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The frequency-dispersed birefringence and dichroism of an electronically nonresonant liquid excited and probed by ultrafast pulses in an optically heterodyned detected configuration is reported. The nominally putative dichroic response of a transparent sample is shown to result from π out-of-phase contributions of Stokes and anti-Stokes third-order polarization components on, respectively, the red and blue sides of the probe pulse spectrum and are derived from CSRS and CARS type resonances. The strong corresponding nondispersed birefringent response, in contrast, results from the in-phase combination of these Stokes and anti-Stokes polarization components. Thus, by observing the dispersed probe pulse to the red or blue of the central carrier frequency, the various density matrix components, or pathways in time evolution history, contributing to either a dichroic or birefringent measurement may be more selectively viewed. The contribution of a particular nuclear response is enhanced when the observed frequency within the probe pulse spectrum is tuned to be either one quantum to the red or blue of the carrier frequency. This frequency-filtering technique can be used to enhance weak features in the total response, allow the determination of isotropic and anisotropic contributions to a nuclear response, and help probe the homogeneous and inhomogeneous character of the low-frequency Raman active density of states commonly observed in these two-pulse responses of nonresonant liquids. These effects are illustrated by the OHD birefringence and dichroism of CHCl3.

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In this paper, we report on the synthesis and characterization of cobalt aggregates electrochemically incorporated on composite polypyrrole films. XAS (X-ray absorption spectroscopy) was used to probe the atomic local order in these composites and to furnish new insights into the metal/polymer interaction. A complete understanding of the incorporation process and its evolution was achieved by in situ XAS measurements at different stages of the electrochemical process. These results indicate that the reaction starts with the Co 2+ entrapped in the polymeric matrix as a complex [-[(C 4 H 2 N) 3 CH 3 (CH 2 ) 11 OSO 3 -] 6 Co 2+ ]. The reduction of this complex leads to the synthesis of Co aggregates in the film. Measurements at the O and N K edges evidence that the main interaction between Co aggregates and the polymer is verified via Co-N bonds, the N originating from the polypyrrole (PPy) amine group. The pH effect on the metal/polymer interaction is discussed. Scanning electron microscopy (SEM) measurements show the formation of dendritic-like cobalt aggregates on the film surface. The magnetic response obtained by in situ alternating gradient field magnetometry (AGFM) allows prediction of the possibility of obtaining a magnetic polymer with superparamagnetic particles with sizes below 10 nm. Our results are the first steps toward the development of an advanced material with exciting potential for future recording media application.