The Experts below are selected from a list of 198984 Experts worldwide ranked by ideXlab platform
Pilar Rivas - One of the best experts on this subject based on the ideXlab platform.
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second derivative fourier transform Infrared Spectra of seaweed galactans
Journal of Applied Phycology, 1993Co-Authors: Betty Matsuhiro, Pilar RivasAbstract:The Fourier transform Infrared Spectra of agar, agarose, κ-, ι-, and λ-carrageenan, and ofChondrus canaliculatus, Iridaea ciliata, I. membranacea, I. laminarioides andGracilaria chilensis polysaccharides were recorded in the 4000–400 cm-1 region. The bands in the second derivative mode are sharper and more bands are resolved than in the normal Spectra.
Leszek Lapinski - One of the best experts on this subject based on the ideXlab platform.
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Infrared Spectra and ultraviolet tunable laser induced photochemistry of matrix isolated phenol and phenol d5
Journal of Chemical Physics, 2012Co-Authors: B M Giuliano, Leszek Lapinski, Igor Reva, Rui FaustoAbstract:Monomers of phenol and its ring-perdeuterated isotopologue phenol-d5 were isolated in argon matrices at 15 K. The Infrared (IR) Spectra of these species were recorded and analyzed. In situ photochemical transformations of phenol and phenol-d5 were induced by tunable UV laser light. The photoproducts have been characterized by IR spectroscopy supported by theoretical calculations of the Infrared Spectra. The primary product photogenerated from phenol was shown to be the phenoxyl radical. The analysis of the progress of the observed phototransformations led to identification of 2,5-cyclohexadienone as one of the secondary photoproducts. Spectral indications of other secondary products, such as the Dewar isomer and the open-ring ketene, were also detected. Identification of the photoproducts provided a guide for the interpretation of the mechanisms of the observed photoreactions.
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Infrared Spectra of methyl isocyanate isolated in ar xe and n2 matrices
Journal of Molecular Structure, 2010Co-Authors: Igor Reva, Leszek Lapinski, Rui FaustoAbstract:Abstract The Infrared Spectra of methyl isocyanate monomer isolated in cryogenic argon, xenon and nitrogen matrices were studied. Interpretation of the experimental results was supported by harmonic and anharmonic calculations carried out at the DFT, MP2 and CCSD levels of approximation. Spectral indicators of the molecule structural flexibility were examined, the most striking of these being the multiplet structure of the most intense Infrared band due to the antisymmetric stretching vibration of the N C O group. The observed quadruplet, spanning over the frequency range of nearly 100 cm −1 , between 2350 and 2250 cm −1 , was interpreted in terms of coupling with the low frequency torsion of the methyl group.
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Infrared Spectra of syn and anti isomers of benzaldoxime and pyridine 4 aldoxime an experimental matrix isolation and theoretical density functional theory study
Vibrational Spectroscopy, 2001Co-Authors: Tetyana Stepanenko, Maciej J. Nowak, Leszek Lapinski, Ludwik AdamowiczAbstract:Abstract Infrared Spectra of syn and anti isomers of benzaldoxime and pyridine-4-aldoxime isolated in low-temperature Ar and N 2 matrixes are reported. The syn isomeric forms of these compounds are highly predominant in the matrixes after deposition. These forms were identified on the basis of their Infrared Spectra. Upon UV irradiation of the matrixes, new Spectra appeared and were assigned to the anti forms of the compounds. The observed photoreactions led to photostationary states. The Infrared Spectra of the syn and anti isomers were separated and interpreted by comparison with the Spectra theoretically calculated at the DFT(B3LYP)/6-31++G ∗∗ level. Good agreement between the experimental observations and the theoretical calculations allowed for reliable assignment of the Infrared bands in the Spectra of the syn and anti isomers of both compounds.
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molecular structure and Infrared Spectra of adenine experimental matrix isolation and density functional theory study of adenine 15n isotopomers
The Journal of Physical Chemistry, 1996Co-Authors: Maciej J. Nowak, Leszek Lapinski, And Jozef S Kwiatkowski, Jerzy LeszczynskiAbstract:The Infrared Spectra of matrix-isolated adenine and its 15N isotopomers with 15N at the N(9) or N(7) positions have been studied. The experimentally observed IR Spectra were compared with the Spectra predicted at the DFT(B3-LYP)/6-31G(d,p) level. This method was also used to calculate molecular parameters (rotational constants, dipole moments) of both N(9)H and N(7)H tautomers of adenine. The agreement between experimental and theoretical Spectral positions, intensities, and isotopic shifts of the IR bands is good. That allows for reliable assignment of the IR Spectra and for conclusion that the amino-N(9)H tautomer of adenine strongly dominates in low-temperature matrices.
Maciej J. Nowak - One of the best experts on this subject based on the ideXlab platform.
