Using surface-enhanced Raman scattering (SERS) and Fourier transform infrared (FTIR) spectroscopy, we show that composites based on polyaniline (PANI) and single-walled carbon nanotubes (SWNTs) are different when they are prepared by two different methods: (1) by adding dispersed SWNTs to the polymer solutions and (2) by chemical polymerization of aniline in the presence of SWNTs. The difference originates from the irreversible chemical transformation of SWNTs in the polymerization medium. The synthesis medium used for the preparation of PANI transforms SWNTs into fragments of shorter length like closedshell fullerenes. This explains the similarity of SERS and FTIR spectra of the composites PANI/SWNTs and PANI/C 60 chemically prepared. All compounds exhibit an absorption band at 1144 cm -1 in their FTIR spectra, increasing with the carbon nanoparticules content, as a signature of a charge transfer between the constituents. Besides, the FTIR spectrum of the compounds obtained by adding SWNTs to the polymer solution display an intense absorption band with two components at 773 and 755 cm -1 , which are associated with the vibration of deformation of the benzene and the quinoid ring, respectively. This indicates a strong hindrance effect produced by the binding on the polymer chain of voluminous carbon particles as nanotubes and large fragments of nanotubes.
Resonance Raman scattering of the radial breathing mode in single wall carbon nanotubes AIP Conf.The first-and second-order Raman phonon spectra of CsPbCl 3 were measured in phase IV using Raman and resonance-Raman scattering. Twelve Raman active phonons were resolved at 32, 35.5, 42, 52, 72, 90, 110, 115, 121, 189, 200.5, and 375 cm Ϫ1 and correlated to the phonon spectrum of CsPbCl 3 in phase I. The highest frequency longitudinal optical mode is 375 cm Ϫ1 .
Surface enhanced Raman scattering (SERS) is being increasingly used for the study of the structural properties of conducting polymer thin Ðlms. It is generally accepted that the enhancement process has an electromagnetic origin, arising from the excitation of surface plasmons in the metal support on which the polymer Ðlm is deposited. However, the electromagnetic enhancement is also accompanied by a chemical process, for which available experimental data are scarce. The chemical process originates from the increase in the polarizability of the molecules at the metal surface under the action of the incident radiation, which leads to the formation of new chemical bonds with the atoms of the metal support. The present work was devoted to the study of the SERS spectra of poly(3-hexylthiophene) deposited on rough Ag and Au supports by evaporating the solvent from a solution of known concentration. The experiments revealed the existence of a chemical surface e †ect. The results obtained show that the SERS spectra depend on the oxidizing properties of the metal surface and on the nature of the solvent. This dependence is explained by the existence of some interfacial reactions that lead to the formation of interface compounds of the type MeX (Me = Ag or Au, X = Cl or O). The SERS measurements reported here reveal an increase in the intensities of the Raman lines, accompanied by a modiÐcation of the corresponding intensity ratios, when the degree of doping is increased. It was observed for the Ðrst time by SERS spectroscopy that the doping of 3-PHT with leads to the appearance of a state of disorder in the structure of the macromolecular chain, as a FeCl 3 result of steric hindrance e †ects.
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