Optical properties of polycrystalline metallic films

Sotelo, Juan C.; Ederth, J.; Niklasson, Gunnar A.

doi:10.1103/physrevb.67.195106

Cited by 25 publications

(21 citation statements)

References 29 publications

(43 reference statements)

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“…For the films containing grains of 45 nm size (the largest ones studied in Ref. [45]) the reflectance at λ ∼ (750 − 800)nm is 0.8% less than the one calculated from the tabulated data (notice that for smaller grains the difference of the reflectance obtained from the tabulated data is greater). Taking into account that the reflectance in the region of the infrared optics is given by [46] …”

Section: Experimental Precision In the Casimir Force Measure-mentmentioning

confidence: 92%

“…According to Ref. [45], the largest deviations of the reflectance from the one given by the tabulated data [40], takes place at shorter wavelengths. The shortest separation of z = 62 nm in the experiment [11] corresponds to the characteristic wavelength λ c = 2πc/ω c = 4πz ≈ 780 nm.…”

Section: Experimental Precision In the Casimir Force Measure-mentmentioning

confidence: 99%

“…[45] are used where the reflectance R of Au films is measured as a function of the characteristic sizes of the grains.…”

Section: Experimental Precision In the Casimir Force Measure-mentmentioning

confidence: 99%

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Theory confronts experiment in the Casimir force measurements: Quantification of errors and precision

2004

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We compare theory and experiment in the Casimir force measurement between gold surfaces performed with the atomic force microscope. Both random and systematic experimental errors are found leading to a total absolute error equal to 8.5 pN at 95% confidence. In terms of the relative errors, experimental precision of 1.75% is obtained at the shortest separation of 62 nm at 95% confidence level (at 60% confidence the experimental precision of 1% is confirmed at the shortest separation). An independent determination of the accuracy of the theoretical calculations of the Casimir force and its application to the experimental configuration is carefully made. Special attention is paid to the sample-dependent variations of the optical tabulated data due to the presence of grains, contribution of surface plasmons, and errors introduced by the use of the proximity force theorem. Nonmultiplicative and diffraction-type contributions to the surface roughness corrections are examined. The electric forces due to patch potentials resulting from the polycrystalline nature of the gold films are estimated. The finite size and thermal effects are found to be negligible. The theoretical accuracy of about 1.69% and 1.1% are found at a separation 62 nm and 200 nm, respectively. Within the limits of experimental and theoretical errors very good agreement between experiment and theory is confirmed characterized by the root mean square deviation of about 3.5 pN within all measurement range. The conclusion is made that the Casimir force is stable relative to variations of the sample-dependent optical and electric properties, which opens new opportunities to use the Casimir effect for diagnostic purposes.

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Section: Experimental Precision In the Casimir Force Measure-mentmentioning

confidence: 92%

Section: Experimental Precision In the Casimir Force Measure-mentmentioning

confidence: 99%

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Theory confronts experiment in the Casimir force measurements: Quantification of errors and precision

2004

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“…The crossover between these behaviours is material dependent but is typically located at a lengthscale in the tens of nanometres. Similarly, the optical properties of crystalline materials are also dependent on the distribution of defects due to, for example, scattering from grain boundaries [12] or pores [13]. Defects and grain boundaries may arise from the presence of impurities in a crystal [14,15,16] and thus controlling the concentration and morphology of impurities allows the tuning of material properties.…”

Section: Introductionmentioning

confidence: 99%

Structural characterisation of polycrystalline colloidal monolayers in the presence of aspherical impurities

