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Electrostrictive laser-induced gratings for time-resolved observation of translational-rotational energy transfer in H2

Hubschmid, W. ; Bombach, R.

In: Applied Physics B, 2011, vol. 103, no. 4, p. 933-939

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    Titre
    • Electrostrictive laser-induced gratings for time-resolved observation of translational-rotational energy transfer in H2
    Auteur
    • Hubschmid, W.. Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
    • Bombach, R.. Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
    Type de document
    • Postprint
    Classification
    • Physique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:318215
    Summary
    Electrostrictive laser-induced gratings (LIG) have been formed in H2 of various pressures (0.5 5 bar) and with frequencies of the Brillouin modes (sound waves) of about 14 MHz. Under these conditions, the rotational degrees of freedom can only partially follow the temperature variation from the acoustic oscillation. A model is given, which completes the linearized fluid dynamical equations with equations for the rotational state relaxation, separately for the average relaxation of the states for Ortho-H2 and Para-H2. Using such a model, the dispersion of sound frequency is reproduced with an accuracy of a few percent. However, the total dissipation of sound and the observed strong alternation in peak heights in the temporal evolution of the LIG intensity is only approximately predicted by the model