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  • 1
    Electronic Resource
    Electronic Resource
    Rotationally inelastic rates for N2–N2 system from a scaling theoretical analysis of the stimulated Raman Q branch (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 5568-5577 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Self-broadened nitrogen isotropic Q(J) Raman linewidths have been inverted to obtain effective rotation–translation (R–T) state-to-state rate constants using the energy corrected sudden (ECS) formalism. These rate constants are discussed as a function of the rotational levels J and temperature T. Collisional Q(J) line shifts have been investigated by high-resolution inverse Raman spectroscopy (IRS) over a wide temperature range. Semiclassical calculations lead to a clear understanding of their J and T dependence. This exhaustive study of both diagonal and off-diagonal relaxation matrix elements has allowed us to calculate the collisionally narrowed Q branch at high pressure. New measurements of N2 Q branch at high pressure have been performed by IRS. The good agreement of ECS profiles with IRS data, for various pressures and temperatures, underlines the consistency of the present R–T ECS scaling analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455563
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  • 2
    Electronic Resource
    Electronic Resource
    Line broadening, line shifting, and line coupling effects on N2–H2O stimulated Raman spectra (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 5916-5925 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In order to understand the influence of H2O on the stimulated Raman Q-branch spectra of nitrogen in combusting media, an exhaustive theoretical and experimental study has been carried out. Starting from a semiclassical model, particularly convenient at high temperature, the Q-line broadening and shifting coefficients have been calculated over a wide temperature range and for a large number of lines. Stimulated Raman Spectra (SRS) measurements have allowed us to test these calculated line broadening coefficients and thus establish the high accuracy of semiclassical values. The theoretical broadening coefficients have been inverted to deduce state-to-state rotational relaxation rates by using two types of fitting laws. A partial test of the resulting Q-branch profiles has been realized at moderate pressures leading to a discrimination between these two laws. Furthermore, the effect of rotational energy transfers on collisionally narrowed profiles at higher densities has been simulated and compared with the pure N2 case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457461
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  • 3
    Electronic Resource
    Electronic Resource
    Speed-dependent line profile: A test of a unified model from the Doppler to the collisional regime for molecule–molecule collisions (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 4951-4956 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A speed-dependent line profile combining soft and hard fully correlated Dicke-narrowing collisions was recently successfully tested on Ar-broadened H2 spectra in a wide density and temperature range. A further test for mixtures of H2 in nitrogen molecules (instead of Ar atoms) is presented. This test is also based on high resolution Raman investigation of the isotropic Q(1) line of H2 from low to high density at various temperatures. The same consistency of the speed-dependent line profile as for H2–Ar is obtained for H2–N2 through a remarkable agreement with all the data by using a unique set of four parameters (the collisional width and shift, the kinetic frequency, and a characteristic velocity memory parameter). The present study is a preliminary step for the hydrogen CARS thermometry in H2–air flames at high pressure. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1287824
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  • 4
    Electronic Resource
    Electronic Resource
    Collisional effects on spectral line shape from the Doppler to the collisional regime: A rigorous test of a unified model (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 158-166 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The paper presents high resolution Raman investigations of the Q(1) line of H2 in Ar mixture from low density (Doppler regime) to high density (collisional regime) analyzed with a unique line shape profile. Measurements are performed by stimulated Raman gain spectroscopy between 300 and 1000 K in a wide density range (from 0.2 to 11 amagat). All the observed spectral features are accurately described by a unified model recently proposed by two of the authors. This model accounts for a velocity-memory process, not restricted to the usual hard and soft limits. It also includes correlation between velocity- and phase-changing collisions. An exhaustive analysis of various possible mechanisms on the line shape is achieved. These mechanisms are the Dicke narrowing, the radiator speed dependence of the collisional broadening and shifting parameters, the collisionally induced speed-class exchange and the nonimpact effect. The present test shows the high consistency of the unified model, since it allows one to get a remarkable agreement with all the data by using a unique set of parameters. This model should be useful for optical diagnostics at moderate density, as required for combusting media or atmospheric work. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480570
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  • 5
    Electronic Resource
    Electronic Resource
