Temperature of the gas phase in solar processes from simulation of the YO fluorescence spectra for A²Π_1/2-X²Σ⁺, A²Π_3/2-X²Σ⁺, B²Σ⁺-X²Σ⁺ systems

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

Corresponding author: granier@promes.cnrs.fr

Received: 11 October 2004
Revised: 17 March 2005
Accepted: 17 May 2005
Published online: 25 October 2005

Abstract

We estimated the temperature of the gas phase surrounding a Y₂O₃ sample melted at the focus of a solar furnace by comparing the fluorescence spectra of YO molecule A²Π_1/2-X²Σ⁺, A²Π_3/2-X²Σ⁺, B²Σ⁺-X²Σ⁺ systems and simulated spectra (two temperature model). If A_3/2 and B systems can be described by a simple formulation for the calculation of upper and lower states energies, we have had, despite the poor resolution of our instrument, to use a full formulation and particularly introduce the Λ doubling terms, to satisfactorily describe the A_1/2 system. At low pressure the discrepancies between rotational and vibrational temperatures and the weakness of the fits suggest that the populations of internal levels do not follow Boltzmann distributions mainly close to the vaporizing surface. The temperatures determined at higher pressures (50 hPa) on the three systems are consistent each others and supposed representative of that of the gas phase.