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Get to Know Metrohm


Titration


Raman shift(cm-1


)


Figure 3 – Raman spectra of diamond, moissanite, and quartz measured on inVia confocal Raman microscope from Renishaw (West Dundee, IL). (© Copyright Renishaw plc. All rights reserved. Image reproduced with permission of Renishaw.)


Electrochemistry


Ion Chromatography


Spectroscopy


Laboratory


Process


Find out more at www.metrohmusa.com/technology


Figure 4 – Spectral differences between natural red coral and dyed coral. The spectral peaks for red coral are 1129 cm-1 1089 cm-1


and 1517 cm-1 ; for dyed coral there is a single, high-intensity spectrum at


(© Copyright Gem Testing Laboratory, Jaipur. All rights reserved. Image reproduced with permission of Gem Testing Laboratory, Jaipur.)


gemstone based on the Raman spectral ID com- parison to the library spectra for gemstones from various sources. A Raman spectrom- eter produces precise and distinctive spectra for all classes of minerals containing borates, carbonates, halides, native elements, oxides, phosphates, silicates, sulfates, and sulfides.


As shown in Figure 1, diamond has a carbon– carbon vibration Raman spectrum showing a single Raman shift at 1332 cm-1


, which confirms


the authenticity of pure diamond. Silicon wafer has a signature Raman shift at 520 cm-1 Raman shift at 300 cm-1 is a germanium.


. The indicates the gemstone AMERICAN LABORATORY 33 JUNE/JULY 2017 www.metrohm.com


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