Analytical method for stable background reduction for Raman spectra of carbon‐containing meteorite and terrestrial samples suffering from intense fluorescence

Chemical states of carbon in terrestrial (meta) sediments and carbonaceous chondrites gather attention as a geothermometer. As a nondestructive analytical method, Raman spectroscopy has been widely used to study their electronic properties, crystallinity, and structural defects through so‐called D a...

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Bibliographic Details
Published in:Meteoritics & planetary science 2024-02, Vol.59 (2), p.338-350
Main Authors: Kashima, Aruto, Urashima, Shu‐hei, Yui, Hiroharu
Format: Article
Language:English
Subjects:
Analytical methods
Banded structure
Carbon
Carbonaceous chondrites
Chondrites
Crystal defects
Fluorescence
Geothermometers
Nondestructive testing
Polynomials
Raman spectra
Raman spectroscopy
Sediments
Spectroscopy
Spectrum analysis
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Summary:Chemical states of carbon in terrestrial (meta) sediments and carbonaceous chondrites gather attention as a geothermometer. As a nondestructive analytical method, Raman spectroscopy has been widely used to study their electronic properties, crystallinity, and structural defects through so‐called D and G bands. For the analysis of Raman spectra, a common problem is coexistence of a fluorescence background, which should be subtracted prior to the peak‐fitting analysis. However, we recently faced a problem that the band shape noticeably changed depending on the background function assumed although the background seemed to be well subtracted at a first glance regardless of the choice of the background function. For the application of the Raman spectroscopy as a geothermometer, a standard background subtraction method must be established to suppress the arbitrariness. In the present study, Raman spectra of seven carbon‐containing natural samples, whose background intensities were significantly different, were measured, and their background shape was evaluated by first‐, second‐, and third‐order polynomials. The results indicated that the third‐order polynomial was necessary and sufficient as a standard background function. Importantly, although lower order polynomials seem to successfully fit the background at a first glance, they falsely caused dispersion of the shoulder band shape.
ISSN:1086-9379
1945-5100
DOI:10.1111/maps.14123