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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 5589-5597 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Polarized two-photon photodissociation of NO2 in the region of 480 nm yields NO(v‘=0) with an anisotropic distribution of J. Measured polarization ratios are compared to quantum mechanical calculations for a range of expected ratios for the various isolated and mixed branches of the NO X˜2Π1/2→A˜ 2Σ+ transition. Theoretical results show that main branches and their respective satellites (e.g., R11 and R21 branches) have the same transition moment directionally, though their intensities are in general different, implying that care is needed in interpreting polarization data from the mixed branches, such as (Q21+R11) or (Q11+P21), which measure the Π+ and Π− Λ doublet, respectively. Recognition of this fact is particularly important for properly separating the consideration of electron density distributions of Λ doublets from transition moment directionalities, as this has been a source of confusion in the literature. The measured results indicate that the principal two-photon photoexcitation pathway in NO2 photolysis is 2A1→1 2B2→2 2B2, with moderate A‘ state mixing in the intermediate.
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 5968-5968 
    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 87 (1987), S. 360-369 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Quantum states of NO2 are selected and then photodissociated by resonant two-photon photoexcitation. The total photolysis energy is scanned over a region from 50 cm−1 below to 300 cm−1 above the threshold for production of NO(X˜ 2Π)+O(1D). This channel yielding excited oxygen is observed to dominate the production of vibrational ground state NO. Diatomic product J and Λ doublet state distributions are probed by resonant two-photon ionization. The photodissociation cross section for production of specific NO quantum states is found to be structured in the photolysis wavelength. This structure is assigned to intermediate resonance in the two-photon photolysis. Rotational structure is identified in this pattern, and confirmed by separate optical–UV–double resonance spectroscopy using the same intermediate states in combination with levels of the 3pσ 2Σ+u Rydberg state of NO2. Though photodissociation dynamics are found to be a very sensitive function of photolysis wavelength, different wavelengths that promote different transitions through the same intermediate state yield very similar dynamics. The existence and apparent patterns of photoselection in the product state dynamics are discussed in the light of recent theoretical developments incorporating electronic degrees of freedom in state-to-state photofragmentation.
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 5369-5379 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A simple theoretical model is developed for relative band intensities in multiresonant molecular three-photon ionization. A specific case is considered in which a dissociative system of states exists at the energy of the first photon and a discreet level system at the second. A third photon ionizes the molecule. Experimentally such a system shows non-Franck–Condon transitions with relative intensities that depend on laser power. Model calculations trace this dependence to the coherent preparation of a superposition state over the levels at the energy of the first photon that lie within the power-broadened bandwidth of the laser. For reasonable choice of field and molecule parameters, the model reproduces well the power-dependent band intensities reported in the previous paper for NO2.
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 5361-5368 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The two-photon absorption spectrum of the X 2A1→3pσ 2∑+u transition in NO2 shows prominent Franck–Condon forbidden origins. The absolute intensities of these non-Franck–Condon transitions, as seen by ionization, diminishes at high power. A dense system of dissociative states lies intermediate at the level of the first photon. These states are highly mixed in either bent or linear zeroth-order basis, and thus at low power effectively bridge bent-to-linear origins. At high laser intensity, power (lifetime) broadening prepares a superposition state with the optical character of the ground state and thus poor overlap with low-lying linear excited states. The preparation and projection of this zeroth-order, nonstationary intermediate state bears strong analogy to similar absorption and fluorescence processes stimulated by picosecond pulses.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 375-378 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two laser techniques are used to measure densities of mercury atoms in the three 63PJ states populated in the positive column of a narrow (13.7 mm diameter) low-pressure Hg-Ar dc discharge. Relative densities are obtained as a function of radial position using a saturated laser absorption technique, while on-axis absolute densities are measured using the hook method (an interferometric technique). Results are shown for two mercury vapor pressures and are compared with computer model predictions.
    Type of Medium: Electronic Resource
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  • 7
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 5259-5269 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two laser-based techniques are used to derive radial density distributions and absolute densities for the three 63PJ excited states of mercury in the positive column of a low-pressure Hg-Ar dc discharge. In the saturated laser absorption (SLA) method, a pulsed dye laser, traversing the discharge axially, is scanned through one of the 63PJ→73S1 transitions. At high laser powers the power absorbed from the beam on resonance approaches a constant saturated value directly proportional to the number density of Hg atoms in the 63PJ state selected. On-axis absolute density estimates and radial distribution results are presented for the three states at several discharge conditions. The hook method, a well-known interferometric technique, more accurately establishes the absolute densities on axis, and several off-axis measurements are compared with SLA results.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 5270-5279 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Radial variations of the Hg(63P0,1,2) densities are measured in a low-pressure Hg-Ar discharge and the results are compared with a model. The 34-mm-diam discharge tube is operated in the vicinity of 400-mA current, 6.4-mTorr Hg pressure, and 2.81-Torr Ar pressure. A tunable dye laser beam passes axially through the discharge tube, and densities are measured using both a saturated absorption technique and an interference technique. The model incorporates continuity equations for Hg excited and ionic states, and a two-temperature approach to parametrizing the electron energy distribution function. The shapes of the radial density distributions of the various species are predicted rather than assumed. Considerable attention is given to the role of tail electrons above the energy threshold for Hg inelastic scattering. Theoretical considerations and the measured variations of the 63P0 and 63P2 metastable densities suggest that the tail electron temperature is lower near the wall than at the center of the discharge.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 88 (1984), S. 1271-1273 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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