OSA's Digital Library

Optical Materials Express

Optical Materials Express

  • Editor: David J. Hagan
  • Vol. 2, Iss. 9 — Sep. 1, 2012
  • pp: 1226–1235
« Show journal navigation

Unusual optical properties of the Au/Ag alloy at the matching mole fraction

Yoshiaki Nishijima and Shunsuke Akiyama  »View Author Affiliations


Optical Materials Express, Vol. 2, Issue 9, pp. 1226-1235 (2012)
http://dx.doi.org/10.1364/OME.2.001226


View Full Text Article

Acrobat PDF (1550 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

Optical properties of localized surface plasmon resonance (LSPR) in Au/Ag alloy were investigated experimentally and numerically. It was found that LSPR spectra of nanostructures at near-infrared wavelengths changed drastically at the 50% Au/Ag mole fraction. Both the experimental results and the finite-difference time-domain simulations using experimentally obtained n, k values showed a similar tendency. At 50% molar fraction, electromagnetic field enhancement reached almost the same value as in pure Au.

© 2012 OSA

1. Introduction

In this study, we systematically investigated the optical properties of the Au/Ag alloy. Optical properties of alloy nanostructures were experimentally determined, and the finite difference time domain (FDTD) simulations were used to compare optical extinction spectra. Au and Ag, which are well known plasmonic materials, can form a homogeneously face-centered-cubic (fcc) structure for any composition ratio of the metals (see the phase diagram in Fig. 1(a)
Fig. 1 Phase diagram of Au/Ag alloy. (a) Melting point values in the phase diagram are obtained from [25] and inset shows a photograph of bulk alloys with Au concentration ranging from 0% (pure Au), 16.7%, 50%, 70% and to 100%. (b) X-ray crystal diffraction spectroscopy of Au, Ag, and Au/Ag alloy (Au:Ag = 1:1).
, [25

25. ASM, ASM Handbook: Volume 3: Alloy Phase Diagrams (ASM International, 1992).

]) since they have similar atomic radii, lattice constants, and electronic structures. Nanoparticles of Au and Ag alloyed with different ratios were fabricated and characterized experimentally; their optical properties were modeled. New properties of the Au-Ag 50% mixture at near-IR wavelengths is explained by electronegativity and chemical bonding, which reduce electron scattering and losses in the near-IR region.

2. Experimental details

Au/Ag alloy nanostructures are fabricated by electron-beam lithography (EBL) and lift-off [26

26. K. Ueno, S. Juodkazis, V. Mizeikis, K. Sasaki, and H. Misawa, “Spectrally-resolved atomic-scale length variations of gold nanorods,” J. Am. Chem. Soc. 128(44), 14226–14227 (2006). [CrossRef] [PubMed]

28

28. Y. Nishijima, L. Rosa, and S. Juodkazis, “Surface plasmon resonances in periodic and random patterns of gold nano-disks for broadband light harvesting,” Opt. Express 20(10), 11466–11477 (2012). [CrossRef] [PubMed]

]. Resist (ZEP520A, Zeon Co.) was spin-coated on to a glass substrate at 3000 rpm for 60 s. After baking at 180°C for 2 min, the surface of the resist was coated with a charge-dissipating agent (ESPACER-300Z, Showa Denko Co. Ltd.) for EBL. Circular patterns were drawn with a 50 kV acceleration voltage using the EBL system (ELS 7500EX, ELIONIX Inc.). After development in ZEP-RD (from Zeon Co.) for 1 min and being rinsed twice with ZMD-B for 15 s, a 2 nm layer of Cr or Ni was deposited as an adhesion layer, followed by a 35 nm layer of the alloy. In both cases, a vacuum evaporation system (VPC-410S, ULVAC Inc.) was used. During the metal deposition, due to the large difference in the boiling points and vapor pressures of Au and Ag, the alloy composition differed from that of bulk evaporation material. Therefore, a multi-step evaporation method was performed to obtain homogeneous alloys. The thickness of the metal evaporated in each process was less than 1 nm, which was determined by a quartz microvalance. (When we deposited a layer with more than 1 nm thickness, the extinction spectra showed unstable behavior) Next, lift-off was performed in the resist remover (ZDMAC, Zeon Co.) at 60°C for 3 min, and the device was then rinsed with acetone and methanol.

