Measurements of vibrational and rotational temperatures of YO molecule by emission and absorption spectroscopy in a solar process

Evidence of a non-equilibrium situation near the vaporizing surface

PROMES-CNRS, Procédés Matériaux et Énergie Solaire, BP 5, 66125 Font-Romeu, France

Corresponding author: granier@promes.cnrs.fr

Received: 9 February 2006
Accepted: 27 February 2007
Published online: 21 March 2007

Abstract

We measure by fluorescence emission and absorption spectroscopy rotational and vibrational temperature of YO molecule issuing from a liquid drop of Y₂O₃ melted at the focus of a solar furnace. Far from the surface and at high pressure these measurements are consistent with the predictions from a fluid dynamic calculation and are believed to give an approximate temperature of the gas phase surrounding the sample. Close to the surface and at low pressure these measurements disagree with the expected surface temperature. This results from the existence of a Knudsen layer near the vaporizing surface that, in these conditions and at our spatial resolution, we can explore, revealing according the gas pressure, quasi equilibrium or non-equilibrium conditions.