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Infrared Spectra of syn and anti isomers of benzaldoxime and pyridine 4 aldoxime an experimental matrix isolation and theoretical density functional theory study
Vibrational Spectroscopy, 2001Co-Authors: Tetyana Stepanenko, Maciej J. Nowak, Leszek Lapinski, Ludwik AdamowiczAbstract:Abstract Infrared Spectra of syn and anti isomers of benzaldoxime and pyridine-4-aldoxime isolated in low-temperature Ar and N 2 matrixes are reported. The syn isomeric forms of these compounds are highly predominant in the matrixes after deposition. These forms were identified on the basis of their Infrared Spectra. Upon UV irradiation of the matrixes, new Spectra appeared and were assigned to the anti forms of the compounds. The observed photoreactions led to photostationary states. The Infrared Spectra of the syn and anti isomers were separated and interpreted by comparison with the Spectra theoretically calculated at the DFT(B3LYP)/6-31++G ∗∗ level. Good agreement between the experimental observations and the theoretical calculations allowed for reliable assignment of the Infrared bands in the Spectra of the syn and anti isomers of both compounds.
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molecular structure and Infrared Spectra of adenine experimental matrix isolation and density functional theory study of adenine 15n isotopomers
The Journal of Physical Chemistry, 1996Co-Authors: Maciej J. Nowak, Leszek Lapinski, And Jozef S Kwiatkowski, Jerzy LeszczynskiAbstract:The Infrared Spectra of matrix-isolated adenine and its 15N isotopomers with 15N at the N(9) or N(7) positions have been studied. The experimentally observed IR Spectra were compared with the Spectra predicted at the DFT(B3-LYP)/6-31G(d,p) level. This method was also used to calculate molecular parameters (rotational constants, dipole moments) of both N(9)H and N(7)H tautomers of adenine. The agreement between experimental and theoretical Spectral positions, intensities, and isotopic shifts of the IR bands is good. That allows for reliable assignment of the IR Spectra and for conclusion that the amino-N(9)H tautomer of adenine strongly dominates in low-temperature matrices.
Jerzy Leszczynski - One of the best experts on this subject based on the ideXlab platform.
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molecular structure and Infrared Spectra of adenine experimental matrix isolation and density functional theory study of adenine 15n isotopomers
The Journal of Physical Chemistry, 1996Co-Authors: Maciej J. Nowak, Leszek Lapinski, And Jozef S Kwiatkowski, Jerzy LeszczynskiAbstract:The Infrared Spectra of matrix-isolated adenine and its 15N isotopomers with 15N at the N(9) or N(7) positions have been studied. The experimentally observed IR Spectra were compared with the Spectra predicted at the DFT(B3-LYP)/6-31G(d,p) level. This method was also used to calculate molecular parameters (rotational constants, dipole moments) of both N(9)H and N(7)H tautomers of adenine. The agreement between experimental and theoretical Spectral positions, intensities, and isotopic shifts of the IR bands is good. That allows for reliable assignment of the IR Spectra and for conclusion that the amino-N(9)H tautomer of adenine strongly dominates in low-temperature matrices.
Olavm Kvalheim - One of the best experts on this subject based on the ideXlab platform.
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resolution of Infrared Spectra and kinetic analysis of mutarotation of d mannose in water
Chemometrics and Intelligent Laboratory Systems, 1999Co-Authors: Bjornvidar Grande, H Kallevik, F O Libnau, Olavm KvalheimAbstract:Abstract Infrared Spectra of a solution of d -mannose undergoing mutarotation were acquired at regular time intervals. The Spectra were first-order differentiated and sequential rank analysis was used to obtain the concentration profiles of the anomers. Least-squares were then used to resolve the Infrared Spectra of the anomers. Rate constants for the conversion from α- to β- d -mannose were calculated from the concentration profiles. The constants are slightly different from earlier reported values, while the equilibrium concentrations agree well with reported values.
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resolution of Infrared Spectra and kinetic analysis of mutarotation of d glucose in water by sequential rank analysis
Vibrational Spectroscopy, 1994Co-Authors: F O Libnau, Alfred A Christy, Olavm KvalheimAbstract:Abstract Mutarotation of d -glucose in water has been studied by attenuated total internal reflectance Fourier-transform Infrared spectrometry. Infrared Spectra of solutions of both α- d -glucose and β- d -glucose in water were acquired at regular time intervals. The Spectral profiles of the evolving mixtures were first-order differentiated and sequential rank analysis was used to obtain the concentration profiles of the anomers. The concentration profiles were subsequently used to obtain resolved Infrared Spectra of the two anomers. A crucial assumption for the resolution procedure used in this work is that the Spectral peaks of the pure anomers are symmetric in the proximity of local maxima or minima. Rate constants for the conversion of α- to β-glucose and for the conversion of β- to α-glucose have been calculated from the concentration profiles. The calculated rate constants as well as equilibrium concentrations derived from them agree well with previously reported values.