The resulting structures were characterized by a scanning electron microscope (SEM; JSM-7500F, JEOL Ltd.) and by energy-dispersive spectroscopy (EDS). The transmission spectrum was measured using a confocal microscope system combined with a standard optical microscope (10 times objective lens, NA = 0.5, the pinhole was 0.1 mm in diameter, Optiphoto2, NIKON Co.) and an optical spectrum analyzer (Q8381A, Advantest Co. Ltd.). The crystal form of alloy films was measured using X-ray crystal diffraction by the 2θ -θ method (RINT2500, Rigaku Co.). The optical constants of the film alloy metals were determined by reflection and transmission measurements. Transmission and reflection spectra for different film thicknesses were fitted by the least-linear-square method according to the Drude model [24

24. E. D. Palik, Handbook of Optical Constants of Solids (Academic Press Handbook Series, 1985).

,29

29. G. Burns, Solid State Physics (Academic Press, 1985).

] in the near-IR spectral range. Determined optical constants were used for the FDTD analysis using commercially available software (FDTD solutions, Lumerical Co. Ltd.) to simulate the extinction spectra and electromagnetic field enhancement.

3. Results and discussions

Figure 1(b) shows the thin film X-ray crystal diffraction measurement result. The fcc crystal structure of Au, Ag, and their alloy was determined by X-ray diffraction (XRD). In the case of the fcc crystal structures, XRD peaks appear at angles where all (hkl) values become even or odd. Here, for the 2θ span from 30° to 90°, we see 5 peaks characteristic of the (111), (200), (222), (311), and (222) planes. The atomic radii of Au and Ag are both 144 pm, while the lattice constants are 4.0788 and 4.0862 Å, respectively. Because of these similar crystal parameters, the diffraction peak position appears at similar angles. For the (111) orientation of the crystal, Au/Ag alloy peaks were linearly shifted by a slight amount with respect to the alloy composition, in accordance with Vegard's law [30

30. A. R. Denton and N. W. Ashcroft, “Vegard’s law,” Phys. Rev. A 43(6), 3161–3164 (1991). [CrossRef] [PubMed]

].

Figure 2
Fig. 2 (a) SEM image of Au/Ag alloy and (d) EDS mapping of Au and Ag in pure Au, Ag, and 50% alloy.
shows scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) images of the Au and Ag alloy nanostructures. From the EDS imaging result, the Au (peaks at 2.17 eV, M-shell) and Ag (peaks at 3.06 eV, L-shell) counts were collected. The results showed that nanostructures homogeneously include both Au and Ag within the EDS spatial resolution.

Figure 3
Fig. 3 Extinction spectra of the Au/Ag alloy with various compositions and for 250 (a) and 350 nm (b) diameter nanodisc patterns; period is 450 nm, thickness of metal 35 nm.
shows the extinction spectra of pattern of nanodiscs of the Au/Ag alloy. By keeping the size and periodicity of nanostructures the same for all compositions, nanodisc alloy was fabricated with seven different compositions and the corresponding extinction spectra were measured. Both 250 and 350 nm nanodiscs show similar behavior, and the spectrum is governed by a blue-shift as the Au mole fraction decreases from 100% to 75% and a red-shift at exactly 50% value; a blue-shift again governs the spectrum for a larger proportion of Ag (i.e., towards 100% Ag). This tendency was independent of the nanodisc diameter, as shown in Fig. 3(b). The spectral shift of the 250 nm nanodisc pattern was larger than that of the 350 nm nanodisc. This was due to a small change in the permittivity in this wavelength range. In addition, when we deposited a layer with more than 1 nm thickness, spectral behavior changed significantly. For example, the 50% spectrum was blue shifted by the largest extent. However, through annealing at 100°C, extinction spectrum easily shifted to longer wavelengths, similar to the case of the deposited layer with <1 nm thickness. Although this phenomenon required further investigation, during annealing treatment, the atom moved into a stable arrangement, and deposition with <1 nm layer thickness could be concluded to lead to well-mixed alloy formation.

In order to verify scattering results from the patterns of nanoparticles, experimental values of n, k were determined. Films were prepared with three controlled-thickness deposition values of 20, 30, 40 nm, and the transmission and reflection spectra were measured from 300 nm to 1600 nm for these films. From these spectral data, n, k, d were determined.

Figure 4
Fig. 4 The refractive index, n and k, of pure Au, Ag, and 50% Au/Ag alloy determined experimentally and the arithmetic average of pure Au and Ag reference data.
shows the experimentally determined n, k values of pure Au and Ag as well as the 50% Au/Ag alloy. The n, k values of arithmetical average of Au and Ag is also shown. The values for Au and Ag were obtained from the available literature. (In addition, we have checked that using our experimental setup, we obtain the same n, k values for the Au film as in the literature.) From UV to visible wavelengths, the experimentally obtained n, k values for the Au/Ag alloy were similar to those obtained by the averaging method. Optical properties in this wavelength range were caused by inter-band transition. The band-edge wavelength (a sharp transition feature) shifted continuously between Au and Ag according to their composition, and this agrees with previously reported results [9

