EPR Optical Detection of F Centre Pairs in Alkali Halides. II. Spin-Lattice Relaxation of the F Centre in Its Relaxed Excited State

✍ Scribed by Y. Ruedin; P.-A. Schnegg; C. Jaccard; M. A. Aegerter

• Publisher: John Wiley and Sons
• Year: 1973
• Tongue: English
• Weight: 492 KB
• Volume: 55
• Category: Article
• ISSN: 0370-1972
• DOI: 10.1002/pssb.2220550121

✦ Synopsis

Abstract

Like the EPR line of the fundamental state of the F centre in most of the alkali halide crystals, the line attributed to the relaxed excited state detected optically for F centre pairs is also Gaussian in shape. That is explained by an inhomogeneous broadening due to hyperfine interactions with the surrounding nuclei. The measurements of these resonances as a function of the microwave power allow to determine the saturation parameter and the broadening of the elementary line (homogeneous). On the other hand the measurement of the resonance signal as a function of temperature, the other parameters remaining constant, shows that it stays constant for T < 10 °K and decreases for increasing temperature. This is attributed to the spin‐lattice relaxation time T~1~ of the defect in its relaxed excited state. The relaxation mechanism is characterized by an Orbach process.