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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 1717-1723 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: p-cresol and its complexes with H2O and CH3OH were cooled in a pulsed supersonic free jet and studied by resonant multiphoton ionization with time-of-flight mass analysis. Detailed mass and concentration analysis allowed an unambiguous assignment of cluster size. The electronic origins of p-cresol (H2O)1,2,3 show irregular red- and blueshifts with change of cluster size, which is referred to the bivalent role of p-cresol as proton donor and acceptor. Ab initio and semiempirical quantum chemical calculations support this interpretation and show the spectral shifts to be essentially due to the inductive effect of the solvent molecules Y exerted on X in X-H...Y. While the vibronic bands of p-cresol (H2O)2 are quite broad, those of p-cresol (H2O)3 are sharp again. The ab initio calculations show that this may be attributed to the quite rigid "open cyclic'' structure of p-cresol (H2O)3. Our experimental and theoretical investigations show a completely analogous behavior of phenol (H2O)1,2,3 clusters
    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 86 (1987), S. 3047-3048 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 2181-2189 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The nascent rotational and λ-doublet state distributions of OH produced in the reaction H+O2→OH(N,v,f )+O were probed by fast atom–laser induced fluorescence experiments at average collision energies E=100, 183, 200, 220, and 243 kJ/mol. With increasing E, the rotational product distributions become increasingly nonstatistical with a narrow peak at high rotational states, in good agreement with quasiclassical trajectory calculations on an ab initio potential energy surface. The calculations show the narrow product rotational peak to be due to an increasing specifity of the initial H–O2 configurations leading to reactions. At high E the impact parameters and initial polar angles are confined to a rather small range allowing reaction only for an optimal approach. The OH λ-doublet distributions show preference for the Π(A') component probed by R lines at all collision energies investigated. This suggests a planar reaction path and little importance of out of plane rotation of the HO2 complex at the high collision energies of the experiment. The experimental λ-doublet distributions are quantitatively compared with the degree of in-plane scattering obtained from the trajectory calculations.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 46-52 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The predissociation of cold water molecules (17–75 K) is investigated in a supersonic free jet after excitation to the C 1B1 state using simultaneous absorption of three laser photons in the range 369–374 nm. Absorption of a further photon in this wavelength range ionizes the water molecule (X 1A1 (0,0,0)→C 1B1 (0,0,0)→H2O+(X); (3+1)-multiphoton ionization spectrospcopy). The line half-widths and intensities in the rotationally resolved spectrum show a pronounced dependence on the parent rotational excitation in the C state. Supersonic cooling simplifies the spectra drastically and reduces overlap of lines, so that a considerable number of individual linewidths could be measured. The linewidth measurements and spectrum simulations show excitation of a-axis rotation to be dominant. a-axis parent molecular rotation couples the excited C 1B1 state to an unbound state of A1 electronic symmetry. The linewidth measurements point to a weaker Coriolis coupling between the C 1B1 state and a 1A2 state of H2O via rotation around the c axis. According to ab initio calculations, a water molecule in this 1A2 state dissociates essentially without barrier to O(1D)+H2. This process may explain production of nearly 10% O(1D) atoms in the wavelength range 123–125 nm.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: It is proposed that the two Λ-doublet levels of linear molecules with nonzero electronic orbital angular momentum be labeled Λ(A') and Λ(A‘), e.g., Π(A') and Π(A‘) for Π states, etc., according to the following prescription: All series of levels in which the electronic wave function at high J is symmetric with reflection of the spatial coordinates of the electrons in the plane of rotation will be designated Λ(A') for all values of J, and all those for which the electronic wave function is antisymmetric with respect to reflection will be denoted Λ(A‘). It is emphasized that this notation is meant to supplement, and not replace, the accepted spectroscopic e/f labeling and the parity quantum number. The utility of the Λ(A')/Λ(A‘) notation is that it is of most relevance in the mechanistic interpretation of reactive or photodissociative processes involving open-shell molecules.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 5012-5017 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The nascent rotational and fine structure state distributions of OH produced in the reaction H+O2→OH (N,v, f)+O were probed by fast atom-laser induced fluorescence experiments. Translationally hot H atoms were formed by photolysis of HJ and HBr at 248 and 193 nm leading to H+O2 c.m. collision energies E of 2.6, 1.9, and 0.9 eV. The rotational state distributions are compared with trajectory calculations using the ab initio potential energy surface of Melius and Blint. The OH λ-doublet distributions show preference for the π+ component which increases with increasing E suggesting less importance of out of plane rotation of the HO2 complex at high E. The alignment of OH relative to the flight direction of the H atoms is measured by polarizing analysis and photolysis laser beams. The large polarization effects directly demonstrate that the OH angular momentum vectors are preferentially parallel to the electrical vector of the dissociation laser and perpendicular to the flight direction of the H atoms.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 2995-3001 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Vibronic spectra of PhOH(NH3)n clusters with n=2–4 have been obtained by resonant two-photon ionization, recorded at the mass channels of the fragment ions (NH3)nH+. The PhOH(NH3)2–4 spectra show long progressions of at least one low frequency vibration pointing to different S0 and S1 geometries along this coordinate. In addition, the vibronic bands of the n=2 cluster are split into two components. A tunneling motion is discussed, which may be responsible for these splittings. To get more information about the structure of PhOH(NH3)2 in the electronic ground state, IR–UV double resonance spectroscopy has been applied. Possible geometries for the n=2–4 clusters are considered based on a comparison between the experimental data and theoretical results from ab initio calculations, performed at the Hartree–Fock and second-order Møller–Plesset perturbation theory level. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Chemical Physics Letters 192 (1992), S. 94-98 
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Chemical Physics Letters 218 (1994), S. 246-248 
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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