9. Y. Herbani, T. Nakamura, and S. Sato, “Synthesis of near-monodispersed Au and Ag nanoalloys by high intensity laser irradiation of metal ions in hexane,” J. Phys. Chem. C 115(44), 21592–21598 (2011). [CrossRef]

20

20. R. Kuladeep, L. Jyothi, K. S. Alee, K. L. N. Deepak, and D. N. Rao, “Laser-assisted synthesis of Au-Ag alloy nanoparticles with tunable surface plasmon resonance frequency,” Opt. Mater. Express 2(2), 161–172 (2012). [CrossRef]

]. However, at wavelengths longer than 700 nm in the near-IR region, this behavior changed dramatically. In the experimental results, increase in the n and decrease in the k values, as compared to those of pure Au and Ag, were observed. To get further insights into these experimental results, FDTD simulations were performed using the experimentally determined n, k values. Simulations were performed with the following parameters: 250 nm nanodisc diameter, 35 nm thickness of metal (or alloy), and 450 nm periodicity of the pattern. The structure was excited by a plane- wave from the backside of the glass substrate, and the transmission monitor was positioned 15 nm above the nanodisc surface. Intensity monitors were positioned at the middle of the nanodiscs to observe the enhanced light intensity at the LSPR peak.

Figure 5
Fig. 5 FDTD analysis of Au/Ag alloy with experimentally obtained (solid line) and arithmetical average of gold and silver (dashed line) n, k values: (a) extinction spectra, (b) electromagnetic field enhancement; the inset shows the field mapping of gold at peak wavelength of LSPR.
shows the extinction spectra and field enhancement obtained by FDTD simulations. The extinction spectra behavior from the FDTD simulations matched the experimental result almost perfectly. The experimentally obtained n, k values were compared with the arithmetic average of the Au/Ag alloy (shown as a dotted line in Fig. 5(a)). The results predict a blue-shift for a mole fraction change from Au to Ag. The experimentally observed spectroscopic properties of nanodiscs at near-IR wavelengths, where inter band transitions are negligible, can be explained by the optical properties of the alloy (determined by a separate thin-film measurement). To the best of our knowledge, this is the first observation of such behavior. In addition, electromagnetic field enhancement at the resonance peak was calculated and a strong field enhancement was observed at the edge of the nanodisc for a linearly polarized incident plane wave. Figure 5(b) shows a plot of the maximum intensity in the field enhancement map, which is shown in the inset of Fig. 5(b). For all alloy compositions, the enhancement factor was smaller than the arithmetic average, although at 50% Au composition, it was close to the value observed for pure Au.

To understand this characteristic behavior of the 50% Au/Ag alloy, n, k values are analyzed by the Drude model:
ε(ω)=ε1+iε2=εωp2ω2+Γ2+iωp2Γω(ω2+Γ2)
(1)
where ε is the value of ε1 at a high (infinite) frequency, ωp is the bulk plasma frequency defined as (Ne20m)1/2, and Γ = vf /l = 1 /τ is the collision frequency with τ being the relaxation constant; N is the density of free electrons, e is the electron charge, m is the effective mass of electron, vf is the Fermi velocity, which is 1.4 × 106 ms−1 in Au and Ag, and l is the mean free pass of electrons. The electronic conductivity σ0 = ωp2τ was determined. Intra-band absorption of Au and Ag determines the spectral properties of the alloy for wavelengths from UV to 500 nm, and therefore, we consider the wavelength region from 600 to 1600 nm, where inter-band transition is negligible and the Drude equation matches the experimental data well.

For understanding the complicated spectroscopic behaviors seen in Figs. 4 and 5, further FDTD calculations were carried out. Extinction spectra of LSPR can be described by the Mie scattering theory [35

35. S. W. Hsu, K. On, and A. R. Tao, “Localized surface plasmon resonances of anisotropic semiconductor nanocrystals,” J. Am. Chem. Soc. 133(47), 19072–19075 (2011). [CrossRef] [PubMed]

