High-precision calculations of van der Waals coefficients for heteronuclear alkali-metal dimers

Van der Waals coefficients for the heteronuclear alkali-metal dimers of Li, Na, K, Rb, Cs, and Fr are calculated using relativistic ab initio methods augmented by high-precision experimental data. We argue that the uncertainties in the coefficients are unlikely to exceed about 1%.Comment: 11 pages, 2 figs, graphicx.st

Combined roughness and electric polarization for the local-field enhancement of the second harmonic response from a silver-electrolyte interface

A nanoscale rough silver film is electrodeposited from a silver cyanide aqueous solution and its growth is monitored by second harmonic generation (SHG). For growth by potential step into the diffusion controlled region, a maximum in the SHG intensity is always obtained for an equivalent silver film thickness of ∼60 nm, based on the charge consumed. The SH intensity decreases for thicker but smoother films. A study as a function of an applied static electric field for an already grown film shows that the combination of nanoscale roughness and electric polarization is able to yield large enhancement of SH signal intensities. From a microscopic analysis of the data, it is shown that the nonlinear surface current perpendicular to the interface exhibits a nonlinear dependence with the applied potential, owing to the combination of roughness and electric polarization

Second harmonic generation from tryptophan-rich short peptides: W(n)K(m) and gramicidin A

International audienceWe report the first hyperpolarizability of a series of tryptophan-rich short peptides with the respective sequence KWK, KWWK, KWWWK, KWWKWWK, where W and K stand for tryptophan and lysine. The measurements were performed with the technique of hyper-Rayleigh scattering in the bulk of an aqueous Tris buffer solution at a pH of 8.5 and a salt concentration of 150 mM at the non-resonant fundamental wavelength of 784 nm. The first hyperpolarizability of the different peptides follows a simple additive model scaling with the number of tryptophan residues contained in the peptide. However, it appears that the first hyperpolarizability response of a single tryptophan residue in the peptide strongly differs from that of an isolated tryptophan. Hence, it is therefore demonstrated that the local environment of the tryptophan residues within the peptide strongly influences its nonlinear optical response. A comparison with the first hyperpolarizability of the natural peptide gramicidin A measured in trifluoroethanol (TFE) further confirms the key role of the local environment on the first hyperpolarizability of tryptophan residues in peptides

D'une contribution dipolaire électrique à une contribution purement quadrupolaire électrique pour la génération de second harmonique de nanoparticules métalliques

La génération de second harmonique par des nanoparticules d'or dont le diamètre varie de 20 nm à 100 nm a été étudiée par diffusion hyper Rayleigh en polarisation. Pour les petites nanoparticules, la réponse non linéaire est purement dipolaire électrique indiquant une brisure de la symétrie sphérique de la forme de la particule. Pour des nanoparticules de plus grand diamètre les effets retard ne sont plus négligeables et la contribution quadrupolaire électrique devient prépondérante

First hyperpolarisability of the natural aromaticamino acids tryptophan, tyrosine and phenylalanine and the tripeptide lysine-tryptophan-lysine determined by Hyper Rayleigh Scattering

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Second Harmonic Generation, a New Approach for Analyzing the Interfacial Properties of a Tryptophan-Rich Peptide

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Optical Second Harmonic Generation of heterogeneous Langmuir films of hydrophobic gold nanoparticles at the air/water interface

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PalmitateLuciferin: A Molecular Design for the Second Harmonic Generation Study of Ion Complexation at the Air-Water Interface

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