Raman spectroscopy of laser‐induced oxidation of titanomagnetites

Abstract

Titanomagnetites are important carriers of magnetic remanence in nature and can track redox conditions in magma. The titanium concentration in magnetite bears heavily on its magnetic properties, such as saturation moment and Curie temperature. On land and in the deep ocean, however, these minerals are prone to alteration which can mask the primary magnetic signals they once recorded. Thus, it is essential to characterize the cation composition and oxidation state of titanomagnetites that record the paleomagnetic field. Raman spectroscopy provides a unique tool for both purposes. Nonetheless, the heat generated by the excitation laser can itself induce oxidation. We show that the laser power threshold to produce oxidation decreases with increasing titanium content. With confocal Raman spectroscopy and magnetic force microscopy (MFM) on natural and synthetic titanomagnetites, a non-destructive Raman imaging protocol was established. We applied this protocol to map out the composition and magnetization state within a single ex-solved titanomagnetite grain in a deep-sea basalt.

Ag nanoparticles-based antimicrobial polycotton fabrics to prevent the transmission and spread of SARS-CoV-2

“…It is observed in 1613 cm -1 the mode referring to the stretching of the C 1 -C 4 carbon of the aromatic polyester ring, as well as its CH stretching in 3078 cm -1 . [41,42] It is also possible to observe in 1730 cm -1 the stretching of the C=O bonds of the esters and the stretching of the CH bonds of the methyl groups external to the ring, in 2975 cm -1 . [41][42][43] It is observed that the addition of Ag-based antimicrobials do not cause significant changes in the polycotton structure at short-range.…”

“…[41,42] It is also possible to observe in 1730 cm -1 the stretching of the C=O bonds of the esters and the stretching of the CH bonds of the methyl groups external to the ring, in 2975 cm -1 . [41][42][43] It is observed that the addition of Ag-based antimicrobials do not cause significant changes in the polycotton structure at short-range. As a complementary analysis to micro Raman spectroscopy, FTIR measurements were performed to investigate the functional groups of products after the incorporation of the two Ag-based antimicrobial solutions into the polycotton ( Figure 2).…”

Tribochemistry of Carbon Films in Oxygen and Humid Environments: Oxidative Wear and Galvanic Corrosion

“…Overall, the Raman analysis results indicated that the adsorbed water layers in the sliding H-DLC/SS interface suppress the transfer of H-DLC onto the SS counter-surface and induces oxidation of the SS wear debris. The identification and relative abundance of polymorphic iron oxide species were difficult and beyond the scope of this paper. − …”

Recent advances in linear and nonlinear Raman spectroscopy. Part VI

“…carried out the same kind of comparison between natural and synthesized finnemanite . Bauer and co‐workers reported on the Raman spectroscopy of laser‐induced oxidation of titanomagnetites, which are important carriers of magnetic remanence in nature and can track redox conditions in magma . Bourdoiseau and co‐workers studied the oxidation of mackinawite into greigite by using Raman spectroscopy .…”