,36

36. C. F. Bohren and D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, 1998).

] and are defined by the permittivity of metals, surrounding media, and volume of nanostructures. For simulations, the permittivity of the metal was defined by the values of ωp and τ; for Au, ωp = 13.8 × 1015 s−1 and τ = 9.3 × 10−15 s. Results of the simulations are shown in Figs. 7(a)
Fig. 7 (a) The ε1 and ε2 dependence on the ωp with fixed τ ( = 9.3 × 10−15 s) and ωp = 12.0 ~15.5 × 1015 s−1; (b) with fixed ωp ( = 13.8 × 1015 s−1) and τ = 5.56 ~50.0 × 10−15 s. (c) Extinction spectra obtained by FDTD calculations with permittivity values modeled in (a) and (b).
and 7(b). When ωp varied at a fixed value of τ, the values of ε1 were significantly reduced for an increasing ωp. At the same time, ε2 slightly increased and was less sensitive to ωp. If τ is altered for a fixed value of ωp, ε1 remains almost constant and ε2 decreases. Using these parameters, the extinction spectra of LSPR, with the same geometry as shown in Fig. 5, were calculated (Fig. 7(c)). An increase in ωp causes a blue-shift of the extinction spectra; however, τ and ε2 are less affected by the spectral shift. The spectral shift also affects the light field enhancement. The calculations show that ωp (or ε1) is a dominant parameter for the experimentally observed LSPR spectral shift shown in Figs. 4 and 5.

4. Conclusion

Systematic investigation of the optical constants of the Au/Ag alloy and optical properties of alloy nanostructures was carried out. Optical constants of the Au/Ag alloy differ from the arithmetic average of the refractive indices of Au and Ag, especially in near-IR wavelength region. In contrast to the case of typical alloy formation, when electronic conductivity and relaxation time are reduced by the addition of impurities and electron scattering, which also result in a reduction of light field enhancement, an unexpected and opposite behavior is observed at near-IR wavelengths with 50% mole fraction. It was found that at a 50% Au/Ag mole fraction, scattering is reduced (and light enhancement is increased) at near-IR wavelengths. This is confirmed by experiments and numerical simulations, using experimentally determined optical constants. It was found that ωp strongly affects the LSPR spectra. This can be explained by the electronegativity difference and chemical bond formation of the metals. Metals with extremely different electronegativity values would result in a decrease in the value of ωp. Therefore, such metal alloy is expected to have large wavelength tunability. Electromagnetic field enhancement is very sensitive to the ordering of the crystal. Atomic radii, bond lengths, and crystal morphology can all be contributing factors to the scattering of electrons.

Chemical stability of alloy nanostructures is a promising feature for practical applications. Silver nanostructures are easily oxidized or sulfurized in an atmospheric environment; Ag nanorod structures break after two months of exposure to the atmosphere [37

37. L. Wang, W. Xiong, Y. Nishijima, Y. Yokota, K. Ueno, H. Misawa, G. Bi, and J. R. Qiu, “Spectral properties and mechanism of instability of nanoengineered silver blocks,” Opt. Express 19(11), 10640–10646 (2011). [CrossRef] [PubMed]

,38

38. M. Mcmahon, R. Lopez, H. Meyer III, L. Feldman, and R. Haglund Jr., “Rapid tarnishing of silver nanoparticles in ambient laboratory air,” Appl. Phys. B 80(7), 915–921 (2005). [CrossRef]

]. Alloying with Au drastically increases its stability, where more than 25% of Au concentration prevents oxidation at 100°C for 1 h. Further studies on alloying at the nanoscale level are required to obtain a better understanding of crystallography. The obtained results are helpful in new material design and in the control of plasmon resonance and chemical stability.

Acknowledgments

The authors thank Otsuka Electronics Co., Ltd. for measurements of the alloy optical constants. The authors also thank Prof. T. Baba (Yokohama National University) for the fruitful discussions and supporting facilities. Y. N. thanks Prof. S. Juodkazis (Swinburne University of Technology) for the fruitful discussions, Profs. H. Misawa and K. Ueno (Hokkaido Univ.) for the initial explanation of the fabrication methods. This work was financially supported by the Ministry of Education, Culture, Sports, Science, and Technology: KAKENHI Grant-in-Aid for scientific research, the Yokohama Academic Foundation, and the Research Foundation for Optical Science and Technology, Hamamatsu, Japan.

References and links

1.

A. Pipino and V. Silin, “Gold nanoparticle response to nitro-compounds probed by cavity ring-down spectroscopy,” Chem. Phys. Lett. 404(4-6), 361–364 (2005). [CrossRef]

2.

F. Lordan, J. H. Rice, B. Jose, R. J. Forster, and T. E. Keyes, “Site selective surface enhanced Raman on nanostructured cavities,” Appl. Phys. Lett. 99(3), 033104 (2011). [CrossRef]

3.

Y. Sawai, B. Takimoto, H. Nabika, K. Ajito, and K. Murakoshi, “Observation of a small number of molecules at a metal nanogap arrayed on a solid surface using surface-enhanced Raman scattering,” J. Am. Chem. Soc. 129(6), 1658–1662 (2007). [CrossRef] [PubMed]

4.

