Raman spectroscopy is a powerful tool for the analysis of vibrational and rotational modes of molecules, gases, liquids and solids. Nonetheless the architecture of Raman spectrometers can be used also for the collection of photoluminescence spectra which, in turn, are related to electronic transitions. Although Raman spectroscopists usually consider luminescence as a spurious artefact, in specific cases these unwanted signals may give valuable information about the system under study. Here I discuss how we have discovered, by using a Raman spectrometer, a new optically active defect in natural diamonds underwent to artificial treatment -exposure to ionizing radiation and thermal treatments- for colour enhancing. This spectroscopic indicator consists in narrow photoluminescence lines in the red region, between 681 and 725 nm, resulting from vacancies trapped by interstitial carbon aggregates and platelets. The discovery was statistically validated on a set of about one hundred samples. Beyond the physical description of the defect, I will show the different steps that brought us to the writing of two related patents for the construction of a device able to discern natural from treated diamonds, the realization of a feasibility study based on a bench prototype and to the subsequent pre-industrialization process

Lorenzi, R. (2018). Identification of a new defect in diamonds: application of Raman spectrometers beyond Raman scattering. Intervento presentato a: Raman Workshop, Zurich, Swiss.

Identification of a new defect in diamonds: application of Raman spectrometers beyond Raman scattering

Lorenzi
2018

Abstract

Raman spectroscopy is a powerful tool for the analysis of vibrational and rotational modes of molecules, gases, liquids and solids. Nonetheless the architecture of Raman spectrometers can be used also for the collection of photoluminescence spectra which, in turn, are related to electronic transitions. Although Raman spectroscopists usually consider luminescence as a spurious artefact, in specific cases these unwanted signals may give valuable information about the system under study. Here I discuss how we have discovered, by using a Raman spectrometer, a new optically active defect in natural diamonds underwent to artificial treatment -exposure to ionizing radiation and thermal treatments- for colour enhancing. This spectroscopic indicator consists in narrow photoluminescence lines in the red region, between 681 and 725 nm, resulting from vacancies trapped by interstitial carbon aggregates and platelets. The discovery was statistically validated on a set of about one hundred samples. Beyond the physical description of the defect, I will show the different steps that brought us to the writing of two related patents for the construction of a device able to discern natural from treated diamonds, the realization of a feasibility study based on a bench prototype and to the subsequent pre-industrialization process
abstract + slide
diamond, Raman, photoluminescence
English
Raman Workshop
2018
2018
none
Lorenzi, R. (2018). Identification of a new defect in diamonds: application of Raman spectrometers beyond Raman scattering. Intervento presentato a: Raman Workshop, Zurich, Swiss.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/214155
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