Photo-induced phenomena in GeO2 glass

Abstract

Photo-induced changes in GeO2 glass have been studied in optical and structural properties. Band-gap excitation gives rise to modifications in mid-gap optical absorption and photo-luminescence spectrum. It also produces electron-spin signals at g ≃ 1.995 and 2.008.Raman-scattering spectrum becomes sharper, x-ray diffraction patterns show disappearance of a crystalline peak, and illuminated surfaces expand. These observations can be accounted for by assuming bond transformations from rutile-like to defective quartz-like structures and/or from small to large rings. These photo-induced changes in GeO2 are comparatively discussed with those in SiO2 and GeS2.

The structure and optical properties of GeO2–GeS2 glasses

“…Optical transmission spectra were monitored using a double-beam spectrometer (JASCO, V-570 S), and absorption spectra were calculated following the conventional procedure [7]. The color changes from yellow and orange in GeS 2 to transparent in GeO 2 , which is consistent with reported optical gaps of 3.2 eV [7] and $5.8 eV [14,15], respectively. However, we see that even for a single composition, 30GeO 2 -70GeS 2 , there exist three kinds of samples that are yellow-, orange-, and brown-colored.…”

“…Fig. 7 compares absorption spectra of yellow GeS 2 , 30GeO 2 -70GeS 2 glasses of the three colors, and GeO 2 [14]. In the present study, we could obtain thick (0.5-1 cm) samples only for yellow GeS 2 and brown 30GeO 2 -70GeS 2 , for which the spectra could be evaluated at a P 2 cm À1 , where a is the absorption coefficient.…”

“…4. Differential RDFs of yellow GeS 2 (x = 0) and 30GeS 2 -70GeO 2 (yellow and brown), together with that in GeO 2 (x = 100) glass [14]. the latter is not clear, but micro-structures peculiar to the brown glass may be responsible.…”

“…[6], have been converted to differential RDF profiles, and some results are shown in Fig. 4, together with that in GeO 2 [14].…”

Photoinduced Electron Spin Resonance Phenomenon in α‐Cr2O3 Nanospheres

“…They have observed a strong second harmonic generation signal [49] originating from the 4 A 2g → 4 T 2g transition of Cr 3+ ions in -Cr 2 O 3 due to the two-photon excitation of 4 T 2g levels below N [48] and have been used to image the antiferromagnetic domains and determine magnetic symmetry. Likewise, it is noteworthy to highlight an analogous observed photoinduced effect by Terakado and Tanaka [50]. They have reported the first studies on photoinduced changes in GeO 2 glass system which has been investigated in terms of its optical and structural properties too.…”