Y. Tsuboi, R. Shimizu, T. Shoji, and N. Kitamura, “Near-infrared continuous-wave light driving a two-photon photochromic reaction with the assistance of localized surface plasmon,” J. Am. Chem. Soc. 131(35), 12623–12627 (2009). [CrossRef] [PubMed]

5.

Y. Nishijima, K. Ueno, Y. Yokota, K. Murakoshi, and H. Misawa, “Plasmon-assisted photocurrent generation from visible to near-infrared wavelength using a Au-nanorods/TiO2 electrode,” J. Phys. Chem. Lett. 1(13), 2031–2036 (2010). [CrossRef]

6.

M. Harada, K. Asakura, Y. Ueki, and N. Toshima, “Structure of polymer-protected palladium-platinum bimetallic clusters at the oxidized state: extended x-ray absorption fine structure analysis,” J. Phys. Chem. 96(24), 9730–9738 (1992). [CrossRef]

7.

N. Toshima, M. Harada, Y. Yamazaki, and K. Asakura, “Catalytic activity and structural analysis of polymer-protected gold-palladium bimetallic clusters prepared by the simultaneous reduction of hydrogen tetrachloroaurate and palladium dichloride,” J. Phys. Chem. 96(24), 9927–9933 (1992). [CrossRef]

8.

K. Kusada, M. Yamauchi, H. Kobayashi, H. Kitagawa, and Y. Kubota, “Hydrogen-storage properties of solid-solution alloys of immiscible neighboring elements with Pd,” J. Am. Chem. Soc. 132(45), 15896–15898 (2010). [CrossRef] [PubMed]

9.

Y. Herbani, T. Nakamura, and S. Sato, “Synthesis of near-monodispersed Au and Ag nanoalloys by high intensity laser irradiation of metal ions in hexane,” J. Phys. Chem. C 115(44), 21592–21598 (2011). [CrossRef]

10.

Y. Herbani, T. Nakamura, and S. Sato, “Femtosecond laser -induced formation of Au-rich nanoalloys from the aqueous mixture of Au-Ag ions,” J. Nanomater. 2010, 154210 (2010). [CrossRef]

11.

S. Link, Z. L. Wang, and M. A. El-Sayed, “Alloy formation of gold and silver nanoparticles and the dependence of the plasmon absorption on their composition,” J. Phys. Chem. B 103(18), 3529–3533 (1999). [CrossRef]

12.

K. S. Lee and M. A. El-Sayed, “Gold and silver nanoparticles in sensing and imaging: sensitivity of plasmon response to size, shape, and metal composition,” J. Phys. Chem. B 110(39), 19220–19225 (2006). [CrossRef] [PubMed]

13.

N. E. Motl, E. Ewusi-Annan, I. T. Sines, L. Jensen, and R. E. Schaak, “Au and Cu alloy nanoparticles with tunable compositions and plasmonic properties: experimental determination of composition and correlation with theory,” J. Phys. Chem. C 114(45), 19263–19269 (2010). [CrossRef]

14.

F. Hubenthal, N. Borg, and F. Trager, “Optical properties and ultrafast electron dynamics in gold and silver alloy and core and shell nanoparticles,” Appl. Phys. B 93(1), 39–45 (2008). [CrossRef]

15.

S. Link, C. Burda, M. B. Mohamed, B. Nikoobakht, and M. A. El-Sayed, “Laser photothermal melting and fragmentation of gold nanorods: energy and laser pulse-width dependence,” J. Phys. Chem. A 103(9), 1165–1170 (1999). [CrossRef]

16.

P. Mulvaney, M. Giersig, and A. Henglein, “Electrochemistry of multilayer colloids: preparation and absorption spectrum of gold-coated silver particles,” J. Phys. Chem. 97(27), 7061–7064 (1993). [CrossRef]

17.

S. Liu, G. Chen, P. N. Prasad, and M. T. Swihart, “Synthesis of monodisperse Au, Ag, and Au and Ag alloy nanoparticles with tunable size and surface plasmon resonance Frequency,” Chem. Mater. 23, 4098–4101 (2011).

18.

M. Valodkar, S. Modi, A. Pal, and S. Thakore, “Synthesis and anti-bacterial activity of Cu, Ag and Cu and Ag alloy nanoparticles: A green approach,” Mater. Res. Bull. 46(3), 384–389 (2011). [CrossRef]

19.

Z. S. Zhang, Z. J. Yang, X. L. Liu, M. Li, and L. Zhou, “Multiple plasmon resonances of Au/Ag alloyed hollow nanoshells,” Scr. Mater. 63(12), 1193–1196 (2010). [CrossRef]

20.

