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  • 1
    Electronic Resource
    Electronic Resource
    Molecular Rydberg states: Classical chaos and its correspondence in quantum mechanics (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 3479-3490 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The Rydberg spectrum of Na2 has been shown previously to alternate when increasing energy between "stroboscopic fringes'' which correspond to a well known separable Hund's coupling case (a), and a complex, unidentifiable intermediate coupling. We use this system as a prototypic example to test some current ideas on the correspondence between classical chaos and properties of quantum spectra. We first determine the phase space structure and transition to chaos in classical mechanics. We then determine the change in line intensities and level spacing statistics in quantum mechanics. We show that this system has the expected behavior in the semiclassical limit in the presence of classical chaos, except for a peculiarity in level spacing statistics, but that this behavior is not a signature of chaos, since the same system shows similar behavior for some values of the parameters which correspond to a nonchaotic situation in classical mechanics. We discuss also some problems related to the nonvalidity of the semiclassical limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454918
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  • 2
    Electronic Resource
    Electronic Resource
    Stark effect on the 580 nm S1←S0 transition of isobacteriochlorin using photochemical hole-burning spectroscopy (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 4335-4340 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: High resolution excitation spectra of free base isobacteriochlorin in an n-octane crystal at 4.2 K have been obtained. In the 580 nm region (the 0–0 band of the lowest-lying singlet transition of the trans tautomer) five lines were observed. Using a tunable dye laser two pairs of these lines could be photochemically interconverted, while one line did not burn. With still narrower laser excitation, holes were burned in the four convertible lines which were limited in width by the laser output (0.07 cm−1). Electric fields were applied along each of the crystal axes and Stark splittings of the spectral lines and holes were observed. The splittings are linear over the range 1.21 to 50.0 kV/cm. The magnitude of the total dipole moment change (Δμ) for all lines was found to be 1.64 D; this is much larger (∼7×) than the value measured in free base chlorin. Also, the direction of this vector is a function of the position of the tautomers inner protons; it rotates 90° in going from one trans tautomer to the other. The direction cosines of the Δμ¯'s indicate that free base isobacteriochlorin's orientation in the n-octane crystal is similar to that of free base chlorin, but with the second exterior reduced double bond rotated about 25° out of the alkane chain plane. Furthermore, the burning pattern of the 580 nm 0–0 bands verifies the earlier hypothesis that these are due to the trans tautomer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451894
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  • 3
    Electronic Resource
    Electronic Resource
    Stark effect on the S1←S0 transition of 1,4-dihydroxyanthraquinone (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 3048-3050 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452009
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  • 4
    Electronic Resource
    Electronic Resource
    Raman spectra of rhodium trimers in argon matrices (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 7178-7181 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Resonance Raman spectra of rhodium trimers (Rh3) in argon matrices have been obtained for the first time. Our samples are prepared by neutralizing a mass-filtered beam of trimer ions. Although the absorption spectrum of our optically thin samples failed to show any obvious transitions, a rich Raman spectrum was found for laser excitation wavelengths between 545 nm and 593 nm. Three fundamentals, corresponding to normal modes of a bent (C2v) molecule can be assigned with up to four overtones in the symmetric stretch. Using standard techniques, we obtained for this mode ωe=322.4(6) cm−1, with ωexe=0.49(10) cm−1. The resulting stretching force constant is ke=2.10±0.01 mdyn/Å. Assuming a Morse potential governs the symmetric stretching normal coordinate, we obtain an atomization energy of De=6.6±1.4 eV. The asymmetric stretch and bend are found at 259 cm−1 and 247.9(8) cm−1, respectively. A line at 400 cm−1 is observed, which does not fit the normal mode scheme of the ground state. This is assigned as the origin of a low lying electronic state. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1312283
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  • 5
    Electronic Resource
    Electronic Resource
    Raman and absorption spectrum of mass-selected lutetium dimers in argon matrices (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 10202-10206 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report on the absorption, resonance Raman, and Raman excitation profile spectra of mass selected lutetium dimers in argon matrices. Two broad absorption regions were found between 415 and 545 nm with peaks at 418, 433, 452, 472, 505, 540 nm, and between 635 and 660 nm with peaks at 640 and 652 nm. Resonance Raman spectra were obtained by excitation into one of these regions with the visible light of an Ar ion laser between 458 and 514 nm. Two progressions were assigned to lutetium dimers. We interpret them to represent two distinct electronic states: A ground-state X and an excited state A. For the ground (X) state, we obtain ωe=121.6±0.8 cm−1 with ωexe=0.16±0.10 cm−1, leading to a spectroscopic dissociation energy of 2.9±1.8 eV, and force constant ke=0.76±0.01 mdyne/Å. The lowest excited electronic state (A) has an origin at 210.7 cm−1 and almost identical vibrational parameters. Comparison of spectroscopic properties of lanthanide dimers is discussed, and evidence is presented that lutetium should occupy the position normally given to lanthanum in the periodic table. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1322635
