Multipolar Contributions to the Second Harmonic Response from Mixed DiA-SDS Molecular Aggregates

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• 作者：Guillaume Revillod ; Julien Duboisset ; Isabelle Russier-Antoine ; Emmanuel Benichou ; Guillaume Bachelier ; Christian Jonin ; Pierre-Franç ; ois Brevet
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：February 21, 2008
• 年：2008
• 卷：112
• 期：7
• 页码：2716 - 2723
• 全文大小：198K
• 年卷期：v.112,no.7(February 21, 2008)
• ISSN：1932-7455

文摘

Polarization-resolved hyper-Rayleigh scattering experiments are reported for mixed suspensions of a constantconcentration of 4-(4-dihexadecylaminostyryl)-N-methylpyridinium iodide (DiA), a cationic amphiphiliccompound with a strong quadratic hyperpolarizability, and varying concentrations of sodium dodecyl sulfate(SDS), an anionic surfactant with a vanishing quadratic hyperpolarizability. It is observed that the electricdipole contribution of the HRS signal intensity attributed to the free DiA molecules in the solution decreaseswith an increasing concentration of SDS whereas the electric quadrupole contribution increases simultaneously.These changes are direct indicators of the molecular changes undergone in the solution, and in particular theappearance of centrosymmetric mixed DiA-SDS micelles. A detailed analysis of the HRS signal intensity isperformed, allowing the monitoring of the evolution of the organization of these mixed molecular systems.These experimental results are described within a general model based on the centrosymmetrical spatialorganization of the DiA probe compounds in the micelles. These results underline the potential use ofpolarization-resolved hyper-Rayleigh scattering as a noninvasive technique to investigate the molecularorganization at the nanometer scale in liquid suspensions.