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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 12 — Jun. 17, 2013
  • pp: 14282–14290
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Surface enhanced Raman scattering and plasmon enhanced fluorescence in zinc-tellurite glass

Raja J. Amjad, M. R. Sahar, M. R. Dousti, S. K. Ghoshal, and M. N. A. Jamaludin  »View Author Affiliations


Optics Express, Vol. 21, Issue 12, pp. 14282-14290 (2013)
http://dx.doi.org/10.1364/OE.21.014282


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Abstract

We report significant enhancements in Er3+ luminescence as well as in Raman intensity in silver nanoparticles embedded zinc-tellurite glass. Surface enhanced Raman scattering effect is highlighted for the first time in tellurite glass containing silver NPs resulting in an enhanced Raman signal (~10 times). SAED manifest the growth of Ag0 nanoparticles along the (111) and (200) crystallographic planes having average diameter in the range 14-36 nm. Surface plasmon resonance bands are observed in the range 484-551 nm. Furthermore, four prominent photoluminescence bands undergo significant enhancements up to 3 times. The enhancement is majorly attributed to the local field effect of silver NPs.

© 2013 OSA

1. Introduction

Due to the distinctive characteristic of resonant absorption displayed by different glasses when nano-sized structures (usually metals or semiconductors) are incorporated are getting large interest recently [1

1. M. Fujii, M. Yoshida, Y. Kanzawa, S. Hayashi, and K. Yamamoto, “1.54 μm photoluminescence of Er3+ doped into SiO2 films containing Si nanocrystals: Evidence for energy transfer from Si nanocrystals to Er3+,” Appl. Phys. Lett. 71(9), 1198–1200 (1997). [CrossRef]

3

3. S. Ju, V. L. Nguyen, P. R. Watekar, B. H. Kim, C. Jeong, S. Boo, C. J. Kim, and W. T. Han, “Fabrication and optical characteristics of a novel optical fiber doped with the Au nanoparticles,” J. Nanosci. Nanotechnol. 6(11), 3555–3558 (2006). [CrossRef] [PubMed]

]. It is well known that emission cross-section for Er3+ is small hence there is ways to enhance it for different applications. One way is to co-doped with another rare-earth (RE) like Yb [4

4. M. P. Hehlen, N. J. Cockroft, T. R. Gosnell, and A. J. Bruce, “Spectroscopic properties of Er3+ and Yb3+doped soda-lime silicate and aluminosilicate glasses,” Phys. Rev. B 56(15), 9302–9318 (1997). [CrossRef]

], another strategy is to embed with semiconductor nanostructures like Si [2

2. S. Moon, P. R. Watekar, B. H. Kim, and W. T. Han, “Fabrication and photoluminescence characteristics of Er3+-doped optical fibre sensitised by silicon,” Electron. Lett. 43(2), 85–87 (2007). [CrossRef]

] and more lately embedding metallic nanoparticles (NPs) like Ag or Au [5

5. C. Strohhofer and A. Polman, “Silver as a sensitizer for erbium,” Appl. Phys. Lett. 81(8), 1414–1416 (2002). [CrossRef]

]. Collective oscillation of free electrons is called surface Plasmon resonance (SPR). SPR gives origin to large and highly confined local electric field within the proximity of metal NPs [6

6. S. A. Maier and H. A. Atwater, “Plasmonics: Localization and guiding of electromagnetic energy in metal/dielectric structures,” J. Appl. Phys. 98(1), 011101 (2005). [CrossRef]

, 7

7. W. L. Barnes, A. Dereux, and T. W. Ebbesen, “Surface plasmon subwavelength optics,” Nature 424(6950), 824–830 (2003). [CrossRef] [PubMed]

]. These metallic NPs (plasmonic nanostructures) when lie within the vicinity of the RE ion can enhance the luminescence yield by several order of magnitude due to the local field effect (LFE) induce by SPR [8

8. C. D. Geddes and J. R. Lakowicz, “Editorial: Metal-enhanced fluorescence,” J. Fluoresc. 12(2), 121–129 (2002). [CrossRef] [PubMed]

, 9

9. K. Aslan, I. Gryczynski, J. Malicka, E. Matveeva, J. R. Lakowicz, and C. D. Geddes, “Metal-enhanced fluorescence: an emerging tool in biotechnology,” Curr. Opin. Biotechnol. 16(1), 55–62 (2005). [CrossRef] [PubMed]

]. This mechanism is known as metal enhanced luminescence (MEL) which is a powerful tool not only in biotechnology [8

8. C. D. Geddes and J. R. Lakowicz, “Editorial: Metal-enhanced fluorescence,” J. Fluoresc. 12(2), 121–129 (2002). [CrossRef] [PubMed]

, 9

9. K. Aslan, I. Gryczynski, J. Malicka, E. Matveeva, J. R. Lakowicz, and C. D. Geddes, “Metal-enhanced fluorescence: an emerging tool in biotechnology,” Curr. Opin. Biotechnol. 16(1), 55–62 (2005). [CrossRef] [PubMed]

] but also in the novel field of nanophotonics [10

10. A. V. Zayats, I. I. Smolyaninov, and A. A. Maradudin, “Nano-optics of surface plasmon polaritons,” Phys. Rep. 408(3-4), 131–314 (2005). [CrossRef]

]. For conducting fluorescence experiments, the geometry of the specimen should be large enough when comparing with the dimension of fluorophores and relative to the emission and absorption wavelengths [9

9. K. Aslan, I. Gryczynski, J. Malicka, E. Matveeva, J. R. Lakowicz, and C. D. Geddes, “Metal-enhanced fluorescence: an emerging tool in biotechnology,” Curr. Opin. Biotechnol. 16(1), 55–62 (2005). [CrossRef] [PubMed]

]. Fluorophores emits radiations into free space in this case which is the usual observation. However, the existence of small metallic NPs can modify the free space situation and can cause remarkable optical alteration. Surprisingly, there may be increase or decrease in the radiative decay rates of fluorophores due to metal surfaces which can enhance the rate of resonance energy transfer [11

11. J. R. Lakowicz, “Radiative decay engineering: biophysical and biomedical applications,” Anal. Biochem. 298(1), 1–24 (2001). [CrossRef] [PubMed]

, 12

12. J. R. Lakowicz, Y. Shen, S. D’Auria, J. Malicka, J. Fang, Z. Gryczynski, and I. Gryczynski, “Radiative decay engineering. 2. Effects of silver island films on fluorescence intensity, lifetimes, and resonance energy transfer,” Anal. Biochem. 301(2), 261–277 (2002). [CrossRef] [PubMed]

]. When fluorophores in excited states interact with free electrons of the metal (so called surface Plasmon electrons) induce modifying effect on the fluorophore. The interaction between fluorophore and metal is referred as metal-enhanced fluorescence (MEF) in the field of biotechnology. In telecommunications, for data transfer optical fibres are used, however due to scattering, absorption and impurities optical signal can be attenuated. To overcome these problems Erbium doped fibre amplifiers were developed and other possibility is Raman Amplifier utilizing stimulated Raman scattering [13

13. E. B. Desurvire, “Capacity demand and technology challenges for lightwave systems in the next two decades,” J. Lightwave Technol. 24(12), 4697–4710 (2006). [CrossRef]

].