Gray

Mould

Royall

et al. 2015

J. Phys.: Condens. Matter

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Abstract.Impurities in crystalline materials introduce disorder into an otherwise ordered structure due to the formation of lattice defects and grain boundaries. The properties of the resulting polycrystal can differ remarkably from those of the ideal single crystal.Here we investigate a quasi-two-dimensional system of colloidal spheres containing a small fraction of aspherical impurities and characterise the resulting polycrystalline monolayer. We find that, in the vicinity of an impurity, the underlying hexagonal lattice is deformed due to a preference for 5-fold co-ordinated particles adjacent to impurities. This results in a reduction in local hexagonal ordering around an impurity. Increasing the concentration of impurities leads to an increase in the number of these defects and consequently a reduction in system-wide hexagonal ordering and a corresponding increase in entropy as measured from the distribution of Voronoi cell areas.Furthermore, through both considering orientational correlations and directly identifying crystalline domains we observe a decrease in the average polycrystalline grain size on increasing the concentration of impurities.Our data show that, for the concentrations considered, local structural modifications due to the presence of impurities are independent of their concentration, while structure on longer lengthscales (i.e the size of polycrystalline grains) is determined by the impurity concentration.arXiv:1407.8490v2 [cond-mat.soft]

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“…It might, however, be taken into account by using a modified dielectric function. 30 While the geometries of the two cases differ substantially, an initial characterization might not be able to show the difference. Figure 2 shows the scattering cross sections of both antennae upon x-polarized plane wave excitation incident from the þz-direction.…”

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confidence: 99%

Excitation and Reemission of Molecules near Realistic Plasmonic Nanostructures

Kern¹,

Martin²

2011

Nano Lett.

120

128

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The enhancement of excitation and reemission of molecules in close proximity to plasmonic nanostructures is studied with special focus on the comparison between idealized and realistically shaped nanostructures. Numerical experiments show that for certain applications choosing a realistic geometry closely resembling the actual nanostructure is imperative, an idealized simulation geometry yielding significantly different results. Finally, a link between excitation and reemission processes is formed via the theory of optical reciprocity, allowing a transparent view of the electromagnetic processes involved in plasmon-enhanced fluorescence and Raman-scattering.KEYWORDS: Surface integral equation, realistic nanoparticle, nanoantenna, near-field, SERS, fluorescence enhancement I n the past decade, one important application of plasmonic nanostructures has been the exploitation of their localized field enhancement for amplifying fluorescence and Raman scattering.1-5 On the experimental side, astonishing single-molecule sensitivity has been demonstrated 6-13 while large numbers of numerical investigations have been performed studying the effect of size and shape on the optical response, and thus the tunability of such structures. [14][15][16][17][18][19] While the performed simulations studied many aspects of the particles' geometric configuration, for the most part they were restricted to idealized geometric primitives such as cylinders and prisms, which often bear only limited resemblance to realistic, fabricated structures. 20 In addition, many reports on numerical studies show only the structures' farfield response, for example, the scattering or extinction cross sections. 21,22 Fluorescence or Raman enhancements, however, depend on the near-field properties of the structure, which can differ quite drastically from observations in the far-field. In this study, we investigate the effect of some such simplifications often made in numerical analyses on the validity of their results, our main focus set on the difference between realistic and idealized objects.When simulating nanophotonic structures, one can choose from a wide range of methods. Differential equation formulations such as the finite element method (FEM) 23 or the finite difference time-domain (FDTD) method 24 are flexible in their application but require absorbing boundary conditions for simulating isolated particles. Other specialized methods yield very accurate results, but only for particular geometries, for example, rigorous coupled-wave analysis (RCWA) for gratings and periodic geometries. 25 Integral equation (IE) methods have proved to be very useful in scattering analyses as their calculations fulfill the Sommerfeld radiation condition 26 and thus intrinsically include the complete far-field information. In particular, surface integral equation (SIE) methods, also referred to as boundary element methods (BEM), have grown in popularity in optics 27 as they unify a range of advantages otherwise not found in a single method. Unstructured m...

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Optical properties of polycrystalline metallic films

Cited by 25 publications

References 29 publications

Theory confronts experiment in the Casimir force measurements: Quantification of errors and precision

Theory confronts experiment in the Casimir force measurements: Quantification of errors and precision

Structural characterisation of polycrystalline colloidal monolayers in the presence of aspherical impurities

Excitation and Reemission of Molecules near Realistic Plasmonic Nanostructures

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