R. Kuladeep, L. Jyothi, K. S. Alee, K. L. N. Deepak, and D. N. Rao, “Laser-assisted synthesis of Au-Ag alloy nanoparticles with tunable surface plasmon resonance frequency,” Opt. Mater. Express 2(2), 161–172 (2012). [CrossRef]

21.

P. B. Johnson and R. W. Christy, “Optical constants of copper and nickel as a function of temperature,” Phys. Rev. B 11(4), 1315–1323 (1975). [CrossRef]

22.

P. B. Johnson and R. W. Christy, “Optical constants of the noble metals,” Phys. Rev. B 6(12), 4370–4379 (1972). [CrossRef]

23.

P. B. Johnson and R. W. Christy, “Optical constants of transition metals: Ti, V, Cr, Mn, Fe, Co, Ni, and Pd,” Phys. Rev. B 9(12), 5056–5070 (1974). [CrossRef]

24.

E. D. Palik, Handbook of Optical Constants of Solids (Academic Press Handbook Series, 1985).

25.

ASM, ASM Handbook: Volume 3: Alloy Phase Diagrams (ASM International, 1992).

26.

K. Ueno, S. Juodkazis, V. Mizeikis, K. Sasaki, and H. Misawa, “Spectrally-resolved atomic-scale length variations of gold nanorods,” J. Am. Chem. Soc. 128(44), 14226–14227 (2006). [CrossRef] [PubMed]

27.

K. Ueno, S. Juodkazis, V. Mizeikis, D. Ohnishi, K. Sasaki, and H. Misawa, “Inhibition of multipolar plasmon excitation in periodic chains of gold nanoblocks,” Opt. Express 15(25), 16527–16539 (2007). [CrossRef] [PubMed]

28.

Y. Nishijima, L. Rosa, and S. Juodkazis, “Surface plasmon resonances in periodic and random patterns of gold nano-disks for broadband light harvesting,” Opt. Express 20(10), 11466–11477 (2012). [CrossRef] [PubMed]

29.

G. Burns, Solid State Physics (Academic Press, 1985).

30.

A. R. Denton and N. W. Ashcroft, “Vegard’s law,” Phys. Rev. A 43(6), 3161–3164 (1991). [CrossRef] [PubMed]

31.

V. Kuckermann, G. Thummes, H. H. Mende, and M. D. Tiwari, “Electrical deviations from Matthiessen's rule in a Ag:Au alloy,” Solid State Commun. 54(8), 749–752 (1985). [CrossRef]

32.

H. L. Engquist and G. Grimvall, “Electrical transport and deviations from Matthiessen's rule in alloys,” Phys. Rev. B 21(6), 2072–2077 (1980). [CrossRef]

33.

L. Pauling, “The nature of the chemical bond. IV. The energy of single bonds and the relative electronegativity of atoms,” J. Am. Chem. Soc. 54(9), 3570–3582 (1932). [CrossRef]

34.

A. L. Allred and E. G. Rochow, “A scale of electronegativity based on electrostatic force,” J. Inorg. Nucl. Chem. 5(4), 264–268 (1958). [CrossRef]

35.

S. W. Hsu, K. On, and A. R. Tao, “Localized surface plasmon resonances of anisotropic semiconductor nanocrystals,” J. Am. Chem. Soc. 133(47), 19072–19075 (2011). [CrossRef] [PubMed]

36.

C. F. Bohren and D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, 1998).

37.

L. Wang, W. Xiong, Y. Nishijima, Y. Yokota, K. Ueno, H. Misawa, G. Bi, and J. R. Qiu, “Spectral properties and mechanism of instability of nanoengineered silver blocks,” Opt. Express 19(11), 10640–10646 (2011). [CrossRef] [PubMed]

38.

M. Mcmahon, R. Lopez, H. Meyer III, L. Feldman, and R. Haglund Jr., “Rapid tarnishing of silver nanoparticles in ambient laboratory air,” Appl. Phys. B 80(7), 915–921 (2005). [CrossRef]

OCIS Codes
(240.6680) Optics at surfaces : Surface plasmons
(160.4236) Materials : Nanomaterials
(220.4241) Optical design and fabrication : Nanostructure fabrication
(250.5403) Optoelectronics : Plasmonics

ToC Category:
Plasmonics

History
Original Manuscript: May 2, 2012
Revised Manuscript: July 6, 2012
Manuscript Accepted: August 8, 2012
Published: August 9, 2012

Citation
Yoshiaki Nishijima and Shunsuke Akiyama, "Unusual optical properties of the Au/Ag alloy at the matching mole fraction," Opt. Mater. Express 2, 1226-1235 (2012)
http://www.opticsinfobase.org/ome/abstract.cfm?URI=ome-2-9-1226


