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  • 1995-1999  (5)
  • 1975-1979
  • 1955-1959
  • 1945-1949
  • 1997  (5)
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  • 1995-1999  (5)
  • 1975-1979
  • 1955-1959
  • 1945-1949
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  • 1
    Electronic Resource
    Electronic Resource
    Aligning symmetric and asymmetric top molecules via single photon excitation (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 7138-7147 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The theory developed by Zare [Ber. Bunsenges. Phys. Chem. 86, 422 (1982)] for using electric-dipole-allowed photoexcitation with linearly polarized light to align linear and symmetric top molecules via parallel transitions is extended to include perpendicular transitions, as well as the alignment of asymmetric tops via a-, b-, or c-type transitions. Analytical expressions for the spatial distribution of a symmetric top figure axis following a parallel or perpendicular transition are presented. A prescription is developed for determining the spatial distribution of each principal axis of an asymmetric or symmetric top following parallel or perpendicular type transitions. The degree of alignment obtainable via photoexcitation for symmetric and asymmetric tops is discussed, with the somewhat surprising result that all three principal axes of an asymmetric top can be highly aligned via photoexcitation. A simple computer program for calculating the degree of alignment of each principal axis of a symmetric or asymmetric top following an a-, b-, or c-type transition is described and made available. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474955
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    High resolution mid-infrared spectroscopy of ArH2O: The v2 bend region of H2O (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 3078-3089 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Six internal rotation/vibration bands of ArH2O are observed in a slit supersonic expansion via direct absorption of a tunable diode laser in the v2 bend region of H2O. The spectra obtained for the ortho H2O manifold are well represented by a pseudodiatomic model with nearly free internal rotation of the H2O subunit. By way of contrast, the para bands show significant mixing between the internal rotor and stretch states, indicative of strong angular-radial coupling in the intermolecular potential. The spectra for the para Ar–H2O species can be deperturbed based on a three state Coriolis plus angular-radial coupling model which includes microwave, far-ir and near-ir data. The results indicate a redshift of (approximate)0.58 cm−1 upon bend excitation of the H2O subunit, and in general rather modest changes in the excited state intermolecular potential from the ground state potential. No indication of predissociation broadening is found, and the instrument-limited linewidths place a lower limit on the vibrational lifetime in the excited state of τ≥7.2(6) ns. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473051
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Scattering dynamics in HF+He, Ne, and Ar: State-to-state cross sections, Dopplerimetry, and alignment measurement via direct infrared laser absorption in crossed supersonic jets (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 2248-2264 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Absolute state-to-state cross sections are reported for rotationally inelastic scattering in crossed jets of HF with He, Ne, and Ar at mean center-of-mass collision energies of 480, 390, and 350 cm−1, respectively. HF seeded in Ar diluent gas is cooled into the J=0 ground rotational state in a pulsed supersonic expansion, followed by single collision rotational excitation with rare gas atoms from a second pulsed supersonic jet. The column-integrated densities of HF in both the initial and final scattering states are probed in the jet intersection region via direct absorption of light from a narrow bandwidth (0.0001 cm−1), continuously tunable, color center laser. Total inelastic cross sections for collisional loss out of J=0 and collisional excitation into J〉0 states are determined in absolute units from the dependence of infrared absorption signals on collider gas concentration. Full close coupling scattering calculations are performed on several ab initio and empirical potential energy surfaces for each of the three HF+rare gas systems. Agreement for He+HF and Ar+HF integral cross sections is remarkably good, but significant discrepancies are noted for the less accurately determined Ne+HF surface. Photoelastic polarization modulation of the IR laser is used to probe for rotational alignment in the scattered HF flux; the measurements set an upper polarizance limit for collisionally populated J=1 HF molecules [probed on P(1)] of |P|〈2%. High resolution IR laser Dopplerimetry reveals velocity structure in the collisionally excited J=1 Doppler profiles, which is in excellent qualitative agreement with theoretical predictions of rainbow features in the J=1←0 state-to-state differential cross section. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473787
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Psychological morbidity and coping skills in patients with brittle and non-brittle asthma: a case-control study (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 27 (1997), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background An association between psychological morbidity and asthma is well recognized and an increase in negative psychosocial factors in brittle asthma has been previously reported. Stich factors, apart from affecting patient perceptions, may alter patients’ self-management of their condition.Methods We have undertaken a case-control study on 29 well characterized brittle and non-brittle asthmatics in the West Midlands Region to assess their level of psychological morbidity, using the General Health Questionnaire (GHQ) and the living with asthma questionnaire, and their responses to changes in asthma symptoms, using the Asthma Symptom Checklist and a taped interview.Results Significant differences in GHQ (mean score brittle 19.5 vs non-brittle 7.2, P = 0.0002) and living with asthma (mean score brittle 1.30 vs non-brittle 1.00, P = 0.002) reinforced the presence of psychological factors in this group of patients with severe asthma. Interviews regarding responses to hypothetical asthma attacks showed that patients with brittle asthma delayed seeking medical attention more often than those with non-brittle asthma and instead preferred to self-administer beta-agonist medication. Sixteen (55.2%) of the 29 patients with brittle asthma would have delayed 7 days before seeking medical attention in a slow onset attack compared with 6/29 (20.7%) in the non-brittle group. In a fast onset attack 14 (48.3%) patients with brittle asthma would not have summoned help, despite finding it difficult to walk to the kitchen for a drink whereas in the non-brittle group 24 out of 29 (82.8%) would have summoned help. Levels of family support tended to be lower in patients with brittle asthma (mean family APGAR 7.3 vs 8.65 P = 0.09).Conclusions Brittle asthma is associated with greater psychological morbidity and altered strategies for coping with deteriorating asthma symptoms. Attention should be paid to the presence of such factors in the management of patients with brittle asthma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2222.1997.1080961.x
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  • 5
    Electronic Resource
    Electronic Resource
    Image enhancement and stress separation of thermoelastically measured data under random loading (1997)
    Springer
    Experimental mechanics 37 (1997), S. 225-231 
    Details
    ISSN: 1741-2765
    Keywords: Thermoelastic ; hybrid ; stress ; random ; thermography ; infrared stress analysis ; thermographic stress analysis ; thermal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Traditional thermoelastic stress analysis (TSA) presupposes that the structure being analyzed is cyclically loaded at a constant amplitude and frequency. This approach typically has been used to satisfy the adiabatic reversible assumptions. The authors employ an alternative signal analysis technique that enables one to evaluate the magnitude of the individual components of stress in a component subjected to a loading that is random in both frequency and magnitude. However, the nature of the measured information does not change; i.e., data are inherently noisy, and edge information is unreliable. The latter two aspects have caused many thermoelastic stress analyses to be more qualitative than quantitative. The present paper emphasizes developing the TSA technique into a practical, noncontacting quantitative method for stress analyzing actual engineering structures that are randomly loaded. In particular, ability to determine the individual stresses thermoelastically under random loading is demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02317411
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