The aim of the present study is to investigate the effect of SPR of metallic NPs on the photoluminescence and Raman signal in erbium-zinc-tellurite glass. To our knowledge only few studies are found in literature with enhancement in Raman signal when embedding metallic NPs inside the glass host [14

14. J. A. García-Macedo, G. Valverde, J. Lockard, and J. I. Zink, “SERS on mesostructured thin films with silver nanoparticles,” Proc. SPIE 5361, 117–124 (2004). [CrossRef]

,15

15. D. Roy, Z. H. Barber, and T. W. Clyne, “Ag nanoparticle induced surface enhanced Raman spectroscopy of chemical vapor deposition diamond thin films prepared by hot filament chemical vapor deposition,” J. Appl. Phys. 91(9), 6085–6088 (2002). [CrossRef]

].

2. Experimental work

3. Results and discussion

Figure 1
Fig. 1 (a) Absorption spectra of Er3+ doped tellurite glass for No AgCl (Glass A) and 1.0 mol% AgCl (Glass D). Inset shows surface plasmon resonance (SPR) band located at 484 nm for Glass E. Energy levels are numbered as (1-4I13/2, 2-4I11/2, 3-4I9/2, 4-4F9/2, 5-2H11/2, 6-4F7/2, 7-2G9/2) (b) SPR bands observed for glass samples G, H and I centered at 490, 521, 551 nm.
shows the UV-Vis-NIR absorption spectra of all the glass samples. Surface Plasmon resonance (SPR) band due to silver NPs is not observed in the samples containing both Er3+ and Ag, therefore one Er3+ free sample containing 0.5 mol% of AgCl is prepared in order to monitor SPR band. The band around 484 nm belongs to the surface Plasmon absorption of pure 0.5 mol% Ag (inset Fig. 1). The maxima of SPR band is strongly dependent upon the refractive index (RI, n) of the glass according to Mie theory as follows
λmax2=(2πc)2mNe2(ε+2n2)/ε0
(1)
here c is the speed of light, N is the concentration of free electrons, m is conduction electrons’ effective mass, ε0 is the permeability of free space and ε is the metal optical dielectric function. In case of sodalime silicate glasses with RI~1.5, SPR bands of Ag0 and Au0 NPs are found to be positioned at 410 and 520 nm, respectively [16

16. F. Gonella and P. Mazzoldi, “Metal nanocluster composite glasses,” in Handbook of Nanostructured Materials and Nanotechnology, Nalwa HS (Ed), vol 4. (Academic, 2000).

]. It is well known that if the RI of the matrix is higher, then SPR band will move to longer wavelength [17

17. T. Som and B. Karmakar, “Core shell Au Ag Nanoparticles in Dielectric Nanocomposites with Plasmon-Enhanced Fluorescence: A New Paradigm in Antimony Glasses,” Nano Res. 2(8), 607–616 (2009). [CrossRef]

]. Since, in our case the RI of zinc-tellurite glass is ~2.4, hence SPR is prominently red-shifted to 484 nm.

Altering the annealing time and AgCl concentration modifies the optical properties. It is known that as the inter-particle spacing becomes smaller, interactions (efficient surface plasmon coupling) between the closely spaced metallic NPs significantly generates enhanced localized electric field hence luminescence intensity can be increased by many folds.

The plasmon peak is known to depend upon the refractive index as well as on the concentration of metallic NPs inside the glass host. We have prepared three Er3+ free samples [Glass G, H and I] to monitor the behavior of plasmon peak and its influence upon enhanced luminescence. Consequently, it has been found that this peak is red shifted from 490 nm to 551 nm for samples G to I, respectively, manifesting the formation of larger non-spherical silver NPs [18

18. T. Som and B. Karmakar, “Surface Plasmon Resonance and Enhanced Fluorescence Application of Single-Step Synthesized Elliptical Nano Gold-embedded Antimony Glass Dichroic Nanocomposites,” Plasmonics 5(2), 149–159 (2010). [CrossRef]

]. These non-spherical and asymmetric NPs are also evidenced from TEM image (Fig. 2
Fig. 2 (a) shows the selected area electron diffraction (SAED) of glass C. The high resolution transmission electron microscope (HR-TEM) image of one single NP is shown in Fig. 2(b). Figures 2((c), (d), (e)) shows the TEM images of the glass samples C, D and E respectively. Corresponding histograms for the size distribution is also shown down to each TEM. Average diameter of NPs for glass B, C and D is 14, 24 and 36 nm respectively.
).

At higher concentration of Ag and maximum annealing time above glass transition temperature (24 Hrs) several NPs approach closely or coalesces (Ostwald’s ripening), so that their induced electric fields are expected to overlie and produce “hot spots” regions (or the regions of stronger electric field) that leads to a stronger surface enhanced fluorescence [7

7. W. L. Barnes, A. Dereux, and T. W. Ebbesen, “Surface plasmon subwavelength optics,” Nature 424(6950), 824–830 (2003). [CrossRef] [PubMed]

].

Figure 2(a) shows the selected area electron diffraction (SAED) of glass C. The high resolution transmission electron microscope (HRTEM) image of one single NP is shown in Fig. 2 (b). Figures 2(c)-2(e) show the transmission electron microscope (TEM) images of the glass samples C, D and E respectively. Corresponding histograms for the size distribution of the NPs are also given. Average diameter of NPs for glass B, C and D is 14, 24 and 36 nm respectively. It is clear from the size distribution that as the concentration of silver NPs is increased, their average size is also increased.

