Spectra of the selective heat radiation of Yb2O3 under the laser thermal excitation

The dependence of the spectra of the near-IR and visible selective heat radiation (SHR) of the Yb₂O₃ polycrystals that are synthesized using the laser thermal method on the excitation intensity of the CW electric discharge CO₂ laser at the wavelength λ = 10.6 μm is experimentally studied. The SHR spectra are determined by the multiphonon excitation of the vibronic states of the ² F _5/2 term in the Yb³⁺ ions and the radiative transitions to the vibronic states of the ground term ² F _7/2.The laser heating of the polycrystals to the melting point causes the anomalous growth of the SHR spectral peaks in the wavelength range λ ≥ 1040 nm due to an increase in the intensity related to an increase in the probabilities of the radiative vibronic transitions owing to the thermal increase in the phonon density. The effective conversion of the thermal energy of the Yb₂O₃ polycrystals into the SHR indicate the significant role of the radiative cooling of surface.