gemini scanning electron microscope (SEM). The list of prepared samples is presented in Table 1.  Table 1. The list of parameters of prepared samples Sample name #1 #2 #3 #4 Energy per pulse, μJ 9.38 9.00 6.94 5.56 Laser fluence, mJ/cm2 332 319 246 197 Results and discussions Photographs of the prepared samples are presented in Figs. 1,2. As seen, only particles on the glass surface were formed by laser pulses with the energy below ~6 μJ. Starting from 7 μJ energy of the irradiating pulses, bulk nanoparticles formation in the glass volume occurred Increasing pulse energy resulted in stronger reflection. At 9 μJ pulse energy the films started to become rough because of overheat resulted in bubbles and cracks formation near the glass surface.    Figure 1. Photos of the laser modified areas of the sample. From left to right areas #1 - #4. The sizes of the squares are 2.4x2.4 mm2. Images (a) and (b) were taken with different illumination.            Figure 2. Optical microscopy images of the samples taken with 5x magnification. Images (a-d) and (e-h) correspond to the samples #1 - #4. Images (a-d) were obtained in reflection mode and images (e-h) correspond to the transmission mode. The lines result from the scanning of the laser beam.  Optical absorption spectra of the irradiated areas are shown in Fig. 3. Optical density increases for higher irradiation laser power, which is also in accordance with Figs. 1,2. It is important to note that the peak of the absorption spectra lies at 440 nm wavelength, which is typical for spherical silver nanoparticles. Increase of the absorption means bigger amount of nanoparticles, while broadening of the absorption peak indicates broadening of the nanoparticles size distribution or an increase in their volume fraction. (a) (b) (c) (d) (e) (f) (g) (h) (a) (b) METANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121363      400 600 800 10000,00,51,01,52,02,5Absorption, a.u.Wavelength, nmfree Ion exchanged5.56 μJ6.94 μJ9.00 μJ9.38 μJIrradiation Figure 3. Optical absorption spectra. Figures near corresponding spectra indicate laser pulse energy.  SEM images taken in the centre of the irradiated lines show that under decreasing the laser power the average silver nanoparticle size drops from 15 to 10 nm. This is well correlated with optical spectroscopy data presented in Fig. 3.      Figure 4. SEM images of the samples taken in the center of the irradiated lines. Images (a-d) correspond to the samples #1 - #4.  The laser beam focused on the glass surface with the spot size of 60 µm creates ~60 µm wide line of nanoparticles when scanned. Silver nanoparticles up to 500 nm in size were grown at the border of this line. In Fig. 5 one can see the presence of nanoparticles outside the irradiated line. This line broadening is caused by laser heating of the glass surface, which results in the formation of silver nanoparticles in the glass bulk (about 60 µm  deep region – see Fig. 6) and on the glass surface near the irradiated area. The broadening of the line is about 30 µm from each side of the line. The size of silver nanoparticles outside the line is about 1.5-2 times bigger, and the nanoparticles are denser then inside of the irradiated area. This effect should be taken in account for line-by-line metallisation of a glass.   (a) (b) (c) (d) METANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121364         Figure 5. SEM of individual 60 µm-wide line drown by the laser on the sample #4 surface (a). Images taken inside the line (b), at the border of the line (c) and outside (d) the line.       Figure 6. SEM of the chipped glass (side view). One can see 60 microns thick region enriched with the nanoparticles. Conclusion The formation of silver nanoparticles in the glass embedded silver ions via classic wet ion-exchange under nanosecond (10 ns) pulsed Nd:YVO4 laser irradiation at 355 nm wavelength is demonstrated. Increase of the laser power resulted in the growth of the average nanoparticle size. This technique of controlled local formation of the nanoparticles by pulsed laser irradiation allows one to create complex patterns of closely-positioned nanoparticles in glasses containing silver ions. Acknowledgments I.R. thanks the support of his research visit to the University of Dundee for the experiments on laser modification of the samples by the University of Eastern Finland and Academy of Finland (grant #323052); preparation of the ion-exchanged glass samples and their characterization after the laser processing were supported by Russian Scientific Foundation (project #16-12-10044). References [1] Aslan K, McDonald K, Previte M J R, Zhang Y and Geddes C D 2008 Chem. Phys. Lett. 464 216–219 [2] Stenzel O and Macleod A 2012 Adv. Opt. Technol. 1 (6) 463–481 [3] De Julián Fernández C, et al. 2005 Sensors Actuators, B Chem. 111–112 225–229 [4] Inácio P L, Barreto B J, Horowitz F, Correia R R B and Pereira M B 2013 Opt. Mater. Express 3 (3) 390 [5] Xie X S and Dunn R C 1994 Science 265 361–364 [6] Wackerow S and Abdolvand A 2014 Opt. Express 22 (5) 5076  Surface (b) (c) (d) 60 µm  Cut (a) 

