Hydrodynamic model for sum and difference frequency generation at metal surfaces

Maytorena, Jesús A.; Mochán, W. Luis; Mendoza, B.S.

doi:10.1103/physrevb.57.2580

Cited by 26 publications

(12 citation statements)

References 51 publications

(63 reference statements)

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“…In addition, the local Drude model, although widely used for such simulations, leads to a rapid growth of the dielectric function in the infrared, having a strong impact on the value of a f (ω1,ω2) under the long wavelength approximation. A more realistic model, either nonlocal 12,37,69 , including a hydrodynamic pressure term 4,39,41 , or even more sophisticated 43 , and the limitation of the rise of a f 40 , could help refine the definition of silver and gold properties and improve the accuracy of the modeled free electron response.…”

Section: Discussionmentioning

confidence: 99%

Nonlinear optical response of a gold surface in the visible range: A study by two-color sum-frequency generation spectroscopy. II. Model for metal nonlinear susceptibility

Busson

Dalstein

2018

The Journal of Chemical Physics

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We present a modeling of the nonlinear optical response of a metal surface in order to account for recent experimental results from two-color Sum-Frequency Generation (SFG) experiments on gold. The model allows calculating the surface and bulk contributions and explicitly separates free and bound electron terms. Contrary to the other contributions, the perpendicular surface component is strongly model-dependent through the surface electron density profiles. We consider three electron density schemes at the surface, with free and bound electrons overlapping or spilling out of the bulk, for its calculation. The calculated SFG signals from the metal rely only on bulk quantities and do not need an explicit definition of the density profiles. In the particular case of gold, when the free electrons overlap with the bound ones or spill out of the bulk, the free electron response completely dominates through the perpendicular surface terms. When the bound electrons spill out, the situation is more balanced, still in favor of the free electrons, with lower amplitudes and different dispersion line shapes. As for silver, the free electron contributions dominate and the calculated slow amplitude growth from blue to red follows the experimental trends.

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Section: Discussionmentioning

confidence: 99%

Nonlinear optical response of a gold surface in the visible range: A study by two-color sum-frequency generation spectroscopy. II. Model for metal nonlinear susceptibility

Busson

Dalstein

2018

The Journal of Chemical Physics

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“…In addition, the infrared free electron polarizability may be overestimated as a result of using a simple Drude model. 5,17,18 This could also impact on the balance between free and bound electron terms in the total nonlinear surface susceptibility. As a consequence, in the interface region, neither the actual electron densities nor the polarizabilities are accurately determined.…”

Section: The Interband Scenariomentioning

confidence: 99%

Nonlinear optical response of a gold surface in the visible range: A study by two-color sum-frequency generation spectroscopy. III. Simulations of the experimental SFG intensities

Busson

Dalstein

2018

The Journal of Chemical Physics

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We model the amplitude line shape and absolute phase of the infrared-visible sum-frequency signals produced by a thiolated polycrystalline gold surface as a function of the visible wavelength. We follow two hypotheses: in the interband scenario, the resonant features are attributed to interband transitions, whereas in the effective surface state scenario, they stem mostly from the excitation of surface transitions. We find that both scenarios lead to a satisfactory account of the experimental data and that only free electrons may spill out of the gold bulk, as expected. For the interband scenario, the balance between free and bound electron contributions to sum-frequency generation has to be adjusted to fit the data. The surface transitions are shown to take their origin inside gold and we investigate the surface states involved in such transitions, with a comparison to the silver surfaces. We finally provide a work program dedicated to discriminate between the two scenarios.

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“…SHG is also a sensitive probe of surfaces and interfaces as they intrinsically break inversion symmetry. Studies include those of surfaces and domain walls in ferroelectrics, melting of metal surfaces, catalytic processes, liquid crystals, biological surfaces, and many more. The SHG processes that involve the magnetic field of light are typically weaker; however, they can be sensitive to time reversal symmetry, and hence to the magnetic structure of materials.…”

Section: Introductionmentioning

confidence: 99%

Probing Ferroelectrics Using Optical Second Harmonic Generation

Denev

Lummen

Barnes

et al. 2011

Journal of the American Ceramic Society

300

307

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Nonlinear optics is an essential component of modern laser systems and optoelectronic devices. It has also emerged as an important tool in probing the electronic, vibrational, magnetic, and crystallographic structure of materials ranging from oxides and metals, to polymers and biological samples. This review focuses on the specific technique of optical second harmonic generation (SHG), and its application in probing ferroelectric complex oxide crystals and thin films. As the dominant SHG interaction mechanism exists only in materials that lack inversion symmetry, SHG is a sensitive probe of broken inversion symmetry, and thus also of bulk polar phenomena in materials. By performing in-situ SHG polarimetry experiments in different experimental conditions such as sample orientation, applied electric field, and temperature, one can probe ferroelectric hysteresis loops and phase transitions. Careful modeling of the polarimetry data allows for the determination of the point group symmetry of the crystal. In epitaxial thin films with a two-dimensional arrangement of well-defined domain orientations, one can extract information about intrinsic material properties such as nonlinear coefficients, as well as microstructural information such as the local statistics of the different domain variants being probed. This review presents several detailed examples of ferroelectric systems where such measurements and modeling are performed. The use of SHG microscopic imaging is discussed, and its ability to reveal domain structures and phases not normally visible with linear optics is illustrated.

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Hydrodynamic model for sum and difference frequency generation at metal surfaces

Cited by 26 publications

References 51 publications

Nonlinear optical response of a gold surface in the visible range: A study by two-color sum-frequency generation spectroscopy. II. Model for metal nonlinear susceptibility

Nonlinear optical response of a gold surface in the visible range: A study by two-color sum-frequency generation spectroscopy. II. Model for metal nonlinear susceptibility

Nonlinear optical response of a gold surface in the visible range: A study by two-color sum-frequency generation spectroscopy. III. Simulations of the experimental SFG intensities

Probing Ferroelectrics Using Optical Second Harmonic Generation

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