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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 646-654 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The infrared spectra of the ν3, ν4, and ν6 bands of formaldehyde in the region from 890 cm−1 to 1580 cm−1 have been obtained at high resolution using tunable diode laser (TDL) and Fourier transform-infrared (FT-IR) spectroscopy. The transition frequencies have been analyzed using a Hamiltonian including terms through sextic in centrifugal distortion and including five interstate vibration–rotation coupling terms. Excited state pure rotational transitions are also included in the data, and their frequencies are reproduced well. Individual measured line intensities are used to determine dipole derivatives and band strengths using the fully coupled, asymmetric top eigenvectors.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 1504-1510 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: High resolution spectra of H2O2, recorded by means of Fourier transform spectroscopy between 30 and 460 cm−1, have been analyzed leading to the determination of the rotational levels of the torsional states (n,τ) for n=0,1,2,3. In order to reproduce these energy levels, Watson type Hamiltonians have been used and it has been possible to observe a staggering of the levels with n=2 and 3 caused by the cis barrier. The torsional band centers have then been fitted using a torsional Hamiltonian of the form {Bγγ,J2γ} +V(γ) with the potential function V(γ) written as V(γ)=V1 cos 2γ+V2 cos 4γ+V3 cos 6γ+V4 cos 8γ where the torsional coordinate 2γ is the dihedral angle defining the relative position of the two O–H bonds. The potential constants in cm−1 are V1=1036.97±23.1 cm−1, V2=657.53±5.2 cm−1, V3=50.89±3.3 cm−1, V4=2.524±0.83 cm−1 which correspond to barrier heights Vtrans =387.07±0.20 cm−1, Vcis =2562.8±60 cm−1, and to a potential minimum located at 2γ=111.9°±0.4° from the cis configuration. It is also shown that the rotational constants derived from the fit to the experimental rotational levels cannot be reproduced using a model which does not take into account vibrational corrections.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0649
    Keywords: 33.20E ; 42.55H
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract High-resolution Fourier transform spectroscopy has been applied to confirm previously proposed assignments for nine far infrared (FIR) laser lines from the CH3-deformation state of CH3OH and one line from the CH3-rocking state. Accurate frequencies are deduced for the observed and other predicted FIR laser transitions. FIR torsional branch frequencies in the ground state which were used in the confirmation are presented. Comments are also made on the OH-bending mode of CH3OH.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 6 (1985), S. 199-233 
    ISSN: 1572-9559
    Keywords: Fourier transform infrared spectroscopy ; Deuterated water vapor ; Laser frequencies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using high resolution Fourier transform spectra, thev 2 band of D2O has been analysed leading to an extensive and precise set of rotational energy levels of the (0 1 0) vibrational state. These levels are reproduced very satisfactorily with a Watson type Hamiltonian and precise rotational constants as well as the band centerv 2 = 1178.3789 ± 0.0005 cm-1 are determined. A total of 61 line intensities were measured, much attention being paid to a possible contamination of the D2O sample by HDO. A least squares fit of the intensity data has provided us with an expansion of the transition moment operator of thev 2 band from which the first derivative $$\left( {\frac{{\partial ^x \mu }}{{\partial q_2 }}} \right)_e $$ = 0.1690 ± 0.0030 D has been deduced. Finally the complete synthetic spectrum of this band has been computed. All these results have been used to derive improved frequencies for the known pumped and far-infrared laser lines of D2O and to predict new possible coincidences with the available CO2 laser lines.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 8 (1987), S. 803-825 
    ISSN: 1572-9559
    Keywords: far-infrared (FIR) spectroscopy ; methylamine ; torsion ; inversion ; large-amplitude motions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The far-infrared (FIR) spectrum of CH3NH2 has been studied in the 25–125 cm−1 region at a resolution of 0.005 cm−1 with a BOMEM Fourier transform spectrometer. All of therR branches with K rotational quantum number from 5 to 13 have been identified for A-a and E-a torsion-inversion symmetries in the ground torsional state, as well as some branches of A-s and E-s symmetries and some in excited torsional states. The observed branches have been fitted to series expansions in order to determine the branch origins.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 9 (1988), S. 1119-1140 
    ISSN: 1572-9559
    Keywords: Far-infrared (FIR) spectra ; methanol ; torsion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The high-resolution far-infrared (FIR) Fourier transform spectrum of13CH3OH has been studied from 25–350 cm−1, andb-typerR-branches in the torsional ground state have been assigned. The branches have been fitted to phenomeno-logical expansion parameters, which reproduce the branch frequencies generally to well within ±0.001 cm−1. An interesting and relatively novel ΔK=4 perturbation, localized to levels around J=18, has been observed between (nτK)=(019) and (125) states.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 8 (1987), S. 1471-1482 
    ISSN: 1572-9559
    Keywords: Far-infrared (FIR) lasers ; methanol ; torsion ; FIR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is proposed that a number of the high-frequency far-infrared (FIR) laser lines observed when CH3OH is optically pumped by high-power CO2 TEA lasers can be identified as refilling torsional transitions within the vibrational ground state. Assignments are presented for 8 such TEA-pump/FIR-laser refilling systems. To provide support for the assigned laser frequencies, high-resolution Fourier transform FIR spectra of CH3OH have been obtained and partially analyzed in the torsional transition region.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1572-9559
    Keywords: Far-infrared (FIR) lasers ; methanol ; IR and FIR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract High-resolution infrared (IR) and far infrared (FIR) Fourier transform absorption spectra have been employed to investigate assignments of FIR laser lines reported from optically-pumped13CH3OH. The spectroscopic measurements are used in conjunction with the reported IR pump and FIR laser frequencies to form closed combination loops for several systems, serving to confirm the assignments and in some cases to improve the accuracy of the FIR laser frequencies. Frequency predictions from combination differences are also presented for a number of potential new FIR laser lines.
    Type of Medium: Electronic Resource
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