Nitrogen pressure-broadening coefficients have been measured in the 841 cm(-1) nu(10) band of allene (H(2)C&dbond;C&dbond;CH(2)). The high-resolution absorption infrared spectra were recorded by a FTIR spectrometer at a temperature of 201 K. The Voigt line profile, convolved with a sinc instrument function, was applied to the fit of the observed rovibrational lines. No regular J or K dependence of the broadening coefficients was observed for this strong symmetric-top-molecule band. The power-exponential-gap (PEG) fitting law and the infinite-order-sudden (IOS) scaling law were modified for the fit of the N(2)-broadening coefficients. The wavefunction mixing arising from the nu(10)/nu(9) Coriolis resonance was taken into account for the IOS law. A total of 180 broadening coefficients measured at 201 K were reproduced with an accuracy of 8.6 and 7.9% by the PEG and IOS laws, respectively. Copyright 1999 Academic Press.
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http://dx.doi.org/10.1006/jmsp.1999.7977 | DOI Listing |
The actinobacterial coproheme decarboxylase from catalyzes the final reaction to generate heme via the "coproporphyrin-dependent" heme biosynthesis pathway in the presence of hydrogen peroxide. The enzyme has a high reactivity toward HO used for the catalytic reaction and in the presence of an excess of HO new species are generated. Resonance Raman data, together with electronic absorption spectroscopy and mass spectrometry, indicate that an excess of hydrogen peroxide for both the substrate (coproheme) and product (heme ) complexes of this enzyme causes a porphyrin hydroxylation of ring C or D, which is compatible with the formation of an iron chlorin-type heme species.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
October 2022
Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, D - 38106 Braunschweig, Germany. Electronic address:
High resolution infrared spectra of CHD were recorded in the region of 550-1950 cm with a Bruker IFS125 HR Fourier transform infrared spectrometers and rotational structures of the five lowest strongly interacting ν, ν,ν,ν and ν bands were analyzed. The number of about 28000 transitions (4200/6800/5600/5000/6400 for the bands ν,ν,ν,ν and ν) with J = 40 and K = 20 were assigned to these five bands. The weighted fit of 3990 upper energy values obtained from the experimentally recorded transitions was made with a Hamiltonian which takes into account resonance interactions between all studied bands as well as with the sixth ν band which was considered in this case as a "dark" one.
View Article and Find Full Text PDFJ Phys Chem A
March 2020
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
The high resolution far-infrared spectrum of -butadiene has been reinvestigated by Fourier-transform spectroscopy at two synchrotron radiation facilities, SOLEIL and the Canadian Light Source, at temperatures ranging from 50 to 340 K. Beyond the well-studied bands, two new fundamental bands lying below 1100 cm, ν and ν, have been assigned using a combination of cross-correlation (ASAP software) and Loomis-Wood type (LWWa software) diagrams. While the ν analysis was rather straightforward, ν exhibits obvious signs of a strong perturbation, presumably owing to interaction with the dark ν + ν state.
View Article and Find Full Text PDFJ Phys Chem A
February 2016
The North Carolina State University, Department of Physics, Raleigh, North Carolina 27695-8202, United States.
Resonance Raman spectroscopy provides much stronger Raman signal levels than its off-resonant counterpart and adds selectivity by excitation tuning. Raman preresonance of benzene has been well studied. On-resonance studies, especially at phonon-allowed absorptions, have received less attention.
View Article and Find Full Text PDFJ Phys Chem A
February 2015
Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, People's Republic of China.
The photophysics and photochemistry of thioacetamide (CH3CSNH2) after excitation to the S2 electronic state were investigated by using resonance Raman spectroscopy in conjunction with the complete active space self-consistent field (CASSCF) method and density functional theory (DFT) calculations. The A-band resonance Raman spectra in acetonitrile, methanol, and water were obtained at 299.1, 282.
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