                                                                    University of DundeeNanosecond Laser Surface Silver Metallization of Wet Ion Exchanged GlassesReduto, I.; Wackerow, S.; Zolotovskaya, S; Abdolvand, A.; Lipovskii, A.; Svirko, YuPublished in:Journal of Physics: Conference SeriesDOI:10.1088/1742-6596/1461/1/012136Publication date:2020Licence:CC BYDocument VersionPublisher's PDF, also known as Version of recordLink to publication in Discovery Research PortalCitation for published version (APA):Reduto, I., Wackerow, S., Zolotovskaya, S., Abdolvand, A., Lipovskii, A., & Svirko, Y. (2020). Nanosecond LaserSurface Silver Metallization of Wet Ion Exchanged Glasses. In Journal of Physics: Conference Series:METANANO 2019 15-19 July 2019, St. Petersburg, Russian Federation (Vol. 1461, pp. 1-5). [012136] (Journalof Physics: Conference Series). IOP Publishing Ltd.. https://doi.org/10.1088/1742-6596/1461/1/012136General rightsCopyright and moral rights for the publications made accessible in Discovery Research Portal are retained by the authors and/or othercopyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated withthese rights. • Users may download and print one copy of any publication from Discovery Research Portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain. • You may freely distribute the URL identifying the publication in the public portal.Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Download date: 19. Apr. 2023Journal of Physics: Conference SeriesPAPER • OPEN ACCESSNanosecond Laser Surface Silver Metallization of Wet Ion ExchangedGlassesTo cite this article: I Reduto et al 2020 J. Phys.: Conf. Ser. 1461 012136 View the article online for updates and enhancements.This content was downloaded from IP address 2.121.108.145 on 07/05/2020 at 11:44Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing LtdMETANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121361      Nanosecond Laser Surface Silver Metallization of Wet Ion Exchanged Glasses I Reduto1,2,3, S Wackerow4, S Zolotovskaya4, A Abdolvand4, A Lipovskii2,3, Yu Svirko1 1Institute of Photonics, Department of Physics and Mathematics, University of Eastern Finland, Joensuu 80101, Finland  2Institute of Physics, Nanotechnology and Telecommunication, Peter the Great St. Petersburg Polytechnic University, St. Petersburg 195251, Russia  3Department of Physics and Technology of Nanostructures, St. Petersburg Academic University, Saint Petersburg 194021, Russia 4School of Engineering, Physics & Mathematics, University of Dundee, Dundee DD1 4HN, UK reduto-igor@mail.ru Abstract. Silver ions are embedded in glass slides by a traditional “wet” ion exchange technique. The glass slides irradiation by 10 ns laser pulses at 355 nm wavelength leads to the formation of metal-like film at the surface. Scanning electron microscopy shows that the films presents a dense layer of silver nanoparticles about the same size and separation. Varying the irradiation parameters results in a significant difference in the transmission spectra of the slides. Particle size grows when the laser power increases. Introduction Noble metal nanoparticles are interesting due to their unique nonlinear optical properties [1–3]. The optical properties of a glass embedded with silver nanoparticles can be controlled via varying physical properties of nanoparticles, and this makes the glass-metal nanocomposites promising candidates for numerous applications in optoelectronics [4] and sensing [5]. The optical properties of these glassy composites are dominated by the SPRs which are specific for different metals and different types of surrounding matrix, size, shape, spatial distribution and concentration of the metal inclusions. The manipulation of physical properties of nanoparticles changes their surface plasmon resonance (SPR) position and, respectively, optical properties of the composites. Controllable two-step fabrication of silver-glass composite by dry field-assisted ion-exchange with subsequent laser irradiation has been reported [6]. The main aim of this work is the study of the composite formation as the result of the interaction between ns-pulsed laser and silver ions embedded to the glass slide using “wet” silver-sodium ion-exchange. In this paper, we present the optical and structural properties of the nanocomposite. Experimental methods To embed silver ions into glass matrix, soda-lime glass slides were ion-exchanged in silver-sodium melt solution: 5%wt.AgNO3: 95%wt.NaNO3 for 20 min at 325°C. In the process sodium ions were replaced by silver ions in several microns deep subsurface layer of the glass. Prepared samples were irradiated by METANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121362      3rd harmonic of pulsed Nd:YVO4 laser (pulse length τ = 10 ns) at λ = 355 nm wavelength (edge of absorption of the glass) in standard atmospheric environment (room temperature and normal pressure). The laser beam had a Gaussian intensity profile and was focused onto the sample surface using a flat-field scanning lens system. The diameter of the focused spot (φ) was about 60 µm. Samples were irradiated with laser pulse repetition frequency of 80 kHz,  by scanning line-by-line with the speed of 1 mm/s (4800 pulse/spot). Laser output energy density (laser fluence) was varied from 332 to 197 mJ/cm2. The irradiated areas were characterized using Specord 50 spectrophotometer, Leica digital microscope, and a LEO 1550 Gemini scanning electron microscope (SEM). The list of prepared samples is presented in Table 1.  