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Long-Time Relaxation of Stress-Induced Birefringence of Microcrystalline Alkali Halide Crystals

Alkali halide single crystals are most commonly used as the diluent matrix in the tablet method or disk technique for spectroscopic measurements. However, stress-induced birefringence (SIB) of alkali halides as well as intrinsic birefringence manifest during the disk formation process. Thus, the tru...

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Autores principales: Ueno, Hiroki, Arakane, Ryoga, Matsumoto, Yoshihisa, Tsumura, Tomoki, Kitazaki, Akihito, Takahashi, Toru, Hirao, Shotaro, Ohga, Yasushi, Harada, Takunori
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6017667/
https://www.ncbi.nlm.nih.gov/pubmed/29587395
http://dx.doi.org/10.3390/molecules23040757
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author Ueno, Hiroki
Arakane, Ryoga
Matsumoto, Yoshihisa
Tsumura, Tomoki
Kitazaki, Akihito
Takahashi, Toru
Hirao, Shotaro
Ohga, Yasushi
Harada, Takunori
author_facet Ueno, Hiroki
Arakane, Ryoga
Matsumoto, Yoshihisa
Tsumura, Tomoki
Kitazaki, Akihito
Takahashi, Toru
Hirao, Shotaro
Ohga, Yasushi
Harada, Takunori
author_sort Ueno, Hiroki
collection PubMed
description Alkali halide single crystals are most commonly used as the diluent matrix in the tablet method or disk technique for spectroscopic measurements. However, stress-induced birefringence (SIB) of alkali halides as well as intrinsic birefringence manifest during the disk formation process. Thus, the true chiroptical measurement is disturbed by optical anisotropies (OA) containing SIB and intrinsic birefringence, except in the case of optical homogeneity. SIB is generally larger than intrinsic birefringence and has a value of several thousand millidegrees in the ultraviolet-visible wavelength range, although this varies with disk type. Here, to investigate the SIB origin, alkali halide crystals were examined using polarized light, X-ray diffraction, Fourier-transform infrared, and electron backscattering diffraction spectroscopic measurements. It was found that, after stress release, the SIB exhibited nonlinear long-time relaxation, which roughly converged within several hours, with the only time-invariant intrinsic birefringence remaining being due to OA. This behavior was strongly related to an increase in the quasi-amorphous domain and the generation of an air gap between the crystallite boundaries and their pellets. Further, a straightforward correlation was found between amorphization and an increase in the disk water content caused by deliquescence. Thus, the OA of alkali halide single crystals was found to have two different origins yielding intrinsic birefringence and SIB.
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spelling pubmed-60176672018-11-13 Long-Time Relaxation of Stress-Induced Birefringence of Microcrystalline Alkali Halide Crystals Ueno, Hiroki Arakane, Ryoga Matsumoto, Yoshihisa Tsumura, Tomoki Kitazaki, Akihito Takahashi, Toru Hirao, Shotaro Ohga, Yasushi Harada, Takunori Molecules Article Alkali halide single crystals are most commonly used as the diluent matrix in the tablet method or disk technique for spectroscopic measurements. However, stress-induced birefringence (SIB) of alkali halides as well as intrinsic birefringence manifest during the disk formation process. Thus, the true chiroptical measurement is disturbed by optical anisotropies (OA) containing SIB and intrinsic birefringence, except in the case of optical homogeneity. SIB is generally larger than intrinsic birefringence and has a value of several thousand millidegrees in the ultraviolet-visible wavelength range, although this varies with disk type. Here, to investigate the SIB origin, alkali halide crystals were examined using polarized light, X-ray diffraction, Fourier-transform infrared, and electron backscattering diffraction spectroscopic measurements. It was found that, after stress release, the SIB exhibited nonlinear long-time relaxation, which roughly converged within several hours, with the only time-invariant intrinsic birefringence remaining being due to OA. This behavior was strongly related to an increase in the quasi-amorphous domain and the generation of an air gap between the crystallite boundaries and their pellets. Further, a straightforward correlation was found between amorphization and an increase in the disk water content caused by deliquescence. Thus, the OA of alkali halide single crystals was found to have two different origins yielding intrinsic birefringence and SIB. MDPI 2018-03-25 /pmc/articles/PMC6017667/ /pubmed/29587395 http://dx.doi.org/10.3390/molecules23040757 Text en © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Ueno, Hiroki
Arakane, Ryoga
Matsumoto, Yoshihisa
Tsumura, Tomoki
Kitazaki, Akihito
Takahashi, Toru
Hirao, Shotaro
Ohga, Yasushi
Harada, Takunori
Long-Time Relaxation of Stress-Induced Birefringence of Microcrystalline Alkali Halide Crystals
title Long-Time Relaxation of Stress-Induced Birefringence of Microcrystalline Alkali Halide Crystals
title_full Long-Time Relaxation of Stress-Induced Birefringence of Microcrystalline Alkali Halide Crystals
title_fullStr Long-Time Relaxation of Stress-Induced Birefringence of Microcrystalline Alkali Halide Crystals
title_full_unstemmed Long-Time Relaxation of Stress-Induced Birefringence of Microcrystalline Alkali Halide Crystals
title_short Long-Time Relaxation of Stress-Induced Birefringence of Microcrystalline Alkali Halide Crystals
title_sort long-time relaxation of stress-induced birefringence of microcrystalline alkali halide crystals
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6017667/
https://www.ncbi.nlm.nih.gov/pubmed/29587395
http://dx.doi.org/10.3390/molecules23040757
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