Development of Fourier Transform Ultraviolet. Visible. Near-Infrared Raman Spectroscopy and its Application to Structural Chemistry

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Fourier transform (FT) Raman spectrophotometer with 1064 nm excitation is constructed. Resonance Raman spectra of conducting polymers and photosynthetic pigments are studied.(1) Construction of 1064 nm excited FT-Raman spectrophotometerAn FT-Raman spectrophotometer consists mainly of FT-NIR spectrophotometer (JEOL JIR-5500) with an InGaAs detector, continuous-wave Nd : YAG laser (CVI YAGMAX C-92), optics for collecting scattered light, filters for rejection of Rayleigh scattering, etc.(2) Conducting polymersResonance Raman spectra of trans-polyacetylene (PA) films doped with iodine or Na and poly (para-phenylenevinylene) (PPV) films doped with H_2SO_4 or Na are obtained with 1064 nm excitation. As Na content of Na-doped PA increases, two spectral changes corresponding to the increase of electrical conductivity and the appearance of Pauli susceptibility are observed. Raman spectra of Na-doped PPV are ascribed to negative bipolarons on the basis of the data of the divalent anion of an appropriate oligomer.(3) Photosynthetic pigmentsThe 1064 nm excited Raman spectra of bacteriochlorophyll a (BChl a) in various solid films and in chromatophores from a blue-green mutant of Rhodobacter sphaeroides are obtained. Molecular interactions and arrangements of Bchla are discussed on the basis of the C=O stretching wavenumber and CC stretches which are marker bands of the coordination number of central Mg.