We introduce a new experimental technique referred to as ellipsometric Raman spectroscopy (ERS) to quantify the Raman optical activity (ROA) where ellipsometry is combined with Raman spectroscopy. The Stokes parameters were determined for Raman scattered light using Fourier decomposition in measurements with achromatic optical components in a nine-point method. We tested the methodology with ultrapure water, a well-known chiral alcohol, and a chiral polymer, and we show that ERS allows for studying not only the vicinities of chiral carbons but also molecular species coupled to form chiral structures. Furthermore, in ERS, isotropic and anisotropic scattering contribute equally, thus making it possible to analyze the low-wavenumber region in samples such as the chiral polymer studied here, for which the ROA signal probably arises mainly from isotropic scattering.
Poly(3-alkylthiophene) (P3ATs) have been extensively used in photovoltaic devices such as a p-type organic Semiconductors. However, several electronic properties of P3ATs present energy transfer inter-and intra-chains that have direct consequences on the performance of optoelectronic devices. Traditionally electrochemical techniques, such as cyclic voltammetry, chronoamperometry and chronocoulometry, have been applied to process polymer thin ilms and unconventional spectroscopy techniques are used to characterize the electronic properties. In the present work, we used an innovative technique called ellipsometry emission to investigate the optical properties of P3AT ilms. We propose a new approach to study the electrochemical synthesize and unintentional doping processes of polymeric systems. We showed a strong correlation between the electrochemical synthesis and the optical properties controlling the ilm growth conditions for P3ATs. The results obtained in the present study can be potentially utilized for applications in organic devices, mainly in photovoltaic cells when the ilm deposition and the optical properties control are relevant.
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