Thermal bleaching of V bands at room temperature in alkali iodide crystals containing excess iodine

• Published in: Journal of the Physical Society of Japan 2003-06, Vol.72 (6), p.1570-1573
• Main Authors: HARAMI, Tadahiko, KATAOKA, Mariko
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity); Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Physics
• ISSN: 0031-9015; 1347-4073
• DOI: 10.1143/JPSJ.72.1570

Thermal stability of V centers has been investigated at room temperature (RT) for additively colored alkali-iodide crystals by means of optical absorption measurements. V2 and V3 bands due to V centers in the crystal were gradually bleached by annealing at temperatures near RT. The bleaching rate of the bands is proportional to the square of the V-center concentration. The activation energies for bleaching of the V bands in KI and RbI crystals are estimated from the bleaching rates to be 0.85±0.04 eV and 0.82±0.03 eV, respectively. The V2 bands in the crystals containing divalent cations bleach only weakly at RT. The effect of impurities, such as divalent cations, on the thermal stability of the V centers will be discussed.