The increased average size of NPs by further introduction of NPs can be attributed to the growth of NPs during heat treatment by the following mechanisms (A) Ostwald ripening, where atoms or small clusters of atoms diffuse from smaller to larger NPs, and (B) nanoparticle migration followed by coalescence. i.e. at higher concentration of silver NPs (0.5 and 1.0 mol%) quite a few NPs approach closely or coalesces (Ostwald’s ripening) (see Fig. 3
Fig. 3 (A) Ostwald ripening (B) nanoparticle migration followed by coalescence.
). Average diameter of the Ag nanocrystallites is found to be varied in the range of 14–36 nm.

Figure 4
Fig. 4 Raman spectra for Er3+ doped glass samples
presents the Raman spectra of all the Er3+ doped glass samples. The peaks centered at 281, 367 and 601 cm−1 belongs to the linkages in the bulk matrix. After embedding silver NPs inside the glass matrix the intensity of all these peaks are enhanced drastically (~by a factor of 10 times). These results are quite interesting and relatively new. The peak around at 601 cm−1 may be contributed from TeO2 units [19

19. T. Sekiya, N. Mochida, A. Ohtsuka, and A. Soejima, “Raman spectra of BO3/2-TeO2 glasses,” J. Non-Cryst. Solids 151(3), 222–228 (1992). [CrossRef]

]. In the lower frequency, the peak at 281 cm−1 is assigned to both TeO3 tp and Er–O bond [20

20. T. Komatsu, H. Tawarayama, H. Mohri, and K. Matusita, “Properties and crystallization behaviors of TeO2-LiNbO3 glasses,” J. Non-Cryst. Solids 135(2-3), 105–113 (1991). [CrossRef]

], and the peaks around 336, 367 are assigned to Zn-O [21

21. K. A. Alim, V. A. Fonoberov, M. Shamsa, and A. A. Balandin, “Micro-Raman investigation of optical phonons in ZnO nanocrystals,” J. Appl. Phys. 97(12), 124313 (2005). [CrossRef]

].

Fleischmann in 1974 [22

22. M. Fleischmann, P. J. Hendra, and A. J. McQuillan, “Raman spectra of pyridine adsorbed at a silver electrode,” Chem. Phys. Lett. 26(2), 163–166 (1974). [CrossRef]

] observed the phenomenon of SERS for the first time and was elucidated as a consequence of the interaction between a molecule and the metal plasmon three years later [23

23. E. Nardou, D. Vouagner, A.-M. Jurdyc, A. Berthelot, A. Pillonnet, V. Sablonière, F. Bessueille, and B. Champagnon, “Surface enhanced Raman scattering in an amorphous matrix for Raman amplification,” J. Non-Cryst. Solids 357(8-9), 1895–1899 (2011). [CrossRef]

]. The EM field exaltation and the polarizability tensor exaltation are the two main theories that describe the SERS effect. An EM field is generated when the incident EM field frequency becomes in resonance to the frequency of SP. This allows the strengthening of the incident field and exalts the Raman scattering of the studied molecule. Raman scattering is also enhanced due to its correspondence with SPR frequency and consequently there is a double exaltation effect [24

24. K. Kneipp, “Surface-enhanced Raman scattering ,” Phys. Today, 40–46 (2007).

, 25

25. M. K. Hossain and Y. Ozaki, “Surface-enhanced Raman scattering: facts and inline trends,” Curr. Sci. 97, 192–201 (2009).

]. In SERS chemical effect (polarizability tensor exaltation) is also involved. Structure of the molecule can be modified by this effect causing a frequency shift of Raman scattering [26

26. A. M. Michaels, M. Nirmal, and L. E. Brus, “Surface enhanced Raman spectroscopy of individual rhodamine 6G molecules on large Ag nanocrystals,” J. Am. Chem. Soc. 121(43), 9932–9939 (1999). [CrossRef]

28

28. A. Otto, I. Mrozek, H. Grabhorn, and W. Akemann, “Surface-enhanced Raman scattering,” Condens. Matter. 4(5), 1143–1212 (1992). [CrossRef]

]. Furthermore, the topological variations of NPs in dielectrics promote the local electric field further by lightening rod effects (LRE) at surface of non-spherical NPs (elliptical, cube, pyramid shapes and so on) which can enhance the intensity of scattered Raman signal up to 1014 times [29

29. S. Nie and S. R. Emory, “Probing single molecules and single nanoparticles by surface-enhanced Raman scattering,” Science 275(5303), 1102–1106 (1997). [CrossRef] [PubMed]

].

Figure 5(a)
Fig. 5 (a) luminescence spectra of glasses under an excitation of 786 nm i) No AgCl, ii) 0.1 mol% AgCl, iii) 0.5 mol% AgCl, iv) 1.0 mol% AgCl (b) plot of emission intensity vs concentration of Ag (mol%). Maximum amplification for the green and red bands is found to occur at 0.5 mol% Ag (Glass C).
shows the PL of the studied glasses; four prominent emission bands are obtained located at 520 nm, 550 nm, 650 nm and 835 nm attributed to 2H11/24I15/2, 4S3/24I15/2, 4F9/24I15/2 and 4S3/24I13/2 transitions, respectively. All the bands are enhanced significantly by factors of 2.5, 2.3, 2 and 1.7 times, respectively (See Fig. 5(b)).

The metallic NPs result in large and highly localized electric field around the Er3+ ions [30

30. R. J. Amjad, M. R. Sahar, S. K. Ghoshal, M. R. Dousti, S. Riaz, A. R. Samavati, R. Arifin, and S. Naseem, “Annealing time dependent up-conversion luminescence enhancement in magnesium–tellurite glass,” J. Lumin. 136, 145–149 (2013). [CrossRef]

33

33. L. R. P. Kassab, F. A. Bomfim, J. R. Martinelli, N. U. Wetter, J. J. Neto, and C. B. de Araújo, “Energy transfer and frequency upconversion in Yb3+–Er3+-doped PbO- GeO2 glass containing silver nanoparticles,” Appl. Phys. B 94(2), 239–242 (2009). [CrossRef]

]. As, surface plasmon polariton generated by electronic oscillations (SPR) move along the surface of metallic NPs focus light in the subwavelength structures due to the difference in relative permittivity of the surrounding host and metal. Furthermore, the local field around the metallic NPs is enhanced by the concentration of light and metallic screening (“Lightning Rod Effect”) with respect to the incident field [34