    Systematic errors in precision lattice-parameter determination of single crystals caused by asymmetric line profiles (1986)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 19 (1986), S. 34-38 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The convolution of the various contributions to X-ray intensity distribution curves measured in lattice-parameter determination leads to peak shifts and, hence, to systematic errors in the case that at least one of the contributing curves is asymmetric. For perfect crystals, depending on the collimator divergence, this effect may reach the order of magnitude of the refraction correction. It is caused by the asymmetry of the spectral distribution curve, which includes intrinsic asymmetry, dispersion and angle dependence of intensity (ADI). For imperfect crystals characterized by orientation and interplanar-spacing distributions, the distribution curves should be measured in order to correct accurately the peak shift. Examples of simulation calculations are given for Si, Cu Kα1, Bond method for various reflections of perfect crystals and for crystals having orientation distributions, 444 reflection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889886090039
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  • 6
    Electronic Resource
    Electronic Resource
    A method for precision lattice-parameter measurement of single crystals. Erratum (1985)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 18 (1985), S. 365-365 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: In the paper by Berger [J. Appl. Cryst. (1984), 17, 451–455] two errors have occurred. The formulae for the vertical divergence error Δθd on page 453, left-hand column, should read: \Delta \theta _{d} = {{1}\over{2}} {\rm tan} \theta {{ \int\limits^F_{-F} \int\limits^P_{-P} \delta ^{2}{\rm d}p {\rm d}f}\over{\int\limits^F _{-F} \int\limits^P_{-P} {\rm d}p {\rm d}f}}with \delta = (p - f)/s,and thus \Delta \theta _{d} = {{1}\over{6}} {\rm tan} \theta(P^{2} + F^{2})/s^{2}. \eqno (3)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889885010470
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  • 7
    Electronic Resource
    Electronic Resource
    Gefäßchirurgie – Quo vadis? (2000)
    Springer
    Gefässchirurgie 5 (2000), S. 1-3 
    Details
    ISSN: 1434-3932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010569
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  • 8
    Electronic Resource
    Electronic Resource
    Optical properties of the quasi-two-dimensional dichalcogenides 2H-TaSe and 2H-NbSe (2003)
    Springer
    The European physical journal 33 (2003), S. 15-23 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 78.20.-e Optical properties of bulk materials and thin films – 71.45.Lr Charge-density-wave systems – 74.25.Gz Optical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: We present a comprehensive analysis of the optical constants of the two-dimensional dichalcogenide materials 2 H - TaSe 2 and 2 H - NbSe 2 , in an attempt to address the physics of two-dimensional correlated systems. The title compounds were studied over several decades in frequency, from the far-infrared to the ultraviolet. Measurements with linearly polarized light have allowed us to obtain both the in-plane and out-of-plane components of the conductivity tensor. Although the electromagnetic response of dichalcogenides is strongly anisotropic, both the in-plane and out-of-plane components of the conductivity tensor share many common features, including the presence of a well-defined metallic component, as well as a “mid-infrared band”. We discuss the implications of these results in the context of the spectroscopic results of other classes of low-dimensional conductors such as the high-temperature superconducting cuprates. In particular, the analysis of the redistribution of the spectral weight as a function of temperature, as well as the behavior of the quasiparticles relaxation rate, points to significant distinctions between the charge dynamics of dichalcogenides and other classes of low dimensional conductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2003-00136-1
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  • 9
    Electronic Resource
    Electronic Resource
    Specific heats of the charge density wave compounds o-TaS and (TaSe ) I (2002)
    Springer
    The European physical journal 29 (2002), S. 71-77 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 71.45.Lr Charge-density-wave systems – 65.40.Ba Heat capacity – 64.70.Kb Solid solid transitions – 64.70.Pf Glass transitions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Specific heats of the charge-density-wave compounds o-TaS3 and (TaSe4)2I have been measured over the wide temperature interval 10 K-300 K. Both systems exhibit strong non-Debye behavior. Very weak and broad anomalies are observed at the Peierls transition temperatures. For o-TaS3, the change in the curvature of the specific heat occurs at temperature of 40 K where glass transition has been deduced from dielectric measurements, and an extended scaling analysis suggests that the glass transition is associated with a dynamical cross over in length scales. We briefly discuss the characteristics and physical origins of the anomalies at both the Peierls and glass transitions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2002-00263-1
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  • 10
    Electronic Resource
    Electronic Resource
    Infrared spectroscopy of tetrahedral quantum spin systems Cu $\mathsf{_2}$ Te $\mathsf{_2}$ O $\mathsf{_5}$ X $\mathsf{_2}$ (X = Br and Cl) (2004)
    Springer
    The European physical journal 38 (2004), S. 65-70 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Cu2Te2O5X2, with X = Br and Cl, are spin-tetrahedral systems displaying magnetic ordering at low temperatures. We have performed optical reflectivity measurements over a broad spectral range as a function of temperature and magnetic field. We have identified the resonance frequencies of the infrared optically active phonon modes and estimated the value of the electronic gap in both tellurate compounds. No variation of the spectra has been observed while crossing the magnetic ordering transition temperature or by applying a magnetic field. The implications of these findings are discussed in relation to the nature of the phase transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2004-00100-7
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