Table 1. The list of parameters of prepared samples Sample name #1 #2 #3 #4 Energy per pulse, μJ 9.38 9.00 6.94 5.56 Laser fluence, mJ/cm2 332 319 246 197 Results and discussions Photographs of the prepared samples are presented in Figs. 1,2. As seen, only particles on the glass surface were formed by laser pulses with the energy below ~6 μJ. Starting from 7 μJ energy of the irradiating pulses, bulk nanoparticles formation in the glass volume occurred Increasing pulse energy resulted in stronger reflection. At 9 μJ pulse energy the films started to become rough because of overheat resulted in bubbles and cracks formation near the glass surface.    Figure 1. Photos of the laser modified areas of the sample. From left to right areas #1 - #4. The sizes of the squares are 2.4x2.4 mm2. Images (a) and (b) were taken with different illumination.            Figure 2. Optical microscopy images of the samples taken with 5x magnification. Images (a-d) and (e-h) correspond to the samples #1 - #4. Images (a-d) were obtained in reflection mode and images (e-h) correspond to the transmission mode. The lines result from the scanning of the laser beam.  Optical absorption spectra of the irradiated areas are shown in Fig. 3. Optical density increases for higher irradiation laser power, which is also in accordance with Figs. 1,2. It is important to note that the peak of the absorption spectra lies at 440 nm wavelength, which is typical for spherical silver nanoparticles. Increase of the absorption means bigger amount of nanoparticles, while broadening of the absorption peak indicates broadening of the nanoparticles size distribution or an increase in their volume fraction. (a) (b) (c) (d) (e) (f) (g) (h) (a) (b) METANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121363      400 600 800 10000,00,51,01,52,02,5Absorption, a.u.Wavelength, nmfree Ion exchanged5.56 μJ6.94 μJ9.00 μJ9.38 μJIrradiation Figure 3. Optical absorption spectra. Figures near corresponding spectra indicate laser pulse energy.  SEM images taken in the centre of the irradiated lines show that under decreasing the laser power the average silver nanoparticle size drops from 15 to 10 nm. This is well correlated with optical spectroscopy data presented in Fig. 3.      Figure 4. SEM images of the samples taken in the center of the irradiated lines. Images (a-d) correspond to the samples #1 - #4.  The laser beam focused on the glass surface with the spot size of 60 µm creates ~60 µm wide line of nanoparticles when scanned. Silver nanoparticles up to 500 nm in size were grown at the border of this line. In Fig. 5 one can see the presence of nanoparticles outside the irradiated line. This line broadening is caused by laser heating of the glass surface, which results in the formation of silver nanoparticles in the glass bulk (about 60 µm  deep region – see Fig. 6) and on the glass surface near the irradiated area. The broadening of the line is about 30 µm from each side of the line. The size of silver nanoparticles outside the line is about 1.5-2 times bigger, and the nanoparticles are denser then inside of the irradiated area. This effect should be taken in account for line-by-line metallisation of a glass.   (a) (b) (c) (d) METANANO 2019IOP Conf. Series: Journal of Physics: Conf. Series 1461 (2020) 012136IOP Publishingdoi:10.1088/1742-6596/1461/1/0121364         Figure 5. SEM of individual 60 µm-wide line drown by the laser on the sample #4 surface (a). Images taken inside the line (b), at the border of the line (c) and outside (d) the line.       Figure 6. SEM of the chipped glass (side view). One can see 60 microns thick region enriched with the nanoparticles. Conclusion The formation of silver nanoparticles in the glass embedded silver ions via classic wet ion-exchange under nanosecond (10 ns) pulsed Nd:YVO4 laser irradiation at 355 nm wavelength is demonstrated. Increase of the laser power resulted in the growth of the average nanoparticle size. This technique of controlled local formation of the nanoparticles by pulsed laser irradiation allows one to create complex patterns of closely-positioned nanoparticles in glasses containing silver ions. Acknowledgments I.R. thanks the support of his research visit to the University of Dundee for the experiments on laser modification of the samples by the University of Eastern Finland and Academy of Finland (grant #323052); preparation of the ion-exchanged glass samples and their characterization after the laser processing were supported by Russian Scientific Foundation (project #16-12-10044). References [1] Aslan K, McDonald K, Previte M J R, Zhang Y and Geddes C D 2008 Chem. Phys. Lett. 464 216–219 [2] Stenzel O and Macleod A 2012 Adv. Opt. Technol. 1 (6) 463–481 [3] De Julián Fernández C, et al. 2005 Sensors Actuators, B Chem. 111–112 225–229 [4] Inácio P L, Barreto B J, Horowitz F, Correia R R B and Pereira M B 2013 Opt. Mater. Express 3 (3) 390 [5] Xie X S and Dunn R C 1994 Science 265 361–364 [6] Wackerow S and Abdolvand A 2014 Opt. Express 22 (5) 5076  Surface (b) (c) (d) 60 µm  Cut (a) 

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Nanosecond Laser Surface Silver Metallization of Wet Ion Exchanged Glasses

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