Optical properties and ultrafast electron dynamics in gold–silver alloy and core–shell nanoparticles

Hubenthal, Frank; Borg, N.; Träger, F.

doi:10.1007/s00340-008-3146-8

Cited by 43 publications

(25 citation statements)

References 51 publications

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“…After preparation, the nanoparticle ensemble has been characterized by atomic force microscopy (AFM) and optical spectroscopy. Details of the preparation procedure and the nanoparticle characterization are presented elsewhere [20,22]. The nanoparticle ensemble used in the presented experiments was prepared with a SPR position at 491 nm, which corresponds to an axial ratio of a/b ≈ 0.22.…”

Section: Methodsmentioning

confidence: 99%

Naturally grown Ag nanoparticles on quartz substrates as SERS substrate excited by a 488 nm diode laser system for SERDS

et al. 2012

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A silver nanoparticle ensemble was prepared under ultrahigh vacuum (UHV) conditions by Volmer-Weber growth on a quartz substrate for surface-enhanced Raman scattering (SERS) investigations of pyrene molecules. To tune the surface plasmon resonance frequency in the vicinity of the excitation wavelength of 488 nm of the diode laser, the morphology of the silver nanoparticles was optimized. The substrates were mounted in a flow-through cell as part of the optical Raman set-up. A microsystem diode laser generates two slightly different emission wavelengths (λ = 487.61 nm and λ = 487.91 nm) with a spectral width <10 pm and an optical power of 20 mW, i.e. SERS experiments are possible but also shifted excitation Raman difference spectroscopy (SERDS) can be carried out. For trace analysis of pyrene in water we demonstrate SERS/SERDS experiments which lead to a limit of detection of 2 nmol/l for pyrene. These results suggest that with silver nanoparticle ensembles excited at their plasmon resonance at 488 nm combined SERS/SERDS measurements can be effectively performed for in-situ trace analysis of pollutant chemicals in water.

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Section: Methodsmentioning

confidence: 99%

Naturally grown Ag nanoparticles on quartz substrates as SERS substrate excited by a 488 nm diode laser system for SERDS

et al. 2012

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“…However, the importance of experimental determination of optical constants is not discussed [9][10][11] in spite of morphology differences depending on chemical and thermal of sputtering methods of alloying.…”

Section: Optical Constants Of Au-ag and Au-cu Alloysmentioning

confidence: 97%

Engineering gold alloys for plasmonics

et al. 2014

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We demonstrate the formation of metal alloys in Au-Ag, Au-Cu and Au-Pd systems and the experimental determination of their optical properties using optical transmission and reflection spectroscopy. The optical constants define the plasmon resonance wavelength and electromagnetic field local intensity. However, the optical constants behavior cannot be precisely modeled based on the data of pure metals due to unknown morphology and composition of the alloy. It has to be determined experimentally. We demonstrate the surface-enhanced Raman scattering using alloy metals. Depending on the metal to which molecules are adsorbed, we observe enhancement of different Raman modes. It is mainly due to the chemical enhancement effect between metal and molecules

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“…According to Equation (2), for ellipsoidal nanoparticles three plasmon resonances can be excited. Since the plasmon resonance is highly sensitive to the nanoparticle morphology, optical spectroscopy has widely been used as a characterization tool [17][18][19][20][21][22]. While the position of the plasmon resonance is sensitive to the particle morphology and environment, its width is usually a superposition of homogeneous and inhomogeneous broadening.…”

Section: Introductionmentioning

confidence: 99%

Determination of Morphological Parameters of Supported Gold Nanoparticles: Comparison of AFM Combined with Optical Spectroscopy and Theoretical Modeling versus TEM

2012

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The morphology of small gold particles prepared by Volmer-Weber growth on sapphire substrates have been investigated by two different characterization techniques. First, by non-extensive atomic force microscopy (AFM) in combination with optical spectroscopy and modeling of the optical properties using a theoretical model, recently developed in our group. Second, by extensive transmission electron microscopy (TEM). Comparing the results obtained with both techniques demonstrate that for small gold nanoparticles within the quasistatic limit, the morphological properties can be precisely determined by an appropriate theoretical modeling of the optical properties in combination with simple AFM measurements. The apparent mean axial ratio of the nanoparticles, i.e., the axial ratio that corresponds to the center frequency of the ensemble plasmon resonance, is obtained easily from the extinction spectrum. The mean size is determined by the nanoparticle number density and the amount of deposited material, measured by AFM and a quartz micro balance, respectively. To extract the most probable axial ratio of the nanoparticle ensemble, i.e., the axial ratio that corresponds to the most probable nanoparticle size in the ensemble, we apply the new theoretical model, which allows to extract the functional dependence of the nanoparticle shape on its size. The morphological parameters obtained with this procedure will be afterwards compared to extensive TEM measurements. The results obtained with both techniques yield excellent agreement. For example, the lateral dimensions of the nanoparticles after deposition of 15.2 × 10 15 atoms/cm 2 of gold has been compared. While a mean lateral diameter of (13 ± 2) nm has been extracted from AFM, optical spectroscopy and modeling, a value of (12 ± 2) nm is derived from TEM.

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Optical properties and ultrafast electron dynamics in gold–silver alloy and core–shell nanoparticles

Cited by 43 publications

References 51 publications

Naturally grown Ag nanoparticles on quartz substrates as SERS substrate excited by a 488 nm diode laser system for SERDS

Naturally grown Ag nanoparticles on quartz substrates as SERS substrate excited by a 488 nm diode laser system for SERDS

Engineering gold alloys for plasmonics

Determination of Morphological Parameters of Supported Gold Nanoparticles: Comparison of AFM Combined with Optical Spectroscopy and Theoretical Modeling versus TEM

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