Sort:  Author  |  Year  |  Journal  |  Reset  

References

  1. A. Pipino and V. Silin, “Gold nanoparticle response to nitro-compounds probed by cavity ring-down spectroscopy,” Chem. Phys. Lett.404(4-6), 361–364 (2005). [CrossRef]
  2. F. Lordan, J. H. Rice, B. Jose, R. J. Forster, and T. E. Keyes, “Site selective surface enhanced Raman on nanostructured cavities,” Appl. Phys. Lett.99(3), 033104 (2011). [CrossRef]
  3. Y. Sawai, B. Takimoto, H. Nabika, K. Ajito, and K. Murakoshi, “Observation of a small number of molecules at a metal nanogap arrayed on a solid surface using surface-enhanced Raman scattering,” J. Am. Chem. Soc.129(6), 1658–1662 (2007). [CrossRef] [PubMed]
  4. Y. Tsuboi, R. Shimizu, T. Shoji, and N. Kitamura, “Near-infrared continuous-wave light driving a two-photon photochromic reaction with the assistance of localized surface plasmon,” J. Am. Chem. Soc.131(35), 12623–12627 (2009). [CrossRef] [PubMed]
  5. Y. Nishijima, K. Ueno, Y. Yokota, K. Murakoshi, and H. Misawa, “Plasmon-assisted photocurrent generation from visible to near-infrared wavelength using a Au-nanorods/TiO2 electrode,” J. Phys. Chem. Lett.1(13), 2031–2036 (2010). [CrossRef]
  6. M. Harada, K. Asakura, Y. Ueki, and N. Toshima, “Structure of polymer-protected palladium-platinum bimetallic clusters at the oxidized state: extended x-ray absorption fine structure analysis,” J. Phys. Chem.96(24), 9730–9738 (1992). [CrossRef]
  7. N. Toshima, M. Harada, Y. Yamazaki, and K. Asakura, “Catalytic activity and structural analysis of polymer-protected gold-palladium bimetallic clusters prepared by the simultaneous reduction of hydrogen tetrachloroaurate and palladium dichloride,” J. Phys. Chem.96(24), 9927–9933 (1992). [CrossRef]
  8. K. Kusada, M. Yamauchi, H. Kobayashi, H. Kitagawa, and Y. Kubota, “Hydrogen-storage properties of solid-solution alloys of immiscible neighboring elements with Pd,” J. Am. Chem. Soc.132(45), 15896–15898 (2010). [CrossRef] [PubMed]
  9. Y. Herbani, T. Nakamura, and S. Sato, “Synthesis of near-monodispersed Au and Ag nanoalloys by high intensity laser irradiation of metal ions in hexane,” J. Phys. Chem. C115(44), 21592–21598 (2011). [CrossRef]
  10. Y. Herbani, T. Nakamura, and S. Sato, “Femtosecond laser -induced formation of Au-rich nanoalloys from the aqueous mixture of Au-Ag ions,” J. Nanomater.2010, 154210 (2010). [CrossRef]
  11. S. Link, Z. L. Wang, and M. A. El-Sayed, “Alloy formation of gold and silver nanoparticles and the dependence of the plasmon absorption on their composition,” J. Phys. Chem. B103(18), 3529–3533 (1999). [CrossRef]
  12. K. S. Lee and M. A. El-Sayed, “Gold and silver nanoparticles in sensing and imaging: sensitivity of plasmon response to size, shape, and metal composition,” J. Phys. Chem. B110(39), 19220–19225 (2006). [CrossRef] [PubMed]
  13. N. E. Motl, E. Ewusi-Annan, I. T. Sines, L. Jensen, and R. E. Schaak, “Au and Cu alloy nanoparticles with tunable compositions and plasmonic properties: experimental determination of composition and correlation with theory,” J. Phys. Chem. C114(45), 19263–19269 (2010). [CrossRef]
  14. F. Hubenthal, N. Borg, and F. Trager, “Optical properties and ultrafast electron dynamics in gold and silver alloy and core and shell nanoparticles,” Appl. Phys. B93(1), 39–45 (2008). [CrossRef]
  15. S. Link, C. Burda, M. B. Mohamed, B. Nikoobakht, and M. A. El-Sayed, “Laser photothermal melting and fragmentation of gold nanorods: energy and laser pulse-width dependence,” J. Phys. Chem. A103(9), 1165–1170 (1999). [CrossRef]
  16. P. Mulvaney, M. Giersig, and A. Henglein, “Electrochemistry of multilayer colloids: preparation and absorption spectrum of gold-coated silver particles,” J. Phys. Chem.97(27), 7061–7064 (1993). [CrossRef]