34. F. Le, D. W. Brandl, Y. A. Urzhumov, H. Wang, J. Kundu, N. J. Halas, J. Aizpurua, and P. Nordlander, “Metallic Nanoparticle Arrays: A common substrate for both surface-enhanced Raman scattering and surface-enhanced infrared absorption,” ACS Nano 2(4), 707–718 (2008). [CrossRef] [PubMed]

, 35

35. O. L. Malta and M. A. dos Santos, “Theoretical analysis of the fluorescence yield of rare earth ions in glasses containing small metallic particles,” Chem. Phys. Lett. 174(1), 13–18 (1990). [CrossRef]

]. Nevertheless, metallic NPs offer a unique prospect of modification of fluorescence due to changes in the rates of excitation and emission of lanthanide ions. If the host is a glass then the effect of metallic NPs on the emission and absorption rates of lanthanide ions is primarily of electronic origin [36

36. T. Hayakawa, S. T. Selvan, and M. Nogami, “Field enhancement effect of small Ag particles on the fluorescence from Eu3+-doped SiO2 glass,” Appl. Phys. Lett. 74(11), 1513–1515 (1999). [CrossRef]

, 37

37. C. D. Geddes, I. Gryczynski, J. Malicka, Z. Gryczynski, and J. R. Lakowicz, “Metal-enhanced fluorescence: Potential applications in HTS,” Comb. Chem. High Throughput Screen. 6(2), 109–117 (2003). [CrossRef] [PubMed]

]. It can be visualized as an added interaction in the proximity of metallic NPs generated by plasmonic excitation at the Mie resonance frequency [36

36. T. Hayakawa, S. T. Selvan, and M. Nogami, “Field enhancement effect of small Ag particles on the fluorescence from Eu3+-doped SiO2 glass,” Appl. Phys. Lett. 74(11), 1513–1515 (1999). [CrossRef]

, 37

37. C. D. Geddes, I. Gryczynski, J. Malicka, Z. Gryczynski, and J. R. Lakowicz, “Metal-enhanced fluorescence: Potential applications in HTS,” Comb. Chem. High Throughput Screen. 6(2), 109–117 (2003). [CrossRef] [PubMed]

].

Even though enhanced quantum yield is desirable, however both enhancement and quenching of fluorophore is observed near the metallic NPs [38

38. J. Zhu, “SPR induced quenching of the 5D17F1 emission of Eu3+ doped gold colloids,” Phys. Lett. A 341(1-4), 212–215 (2005). [CrossRef]

, 39

39. E. G. Matveeva, T. Shtoyko, I. Gryczynski, I. Akopova, and Z. Gryczynski, “Fluorescence quenching/enhancement surface assays: Signal manipulation using silver-coated gold nanoparticles,” Chem. Phys. Lett. 454(1-3), 85–90 (2008). [CrossRef] [PubMed]

]. If the distance between metallic NP and fluorophore is 50 Å or more then enhancement in fluorescence can be achieved [37

37. C. D. Geddes, I. Gryczynski, J. Malicka, Z. Gryczynski, and J. R. Lakowicz, “Metal-enhanced fluorescence: Potential applications in HTS,” Comb. Chem. High Throughput Screen. 6(2), 109–117 (2003). [CrossRef] [PubMed]

]. Enhancement in fluorescence can be maximized in some regions near metal surface due to the exponential decrease of the local field from the surface [35

35. O. L. Malta and M. A. dos Santos, “Theoretical analysis of the fluorescence yield of rare earth ions in glasses containing small metallic particles,” Chem. Phys. Lett. 174(1), 13–18 (1990). [CrossRef]

, 37

37. C. D. Geddes, I. Gryczynski, J. Malicka, Z. Gryczynski, and J. R. Lakowicz, “Metal-enhanced fluorescence: Potential applications in HTS,” Comb. Chem. High Throughput Screen. 6(2), 109–117 (2003). [CrossRef] [PubMed]

].

Ground state absorption (GSA), excited state absorption (ESA) and energy transfer upconversion (ETU) are the vital involved mechanisms. These mechanisms can be explained as follows
4I15/24I9/2[GSA]4I11/2[NR] 4F7/2[ESA]2H11/2[NR]4S3/2
(2)
where NR is the non-radiative decay. Moreover, ETU also takes place as follows (See Fig. 7(a)).

(4I11/2,4I11/2)(4I15/2,4F7/2)
(3)
(4I11/2,4I13/2)(4I15/2,4F9/2)
(4)

Downconversion emission spectra of Er3+ doped tellurite glass samples with and without silver NPs are shown in Fig. 6
Fig. 6 (a) Downconversion luminescence spectra of glasses with i) No AgCl, ii) 0.1 mol% AgCl, iii) 0.5 mol% AgCl, iv) 1.0 mol% AgCl (b) plot of emission intensity vs concentration of Ag (mol%). Maximum amplification for the green and red bands are found to be occur at 0.5 mol% Ag (Glass C).
. For all the glass samples the excitation wavelength used is 470 nm. Four prominent emission bands are obtained centered at 520 nm, 550 nm, 650 nm and 835 nm attributed to 2H11/24I15/2, 4S3/24I15/2, 4F9/24I15/2 and4S3/24I13/2 transitions, respectively. All the bands are enhanced gradually (by factors of 3, 2.7, 2 and 2.8). Involved mechanisms can be understood similar to upconversion enhancement (see Fig. 7(b)
Fig. 7 (a) Partial energy level diagram of Er3+ ions in zinc-tellurite glass showing UC emissions at 520, 550 and 650 nm through ground state absorption (GSA), excited state absorption (ESA) and energy transfer (ET) between two Er3+ ions. Local field effects due to silver NPs are also shown. (b) Partial energy level diagram of Er3+ ions in zinc-tellurite glass showing downconversion emission at 520, 550, 650 and 835 nm through ground state absorption (GSA) and energy transfer (ET) between two Er3+ ions. Local field effects due to silver NPs are also shown (b).
).

The effect of metallic NPs on the Eu3+ luminescence in glass and glass ceramics were studied for the first time by Malta et. al. [35

35. O. L. Malta and M. A. dos Santos, “Theoretical analysis of the fluorescence yield of rare earth ions in glasses containing small metallic particles,” Chem. Phys. Lett. 174(1), 13–18 (1990). [CrossRef]

] and later on confirmed by Hayakawa et. al. [36

36. T. Hayakawa, S. T. Selvan, and M. Nogami, “Field enhancement effect of small Ag particles on the fluorescence from Eu3+-doped SiO2 glass,” Appl. Phys. Lett. 74(11), 1513–1515 (1999). [CrossRef]

] Malta et al. [35

35. O. L. Malta and M. A. dos Santos, “Theoretical analysis of the fluorescence yield of rare earth ions in glasses containing small metallic particles,” Chem. Phys. Lett. 174(1), 13–18 (1990). [CrossRef]

] studied the results theoretically and suggested two possible mechanisms: one is the enhanced local field effect in the vicinity of Eu3+ ions and other is the energy transfer between Eu3+ ions and silver NPs.

