Terahertz Time-Domain Spectroscopy of Glasses

Sundaram, S. K. "Terahertz Time-Domain Spectroscopy of Glasses." In Springer Handbook of Glass, pp. 909-929. Springer, Cham, 2019.

Abstract

Terahertz-time domain spectroscopy () uses the real and imaginary parts of the dielectric and optical constants for glass characterization over a wide frequency range in the electromagnetic spectrum. This chapter provides an overview and analysis of various THz spectrometers and typical data sets over 0.1−10THz$0.1-10\mathrm{T}\mathrm{H}\mathrm{z}$. Phonon modes in THz region and Lunkenheimer–Loidl plots for disordered materials along with density-functional based tight-binding () modeling results for As2S3$\mathrm{A}{\mathrm{s}}_2{\mathrm{S}}_3$ are described. THz optical and dielectric properties of selected model glass systems, e. g., silica, alkali borate, and silicates, based on works reported in the literature, are discussed. Mixed-alkali effects and thermal stability in terms of THz properties of simple tellurite glass composition, 80TeO2$80\mathrm{T}\mathrm{e}{\mathrm{O}}_2$-10WO3$10\mathrm{W}{\mathrm{O}}_3$-(10−x$10-x$)Li2O$\mathrm{L}{\mathrm{i}}_2\mathrm{O}$-xNa2O$\mathit{x}\mathrm{N}{\mathrm{a}}_2\mathrm{O}$ with x=$x=$ 0, 2, 4, and 6, are reported. Chalcogenide (As-S) glasses show that the refractive indices in THz, infrared, and visible frequencies decrease with arsenic composition up to a point of optimal constrained structure with average coordination number, ⟨r⟩$⟨r⟩$, beyond which the refractive index increases. Our results in hydroxyapatite (Ca10(PO4)6$\mathrm{C}{\mathrm{a}}_{10}(\mathrm{P}{\mathrm{O}}_4{)}_6$⋅$\cdot$(OH)2$(\mathrm{O}\mathrm{H}{)}_2$; HA)-glass (0.05CaO-0.12TiO2$0.12\mathrm{T}\mathrm{i}{\mathrm{O}}_2$-0.17Na2O$0.17\mathrm{N}{\mathrm{a}}_2\mathrm{O}$-0.28ZnO-0.38SiO2$0.38\mathrm{S}\mathrm{i}{\mathrm{O}}_2$) composites demonstrate that the THz-TDS can be a promising non-destructive tool for evaluating these composites and tracking their degradation in simulated body fluids in biological applications.

for full paper see https://link.springer.com/chapter/10.1007/978-3-319-93728-1_26