  17. S. Liu, G. Chen, P. N. Prasad, and M. T. Swihart, “Synthesis of monodisperse Au, Ag, and Au and Ag alloy nanoparticles with tunable size and surface plasmon resonance Frequency,” Chem. Mater.23, 4098–4101 (2011).
  18. M. Valodkar, S. Modi, A. Pal, and S. Thakore, “Synthesis and anti-bacterial activity of Cu, Ag and Cu and Ag alloy nanoparticles: A green approach,” Mater. Res. Bull.46(3), 384–389 (2011). [CrossRef]
  19. Z. S. Zhang, Z. J. Yang, X. L. Liu, M. Li, and L. Zhou, “Multiple plasmon resonances of Au/Ag alloyed hollow nanoshells,” Scr. Mater.63(12), 1193–1196 (2010). [CrossRef]
  20. R. Kuladeep, L. Jyothi, K. S. Alee, K. L. N. Deepak, and D. N. Rao, “Laser-assisted synthesis of Au-Ag alloy nanoparticles with tunable surface plasmon resonance frequency,” Opt. Mater. Express2(2), 161–172 (2012). [CrossRef]
  21. P. B. Johnson and R. W. Christy, “Optical constants of copper and nickel as a function of temperature,” Phys. Rev. B11(4), 1315–1323 (1975). [CrossRef]
  22. P. B. Johnson and R. W. Christy, “Optical constants of the noble metals,” Phys. Rev. B6(12), 4370–4379 (1972). [CrossRef]
  23. P. B. Johnson and R. W. Christy, “Optical constants of transition metals: Ti, V, Cr, Mn, Fe, Co, Ni, and Pd,” Phys. Rev. B9(12), 5056–5070 (1974). [CrossRef]
  24. E. D. Palik, Handbook of Optical Constants of Solids (Academic Press Handbook Series, 1985).
  25. ASM, ASM Handbook: Volume 3: Alloy Phase Diagrams (ASM International, 1992).
  26. K. Ueno, S. Juodkazis, V. Mizeikis, K. Sasaki, and H. Misawa, “Spectrally-resolved atomic-scale length variations of gold nanorods,” J. Am. Chem. Soc.128(44), 14226–14227 (2006). [CrossRef] [PubMed]
  27. K. Ueno, S. Juodkazis, V. Mizeikis, D. Ohnishi, K. Sasaki, and H. Misawa, “Inhibition of multipolar plasmon excitation in periodic chains of gold nanoblocks,” Opt. Express15(25), 16527–16539 (2007). [CrossRef] [PubMed]
  28. Y. Nishijima, L. Rosa, and S. Juodkazis, “Surface plasmon resonances in periodic and random patterns of gold nano-disks for broadband light harvesting,” Opt. Express20(10), 11466–11477 (2012). [CrossRef] [PubMed]
  29. G. Burns, Solid State Physics (Academic Press, 1985).
  30. A. R. Denton and N. W. Ashcroft, “Vegard’s law,” Phys. Rev. A43(6), 3161–3164 (1991). [CrossRef] [PubMed]
  31. V. Kuckermann, G. Thummes, H. H. Mende, and M. D. Tiwari, “Electrical deviations from Matthiessen's rule in a Ag:Au alloy,” Solid State Commun.54(8), 749–752 (1985). [CrossRef]
  32. H. L. Engquist and G. Grimvall, “Electrical transport and deviations from Matthiessen's rule in alloys,” Phys. Rev. B21(6), 2072–2077 (1980). [CrossRef]
  33. L. Pauling, “The nature of the chemical bond. IV. The energy of single bonds and the relative electronegativity of atoms,” J. Am. Chem. Soc.54(9), 3570–3582 (1932). [CrossRef]
  34. A. L. Allred and E. G. Rochow, “A scale of electronegativity based on electrostatic force,” J. Inorg. Nucl. Chem.5(4), 264–268 (1958). [CrossRef]
  35. S. W. Hsu, K. On, and A. R. Tao, “Localized surface plasmon resonances of anisotropic semiconductor nanocrystals,” J. Am. Chem. Soc.133(47), 19072–19075 (2011). [CrossRef] [PubMed]
  36. C. F. Bohren and D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, 1998).
  37. L. Wang, W. Xiong, Y. Nishijima, Y. Yokota, K. Ueno, H. Misawa, G. Bi, and J. R. Qiu, “Spectral properties and mechanism of instability of nanoengineered silver blocks,” Opt. Express19(11), 10640–10646 (2011). [CrossRef] [PubMed]
  38. M. Mcmahon, R. Lopez, H. Meyer, L. Feldman, and R. Haglund., “Rapid tarnishing of silver nanoparticles in ambient laboratory air,” Appl. Phys. B80(7), 915–921 (2005). [CrossRef]

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.


« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited