Model for reflectance anisotropy spectra of molecular layered systems

Mendoza, Bernardo S.; Vázquez-Nava, R. A.

doi:10.1103/physrevb.72.035411

Cited by 17 publications

(10 citation statements)

References 10 publications

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“…In a recent theoretical work [12,13], the characteristic oscillatory line shape of the RAS signal in the Soret band region, observed on LB samples after a certain critical coverage value [11], is explained in terms of dipole interactions between the porphyrin molecules arranged in an ordered lattice onto the substrate. The total lineshape results by adding the contribution of the single layers, in turn depending upon the orientation of the molecules in the layer, due to the interaction with the other molecules.…”

Section: Resultsmentioning

confidence: 98%

“…The interacting-dipoles model [12,13], although capable to describe the experimental results, is subject to a main criticism: all the values of the structural parameters characterizing the physical system are obtained phenomenologically, and not by first principles calculation (that probably represents a task too complicated to be performed at this stage). This means that the quality of the final result (exhibiting a nice agreement with experiment) should be relaxed, unless some independent argument is found to strengthen the main hypothesis.…”

Section: Resultsmentioning

confidence: 99%

“…Very recently, a new phenomenological model has been proposed to explain this RAS behaviour [12,13]: each LB layer is modelled as an ordered array of dipoles, and the dipole-dipole interaction is treated within the local fields theory. The resulting anisotropy spectrum for a given layer depends upon two parameters defining the average orientation of the molecules: the tilt angle θ (defined with respect to the normal to the substrate plane) and the azimuthal angle φ.…”

Section: Originalmentioning

confidence: 99%

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Optical anisotropy and gas sensing properties of ordered porphyrin films

Bussetti

Corradini

Goletti

et al. 2005

Physica Status Solidi (b)

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Ordered films of porphyrins are routinely obtained by Langmuir-Blodgett technique, with a thickness control at the level of a single monolayer. The study of their optical anisotropy by reflectance anisotropy spectroscopy (RAS) has evidenced an interesting modification of the spectral line shape around the Soret band of the porphyrin layer after a certain critical thickness has been deposited onto the substrate. This finding has been connected to a structural modification of the film, although a detailed model was lacking until now. Recently, a new theoretical study based on the local field interaction has proposed to explain the RAS spectra in terms of the orientation of the molecules in a layer, that would change from layer to layer as the system is assembled. In order to test the model, we have collected new experimental data studying the modification of the optical anisotropy during exposure of the film to a gas (ethanol), mimicking the application for gas sensing analysis. The results show that the model is adequate to describe the real system: reordering of the layer during or after growth originates the anomalous spectra

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Originalmentioning

confidence: 99%

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Optical anisotropy and gas sensing properties of ordered porphyrin films

Bussetti

Corradini

Goletti

et al. 2005

Physica Status Solidi (b)

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“…Our choice of a particularly simple model dielectric function for our hypothetical overlayer was intended to remove from the discussion the specialities that arise in particular materials and to aid visual data analysis. Despite this simplicity, however, such models have been useful in describing the optical properties and hence RAS signatures of semiconductors interface states [13,14] and organic thin films [15], for which RAS has been found to show high sensitivity to molecular orientation [16][17][18].…”

Section: ¼ 0-(normal Incidence)mentioning

confidence: 99%

Molecular orientation studied by reflection anisotropy spectroscopy

Lane

Isted

Cole

2010

Physica Status Solidi (b)

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A description of the reflection anisotropy spectroscopy (RAS) results from oriented thin films is presented. The RAS signals of a 1 nm thick film are simulated to investigate the effect of molecular tilt on the RAS response of the system. Whilst the spectroscopic measurements themselves appear to be relatively insensitive to the effects of the tilt, the variation of the RAS signal with rotation of the sample azimuthal angle sees sensitivity to out of surface plane anisotropy, characterized by a sin u s effect.

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“…The adsorption of atoms on clean surfaces has been studied during a long time [3,[11][12][13]. Among the studied interfaces, Sb on clean GaAs(110) surfaces represents a prototypical system since deposition, at room temperature, of 1 ML of Sb on clean GaAs(110) surface produces a stable, ordered adsorbate (1 × 1) structure [14][15][16].…”

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confidence: 99%

Theoretical model for adsorption of Sb on the GaAs(110) surface

Mendoza

Arzate

Vázquez-Nava

2005

phys. stat. sol. (c)

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We present a model for studying the adsorption of Sb atoms on the clean GaAs(110) surface and analyse the consequences of the adsorption on the reflectance anisotropy spectroscopy (RAS). A 1 × 8 unit cell is taken as a basis of the Sb-covered GaAs(110) structure. We allow the Sb-covered surface to be disordered by letting every surface atom move freely around its equilibrium position. In order to obtain a representative RAS spectrum of the surface we generate an ensemble with N different structural realizations of the surface and the ensemble RAS average is performed.

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Model for reflectance anisotropy spectra of molecular layered systems

Cited by 17 publications

References 10 publications

Optical anisotropy and gas sensing properties of ordered porphyrin films

Optical anisotropy and gas sensing properties of ordered porphyrin films

Molecular orientation studied by reflection anisotropy spectroscopy

Theoretical model for adsorption of Sb on the GaAs(110) surface

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