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  • 6
    Electronic Resource
    Electronic Resource
    Absorption, excitation, and resonance Raman spectra of Ce2, Pr2, and Nd2 (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 2233-2237 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report the absorption, resonance Raman, and excitation spectra of mass selected cerium, praseodymium, and neodymium dimers in argon matrices. Absorption bands were found for each sample. The excitation profiles give more sensitive detail and resemble absorption spectra. Resonance Raman spectra give single progressions for which Ce2: ωe=245.4±4.2 cm−1, Pr2: ωe=244.9±1.2 cm−1, and Nd2: ωe=148.0±1.9 cm−1, ωexe=0.7±0.4 cm−1. Comparison among lanthanide dimers is discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.482037
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  • 7
    Electronic Resource
    Electronic Resource
    Spectroscopy of mass-selected gadolinium dimers in argon matrices (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 9780-9782 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report on the absorption, resonance Raman, and Raman excitation profile spectra of mass-selected gadolinium dimers in argon matrices. Two dimer absorption bands were found between 570 and 660 nm. The Raman excitation profile resembles the dimer absorption spectrum very well. Resonance Raman spectra, obtained by excitation into this region with dye laser radiation, give a single progression with up to four Stokes transitions. These data give ωe=138.7±0.4 cm−1 with ωexe=0.3±0.1 cm−1, leading to a spectroscopic dissociation energy of 2.1±0.7 eV. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481616
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  • 8
    Electronic Resource
    Electronic Resource
    Vibrational dynamics up to the dissociation threshold: A case study of two-dimensional HOCl (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 9610-9621 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This work is aimed at extending recent studies dealing with the highly excited vibrational dynamics of HOCl [J. Chem. Phys. 111, 6807 (1999); J. Chem. Phys. 112, 77 (2000)], by taking advantage of the fact that the OH-stretch remains largely decoupled from the two other degrees of freedom up to and above the dissociation threshold. The molecule is thus reduced to a two-dimensional (2D) system by freezing the OH bond length to its equilibrium value. All of the calculated bound states of the 2D system, as well as the first 40 resonances, can be assigned with a Fermi polyad quantum number. The bifurcation diagram of the principal families of periodic orbits (POs) is extended to higher energies compared to 3D studies. In particular, the birth of "inversion" states (states exploring two equivalent wells connected through the linear HOCl configuration) is related to a period-doubling bifurcation of the families of bending POs, while "dissociation" states (states for which the energy flows back and forth along the dissociation pathway) are shown to lie on top of three successive families of POs born at saddle-node bifurcations. Based on the derivation of a classical analogue of the quantum Fermi polyad number, the energies of particular quantum states and classical POs are plotted on the same diagram for the 2D ab initio surface and are shown to agree perfectly. In contrast, comparison of classical Poincaré surfaces of section and quantum Husimi distributions suggests that the classical dynamics of 2D HOCl is much more chaotic than the quantum dynamics. This observation is discussed in terms of the quantum/classical correspondence, and particularly of the vague tori introduced by Reinhardt. It is nevertheless shown that quantum and classical mechanics agree in predicting a slow intramolecular vibrational energy redistribution (IVR) between the OCl stretch and the bend degrees of freedom. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1321031
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  • 9
    Electronic Resource
    Electronic Resource
    Resonance Raman spectrum and excitation profile of mass-selected zirconium trimers (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 9527-9529 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present the resonance Raman and Raman excitation profile of mass-selected zirconium trimers in argon matrices. In the Raman spectra, two fundamentals and one overtone are observed. Average Raman shifts, along with standard deviations (in parentheses) are 176.7 (13) cm−1 (ν2), 258.0 (12) cm−1 (ν1), and 516.1 (8) cm−1 (2ν1). The ratio of the frequencies of the two lowest lines (ν1/ν2) is 1.46, which is very close to (square root of)2. This is indicative of a symmetrical equilateral geometry (D3h). In such a case we expect two normal frequencies, one for a totally symmetric stretch of symmetry a′1 (ν1) and a doubly degenerate bend of symmetry e′(ν2). The Raman excitation profiles of the ν1(a′1) line shows two broad maxima: one near 491 nm and the other near 614 nm. The ν2 (e′) profile shows a broad region of intensity only near 614 nm. With the aid of theory we assign the 614 nm band to be 1A′1−1E′ (x,y polarized) while the 491 nm band must be 1A′1−1A″2 (z polarized). © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469966
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  • 10
    Electronic Resource
    Electronic Resource
    Raman spectra of mass-selected cobalt dimers in argon matrices (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 9280-9282 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report absorption and Raman spectra for cobalt dimers in an argon matrix prepared by the mass-selected ion deposition technique. A weak dimer absorption band was found between 425 and 485 nm. Resonance Raman spectra (obtained by exciting between 457.9–488.0 nm) give ωe‘= 296.8(54) cm−1 with ωexe‘ = 2.2(8) cm−1. The dicobalt data are discussed in terms of results from recent photodetachment experiments which suggest a changeover from d–d bonding to s–s bonding along the series Fe2→Cu2. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467957
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