So it can be concluded that the overall enhancement in the emisission bands of Er3+ is due to the sum of the following two processes

  • Local field effect around the rare-earth ions
  • The energy transfer from fluorescent Ago → Er3+

At maximum concentration of AgCl (1.0 mol%), a quench is observed in both up and down conversion fluorescence intensity. The reason for quenching is the energy transfer from Er3+ ions to silver NPs (Er3+→Ag0) and reabsorption by SPR of increased quantity of silver NPs having a plasmon absorption band range extended over the emission peak position of Er3+ [40

40. T. Som and B. Karmakar, “Nanosilver enhanced upconversion fluorescence of erbium ions in Er3+: Ag-antimony glass nanocomposites,” J. Appl. Phys. 105(1), 013102 (2009). [CrossRef]

, 41

41. V. A. G. Rivera, S. P. A. Osorio, Y. Ledemi, D. Manzani, Y. Messaddeq, L. A. O. Nunes, and E. Marega Jr., “Localized surface plasmon resonance interaction with Er3+-doped tellurite glass,” Opt. Express 18(24), 25321–25328 (2010). [CrossRef] [PubMed]

].

The schematic interaction of the indicent light by Er-Ag couple and visible emissions of the rare earth is presented in Fig. 8
Fig. 8 Red and green emissions from Er3+ under an excitation of 786 nm.
.

4. Conclusion

Melt-quench technique has been used to synthesize a series of Ag nanoparticles embedded zinc-tellurite glass. UV-vis absorption spectroscopy shows the plasmon band position in the range of 484-551 nm. The TEM images confirm the existence of spherical as well as anisotropic Ag nanoparticles inside the glass matrices. The growth of Ag0 nanoparticles along the (111) and (200) crystallographic planes is evident from SAED. Under an excitation wavelength of 786 nm, four prominent emission bands are obtained located at 520, 550, 650 and 835 nm attributed to 2H11/24I15/2, 4S3/24I15/2, 4F9/24I15/2 and 4S3/24I13/2 transitions respectively. All the bands are enhanced gradually (by factors of 2.47, 2.3, 2 and 1.7 times respectively). The enhancement is mainly attributed to the local field effect of silver NPs. Raman signal is amplified by a factor of 10 times for Glass D relative to Glass A due to the large electric field originated from the silver NPs. Enhanced fluorescence influenced by silver NPs may contribute towards the development of optical displays, laser and optical memory devices whereas amplification in Raman signal is promising for Raman amplifiers.

Acknowledgments

The authors gratefully acknowledge the financial supports from UTM through RUG 06J39 and ministry of higher education through FRGS 4F083.

References and links

1.

M. Fujii, M. Yoshida, Y. Kanzawa, S. Hayashi, and K. Yamamoto, “1.54 μm photoluminescence of Er3+ doped into SiO2 films containing Si nanocrystals: Evidence for energy transfer from Si nanocrystals to Er3+,” Appl. Phys. Lett. 71(9), 1198–1200 (1997). [CrossRef]

2.

S. Moon, P. R. Watekar, B. H. Kim, and W. T. Han, “Fabrication and photoluminescence characteristics of Er3+-doped optical fibre sensitised by silicon,” Electron. Lett. 43(2), 85–87 (2007). [CrossRef]

3.

S. Ju, V. L. Nguyen, P. R. Watekar, B. H. Kim, C. Jeong, S. Boo, C. J. Kim, and W. T. Han, “Fabrication and optical characteristics of a novel optical fiber doped with the Au nanoparticles,” J. Nanosci. Nanotechnol. 6(11), 3555–3558 (2006). [CrossRef] [PubMed]

4.

M. P. Hehlen, N. J. Cockroft, T. R. Gosnell, and A. J. Bruce, “Spectroscopic properties of Er3+ and Yb3+doped soda-lime silicate and aluminosilicate glasses,” Phys. Rev. B 56(15), 9302–9318 (1997). [CrossRef]

5.

C. Strohhofer and A. Polman, “Silver as a sensitizer for erbium,” Appl. Phys. Lett. 81(8), 1414–1416 (2002). [CrossRef]

6.

S. A. Maier and H. A. Atwater, “Plasmonics: Localization and guiding of electromagnetic energy in metal/dielectric structures,” J. Appl. Phys. 98(1), 011101 (2005). [CrossRef]

7.

W. L. Barnes, A. Dereux, and T. W. Ebbesen, “Surface plasmon subwavelength optics,” Nature 424(6950), 824–830 (2003). [CrossRef] [PubMed]

8.

C. D. Geddes and J. R. Lakowicz, “Editorial: Metal-enhanced fluorescence,” J. Fluoresc. 12(2), 121–129 (2002). [CrossRef] [PubMed]

9.

K. Aslan, I. Gryczynski, J. Malicka, E. Matveeva, J. R. Lakowicz, and C. D. Geddes, “Metal-enhanced fluorescence: an emerging tool in biotechnology,” Curr. Opin. Biotechnol. 16(1), 55–62 (2005). [CrossRef] [PubMed]

10.

A. V. Zayats, I. I. Smolyaninov, and A. A. Maradudin, “Nano-optics of surface plasmon polaritons,” Phys. Rep. 408(3-4), 131–314 (2005). [CrossRef]

11.

J. R. Lakowicz, “Radiative decay engineering: biophysical and biomedical applications,” Anal. Biochem. 298(1), 1–24 (2001). [CrossRef] [PubMed]

12.

J. R. Lakowicz, Y. Shen, S. D’Auria, J. Malicka, J. Fang, Z. Gryczynski, and I. Gryczynski, “Radiative decay engineering. 2. Effects of silver island films on fluorescence intensity, lifetimes, and resonance energy transfer,” Anal. Biochem. 301(2), 261–277 (2002). [CrossRef] [PubMed]

13.

E. B. Desurvire, “Capacity demand and technology challenges for lightwave systems in the next two decades,” J. Lightwave Technol. 24(12), 4697–4710 (2006). [CrossRef]

14.

J. A. García-Macedo, G. Valverde, J. Lockard, and J. I. Zink, “SERS on mesostructured thin films with silver nanoparticles,” Proc. SPIE 5361, 117–124 (2004). [CrossRef]

15.

D. Roy, Z. H. Barber, and T. W. Clyne, “Ag nanoparticle induced surface enhanced Raman spectroscopy of chemical vapor deposition diamond thin films prepared by hot filament chemical vapor deposition,” J. Appl. Phys. 91(9), 6085–6088 (2002). [CrossRef]

16.

F. Gonella and P. Mazzoldi, “Metal nanocluster composite glasses,” in Handbook of Nanostructured Materials and Nanotechnology, Nalwa HS (Ed), vol 4. (Academic, 2000).

17.

T. Som and B. Karmakar, “Core shell Au Ag Nanoparticles in Dielectric Nanocomposites with Plasmon-Enhanced Fluorescence: A New Paradigm in Antimony Glasses,” Nano Res. 2(8), 607–616 (2009). [CrossRef]

18.

T. Som and B. Karmakar, “Surface Plasmon Resonance and Enhanced Fluorescence Application of Single-Step Synthesized Elliptical Nano Gold-embedded Antimony Glass Dichroic Nanocomposites,” Plasmonics 5(2), 149–159 (2010). [CrossRef]

19.

T. Sekiya, N. Mochida, A. Ohtsuka, and A. Soejima, “Raman spectra of BO3/2-TeO2 glasses,” J. Non-Cryst. Solids 151(3), 222–228 (1992). [CrossRef]

20.

T. Komatsu, H. Tawarayama, H. Mohri, and K. Matusita, “Properties and crystallization behaviors of TeO2-LiNbO3 glasses,” J. Non-Cryst. Solids 135(2-3), 105–113 (1991). [CrossRef]

21.

K. A. Alim, V. A. Fonoberov, M. Shamsa, and A. A. Balandin, “Micro-Raman investigation of optical phonons in ZnO nanocrystals,” J. Appl. Phys. 97(12), 124313 (2005). [CrossRef]

22.

M. Fleischmann, P. J. Hendra, and A. J. McQuillan, “Raman spectra of pyridine adsorbed at a silver electrode,” Chem. Phys. Lett. 26(2), 163–166 (1974). [CrossRef]

23.

E. Nardou, D. Vouagner, A.-M. Jurdyc, A. Berthelot, A. Pillonnet, V. Sablonière, F. Bessueille, and B. Champagnon, “Surface enhanced Raman scattering in an amorphous matrix for Raman amplification,” J. Non-Cryst. Solids 357(8-9), 1895–1899 (2011). [CrossRef]

24.

K. Kneipp, “Surface-enhanced Raman scattering ,” Phys. Today, 40–46 (2007).

25.

M. K. Hossain and Y. Ozaki, “Surface-enhanced Raman scattering: facts and inline trends,” Curr. Sci. 97, 192–201 (2009).

26.

A. M. Michaels, M. Nirmal, and L. E. Brus, “Surface enhanced Raman spectroscopy of individual rhodamine 6G molecules on large Ag nanocrystals,” J. Am. Chem. Soc. 121(43), 9932–9939 (1999). [CrossRef]

27.

P. Etchegoin, H. Liem, R. C. Maher, L. F. Cohen, R. J. C. Brown, H. Hartigan, M. J. T. Milton, and J. C. Gallop, “A novel amplification mechanism for surface enhanced Raman scattering,” Chem. Phys. Lett. 366(1-2), 115–121 (2002). [CrossRef]

28.

A. Otto, I. Mrozek, H. Grabhorn, and W. Akemann, “Surface-enhanced Raman scattering,” Condens. Matter. 4(5), 1143–1212 (1992). [CrossRef]

29.

S. Nie and S. R. Emory, “Probing single molecules and single nanoparticles by surface-enhanced Raman scattering,” Science 275(5303), 1102–1106 (1997). [CrossRef] [PubMed]

30.

R. J. Amjad, M. R. Sahar, S. K. Ghoshal, M. R. Dousti, S. Riaz, A. R. Samavati, R. Arifin, and S. Naseem, “Annealing time dependent up-conversion luminescence enhancement in magnesium–tellurite glass,” J. Lumin. 136, 145–149 (2013). [CrossRef]

31.

R. J. Amjad, M. R. Sahar, S. K. Ghoshal, M. R. Dousti, S. Riaz, and B. A. Tahir, “Enhanced infrared to visible upconversion emission in Er3+ doped phosphate glass: Role of silver nanoparticle,” J. Lumin. 132(10), 2714–2718 (2012). [CrossRef]

32.

L. R. P. Kassab, C. B. de Araújo, R. A. Kobayashi, R. D. De, A. Pinto, and D. M. da Silva, “Influence of silver nanoparticles in the luminescence efficiency of Pr3+-doped tellurite glasses,” J. Appl. Phys. 102, 103515 (2007).

33.

L. R. P. Kassab, F. A. Bomfim, J. R. Martinelli, N. U. Wetter, J. J. Neto, and C. B. de Araújo, “Energy transfer and frequency upconversion in Yb3+–Er3+-doped PbO- GeO2 glass containing silver nanoparticles,” Appl. Phys. B 94(2), 239–242 (2009). [CrossRef]

34.

F. Le, D. W. Brandl, Y. A. Urzhumov, H. Wang, J. Kundu, N. J. Halas, J. Aizpurua, and P. Nordlander, “Metallic Nanoparticle Arrays: A common substrate for both surface-enhanced Raman scattering and surface-enhanced infrared absorption,” ACS Nano 2(4), 707–718 (2008). [CrossRef] [PubMed]

35.

O. L. Malta and M. A. dos Santos, “Theoretical analysis of the fluorescence yield of rare earth ions in glasses containing small metallic particles,” Chem. Phys. Lett. 174(1), 13–18 (1990). [CrossRef]

36.

T. Hayakawa, S. T. Selvan, and M. Nogami, “Field enhancement effect of small Ag particles on the fluorescence from Eu3+-doped SiO2 glass,” Appl. Phys. Lett. 74(11), 1513–1515 (1999). [CrossRef]

37.

C. D. Geddes, I. Gryczynski, J. Malicka, Z. Gryczynski, and J. R. Lakowicz, “Metal-enhanced fluorescence: Potential applications in HTS,” Comb. Chem. High Throughput Screen. 6(2), 109–117 (2003). [CrossRef] [PubMed]

38.

J. Zhu, “SPR induced quenching of the 5D17F1 emission of Eu3+ doped gold colloids,” Phys. Lett. A 341(1-4), 212–215 (2005). [CrossRef]

39.

E. G. Matveeva, T. Shtoyko, I. Gryczynski, I. Akopova, and Z. Gryczynski, “Fluorescence quenching/enhancement surface assays: Signal manipulation using silver-coated gold nanoparticles,” Chem. Phys. Lett. 454(1-3), 85–90 (2008). [CrossRef] [PubMed]

40.

T. Som and B. Karmakar, “Nanosilver enhanced upconversion fluorescence of erbium ions in Er3+: Ag-antimony glass nanocomposites,” J. Appl. Phys. 105(1), 013102 (2009). [CrossRef]

41.

V. A. G. Rivera, S. P. A. Osorio, Y. Ledemi, D. Manzani, Y. Messaddeq, L. A. O. Nunes, and E. Marega Jr., “Localized surface plasmon resonance interaction with Er3+-doped tellurite glass,” Opt. Express 18(24), 25321–25328 (2010). [CrossRef] [PubMed]

OCIS Codes
(060.4510) Fiber optics and optical communications : Optical communications
(240.6680) Optics at surfaces : Surface plasmons
(300.6280) Spectroscopy : Spectroscopy, fluorescence and luminescence

ToC Category:
Optics at Surfaces

History
Original Manuscript: February 15, 2013
Revised Manuscript: April 4, 2013
Manuscript Accepted: April 16, 2013
Published: June 7, 2013

Citation
Raja J. Amjad, M. R. Sahar, M. R. Dousti, S. K. Ghoshal, and M. N. A. Jamaludin, "Surface enhanced Raman scattering and plasmon enhanced fluorescence in zinc-tellurite glass," Opt. Express 21, 14282-14290 (2013)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-12-14282


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References

  1. M. Fujii, M. Yoshida, Y. Kanzawa, S. Hayashi, and K. Yamamoto, “1.54 μm photoluminescence of Er3+ doped into SiO2 films containing Si nanocrystals: Evidence for energy transfer from Si nanocrystals to Er3+,” Appl. Phys. Lett.71(9), 1198–1200 (1997). [CrossRef]
  2. S. Moon, P. R. Watekar, B. H. Kim, and W. T. Han, “Fabrication and photoluminescence characteristics of Er3+-doped optical fibre sensitised by silicon,” Electron. Lett.43(2), 85–87 (2007). [CrossRef]
  3. S. Ju, V. L. Nguyen, P. R. Watekar, B. H. Kim, C. Jeong, S. Boo, C. J. Kim, and W. T. Han, “Fabrication and optical characteristics of a novel optical fiber doped with the Au nanoparticles,” J. Nanosci. Nanotechnol.6(11), 3555–3558 (2006). [CrossRef] [PubMed]
  4. M. P. Hehlen, N. J. Cockroft, T. R. Gosnell, and A. J. Bruce, “Spectroscopic properties of Er3+ and Yb3+doped soda-lime silicate and aluminosilicate glasses,” Phys. Rev. B56(15), 9302–9318 (1997). [CrossRef]
  5. C. Strohhofer and A. Polman, “Silver as a sensitizer for erbium,” Appl. Phys. Lett.81(8), 1414–1416 (2002). [CrossRef]
  6. S. A. Maier and H. A. Atwater, “Plasmonics: Localization and guiding of electromagnetic energy in metal/dielectric structures,” J. Appl. Phys.98(1), 011101 (2005). [CrossRef]
  7. W. L. Barnes, A. Dereux, and T. W. Ebbesen, “Surface plasmon subwavelength optics,” Nature424(6950), 824–830 (2003). [CrossRef] [PubMed]
  8. C. D. Geddes and J. R. Lakowicz, “Editorial: Metal-enhanced fluorescence,” J. Fluoresc.12(2), 121–129 (2002). [CrossRef] [PubMed]
  9. K. Aslan, I. Gryczynski, J. Malicka, E. Matveeva, J. R. Lakowicz, and C. D. Geddes, “Metal-enhanced fluorescence: an emerging tool in biotechnology,” Curr. Opin. Biotechnol.16(1), 55–62 (2005). [CrossRef] [PubMed]
  10. A. V. Zayats, I. I. Smolyaninov, and A. A. Maradudin, “Nano-optics of surface plasmon polaritons,” Phys. Rep.408(3-4), 131–314 (2005). [CrossRef]
  11. J. R. Lakowicz, “Radiative decay engineering: biophysical and biomedical applications,” Anal. Biochem.298(1), 1–24 (2001). [CrossRef] [PubMed]
  12. J. R. Lakowicz, Y. Shen, S. D’Auria, J. Malicka, J. Fang, Z. Gryczynski, and I. Gryczynski, “Radiative decay engineering. 2. Effects of silver island films on fluorescence intensity, lifetimes, and resonance energy transfer,” Anal. Biochem.301(2), 261–277 (2002). [CrossRef] [PubMed]
  13. E. B. Desurvire, “Capacity demand and technology challenges for lightwave systems in the next two decades,” J. Lightwave Technol.24(12), 4697–4710 (2006). [CrossRef]
  14. J. A. García-Macedo, G. Valverde, J. Lockard, and J. I. Zink, “SERS on mesostructured thin films with silver nanoparticles,” Proc. SPIE5361, 117–124 (2004). [CrossRef]
  15. D. Roy, Z. H. Barber, and T. W. Clyne, “Ag nanoparticle induced surface enhanced Raman spectroscopy of chemical vapor deposition diamond thin films prepared by hot filament chemical vapor deposition,” J. Appl. Phys.91(9), 6085–6088 (2002). [CrossRef]
  16. F. Gonella and P. Mazzoldi, “Metal nanocluster composite glasses,” in Handbook of Nanostructured Materials and Nanotechnology, Nalwa HS (Ed), vol 4. (Academic, 2000).
  17. T. Som and B. Karmakar, “Core shell Au Ag Nanoparticles in Dielectric Nanocomposites with Plasmon-Enhanced Fluorescence: A New Paradigm in Antimony Glasses,” Nano Res.2(8), 607–616 (2009). [CrossRef]
  18. T. Som and B. Karmakar, “Surface Plasmon Resonance and Enhanced Fluorescence Application of Single-Step Synthesized Elliptical Nano Gold-embedded Antimony Glass Dichroic Nanocomposites,” Plasmonics5(2), 149–159 (2010). [CrossRef]
  19. T. Sekiya, N. Mochida, A. Ohtsuka, and A. Soejima, “Raman spectra of BO3/2-TeO2 glasses,” J. Non-Cryst. Solids151(3), 222–228 (1992). [CrossRef]
  20. T. Komatsu, H. Tawarayama, H. Mohri, and K. Matusita, “Properties and crystallization behaviors of TeO2-LiNbO3 glasses,” J. Non-Cryst. Solids135(2-3), 105–113 (1991). [CrossRef]
  21. K. A. Alim, V. A. Fonoberov, M. Shamsa, and A. A. Balandin, “Micro-Raman investigation of optical phonons in ZnO nanocrystals,” J. Appl. Phys.97(12), 124313 (2005). [CrossRef]
  22. M. Fleischmann, P. J. Hendra, and A. J. McQuillan, “Raman spectra of pyridine adsorbed at a silver electrode,” Chem. Phys. Lett.26(2), 163–166 (1974). [CrossRef]
  23. E. Nardou, D. Vouagner, A.-M. Jurdyc, A. Berthelot, A. Pillonnet, V. Sablonière, F. Bessueille, and B. Champagnon, “Surface enhanced Raman scattering in an amorphous matrix for Raman amplification,” J. Non-Cryst. Solids357(8-9), 1895–1899 (2011). [CrossRef]
  24. K. Kneipp, “Surface-enhanced Raman scattering,” Phys. Today, 40–46 (2007).
  25. M. K. Hossain and Y. Ozaki, “Surface-enhanced Raman scattering: facts and inline trends,” Curr. Sci.97, 192–201 (2009).
  26. A. M. Michaels, M. Nirmal, and L. E. Brus, “Surface enhanced Raman spectroscopy of individual rhodamine 6G molecules on large Ag nanocrystals,” J. Am. Chem. Soc.121(43), 9932–9939 (1999). [CrossRef]
  27. P. Etchegoin, H. Liem, R. C. Maher, L. F. Cohen, R. J. C. Brown, H. Hartigan, M. J. T. Milton, and J. C. Gallop, “A novel amplification mechanism for surface enhanced Raman scattering,” Chem. Phys. Lett.366(1-2), 115–121 (2002). [CrossRef]
  28. A. Otto, I. Mrozek, H. Grabhorn, and W. Akemann, “Surface-enhanced Raman scattering,” Condens. Matter.4(5), 1143–1212 (1992). [CrossRef]
  29. S. Nie and S. R. Emory, “Probing single molecules and single nanoparticles by surface-enhanced Raman scattering,” Science275(5303), 1102–1106 (1997). [CrossRef] [PubMed]
  30. R. J. Amjad, M. R. Sahar, S. K. Ghoshal, M. R. Dousti, S. Riaz, A. R. Samavati, R. Arifin, and S. Naseem, “Annealing time dependent up-conversion luminescence enhancement in magnesium–tellurite glass,” J. Lumin.136, 145–149 (2013). [CrossRef]
  31. R. J. Amjad, M. R. Sahar, S. K. Ghoshal, M. R. Dousti, S. Riaz, and B. A. Tahir, “Enhanced infrared to visible upconversion emission in Er3+ doped phosphate glass: Role of silver nanoparticle,” J. Lumin.132(10), 2714–2718 (2012). [CrossRef]
  32. L. R. P. Kassab, C. B. de Araújo, R. A. Kobayashi, R. D. De, A. Pinto, and D. M. da Silva, “Influence of silver nanoparticles in the luminescence efficiency of Pr3+-doped tellurite glasses,” J. Appl. Phys.102, 103515 (2007).
  33. L. R. P. Kassab, F. A. Bomfim, J. R. Martinelli, N. U. Wetter, J. J. Neto, and C. B. de Araújo, “Energy transfer and frequency upconversion in Yb3+–Er3+-doped PbO- GeO2 glass containing silver nanoparticles,” Appl. Phys. B94(2), 239–242 (2009). [CrossRef]
  34. F. Le, D. W. Brandl, Y. A. Urzhumov, H. Wang, J. Kundu, N. J. Halas, J. Aizpurua, and P. Nordlander, “Metallic Nanoparticle Arrays: A common substrate for both surface-enhanced Raman scattering and surface-enhanced infrared absorption,” ACS Nano2(4), 707–718 (2008). [CrossRef] [PubMed]
  35. O. L. Malta and M. A. dos Santos, “Theoretical analysis of the fluorescence yield of rare earth ions in glasses containing small metallic particles,” Chem. Phys. Lett.174(1), 13–18 (1990). [CrossRef]
  36. T. Hayakawa, S. T. Selvan, and M. Nogami, “Field enhancement effect of small Ag particles on the fluorescence from Eu3+-doped SiO2 glass,” Appl. Phys. Lett.74(11), 1513–1515 (1999). [CrossRef]
  37. C. D. Geddes, I. Gryczynski, J. Malicka, Z. Gryczynski, and J. R. Lakowicz, “Metal-enhanced fluorescence: Potential applications in HTS,” Comb. Chem. High Throughput Screen.6(2), 109–117 (2003). [CrossRef] [PubMed]
  38. J. Zhu, “SPR induced quenching of the 5D1→7F1 emission of Eu3+ doped gold colloids,” Phys. Lett. A341(1-4), 212–215 (2005). [CrossRef]
  39. E. G. Matveeva, T. Shtoyko, I. Gryczynski, I. Akopova, and Z. Gryczynski, “Fluorescence quenching/enhancement surface assays: Signal manipulation using silver-coated gold nanoparticles,” Chem. Phys. Lett.454(1-3), 85–90 (2008). [CrossRef] [PubMed]
  40. T. Som and B. Karmakar, “Nanosilver enhanced upconversion fluorescence of erbium ions in Er3+: Ag-antimony glass nanocomposites,” J. Appl. Phys.105(1), 013102 (2009). [CrossRef]
  41. V. A. G. Rivera, S. P. A. Osorio, Y. Ledemi, D. Manzani, Y. Messaddeq, L. A. O. Nunes, and E. Marega., “Localized surface plasmon resonance interaction with Er3+-doped tellurite glass,” Opt. Express18(24), 25321–25328 (2010). [CrossRef] [PubMed]

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