Luminescence and Raman Detection of Molecular Cl2 and ClClO Molecules in Amorphous SiO2 Matrix

Abstract Image

Chlorine is a common undesirable impurity in synthetic SiO2 glass for ultraviolet optics and optical fibers. It is usually incorporated into glass as bound Si–Cl groups or interstitial Cl2molecules. We report a high-sensitivity detection of Cl2 in amorphous SiO2 (a-SiO2) by photoluminescence (PL) and also by Raman spectroscopy. The Cl2 PL emission band at 1.22 eV (1016 nm) appears at T < 160 K and shows a characteristic vibronic progression with separations ≈(520–540) cm–1 and an average lifetime of ≈5 ms at 13 K. Its excitation spectrum coincides with the shape of the 3.78 eV (328 nm) optical absorption band of Cl2 in a-SiO2, corresponding to the X → A 1Πu transition to repulsive excited state. Direct X → a singlet-to-triplet excitation was also observed at 2.33 eV (532 nm). Cl2 PL may serve as a sensitive and selective tool for monitoring Cl impurities and their reactions in a-SiO2. A Raman band of Cl2 is found at 546 cm–1. Cl2 photodissociation at energies up to 4.66 eV (266 nm) was not detected, pointing to a strong cage effect in a-SiO2 matrix. However, 7.9 eV (157 nm) photolysis of interstitial O2molecules gives rise to a Raman band at 954 cm–1, indicating a formation of dichlorine monoxide isomer, ClClO molecule by reaction of O atoms with interstitial Cl2.

J. Phys. Chem. C, 2017, 121 (9), pp 5261–5266

pdf-icon Download PDF

Raman, electron microscopy and electrical transport studies of x-ray amorphous Zn-Ir-O thin lms deposited by reactive DC magnetron sputtering

M. Zubkins, R. Kalendarev, J. Gabrusenoks, K. Smits, K. Kundzins,
K. Vilnis, A. Azens, J. Purans

Abstract. Zn-Ir-O thin lms on glass and Ti substrates were deposited by reactive DC
magnetron sputtering at room temperature. Structural and electrical properties were
investigated as a function of iridium concentration in the lms. Raman spectrum of Zn-Ir-
O (61.5 at.% Ir) resembles the spectrum of rutile IrO2, without any distinct features of wurtzite
ZnO structure. SEM images indicated that morphology of the lms surface improves with
the iridium content. EDX spectroscopy and cross-section SEM images revealed that the lms
growing process is homogeneous. Crystallites with approximately 2 – 5 nm size were discovered
in the TEM images. Thermally activated conductivity related to the variable range hopping
changes to the non-thermally activated before iridium concentration reaches the 45 at.%.

IOP Conference Series: Materials Science and Engineering 77 (2015) 012035


pdf-iconDownload PDF