Infrared- and Raman-Active Phonons of Magnetite, Maghemite, and Hematite:  A Computer Simulation and Spectroscopic Study

Chamritski, Irina; Burns, Gary R.

doi:10.1021/jp048748h

Cited by 366 publications

(286 citation statements)

References 31 publications

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Section: Methodsmentioning

confidence: 99%

“…Bands were assigned according to Raman databases: RASMIN (Raman Spectra Database of Minerals and Inorganic Materials, http://riodb.ibase.aist.go.jp/rasmin/E_index.htm) and RUFF (http://rruff.info/). Hematite and iron oxide bands were assigned according to [36,37] .In addition, the system was equipped with a head for atomic force microscopic imaging, which allowed measurement of the same sample position consecutively with both techniques. The AFM was mounted beneath a 10× objective (Nikon, air) and was operated in tapping mode using back-side gold-coated cantilevers (Nanosenors, PPP-NCT-Au, <10 nm tip radius).…”

mentioning

confidence: 99%

“…The peak at 138.9 cm -1 may have its origin from anatase (TiO 2 , fundamental mode at ~144 cm -1 ), a quartz-accompanying mineral, or aragonite (~154 cm -1 ). All reference peak values were taken from the Raman database RRUFF [33] and [36,37] . The broad carbonaceous material Bands D1 (at about 1340 cm -1 ), G (at about 1610 cm -1 ), S1 (at about 2670 cm -1 ) and S2 (at about 2940 cm -1 ) were found within the preserved organic parts of the cell.…”

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confidence: 99%

See 2 more Smart Citations

Laser‐Raman and atomic force microscopy assessment of the chlorococcalean affinity of problematic microfossils

Kremer

Bauer

Stark

et al. 2011

J Raman Spectroscopy

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Organic-walled microfossils of uncertain origin, classified to an informal group named acritarchs, are most commonly interpreted as the resting cysts of marine eukaryotic phytoplankton. Some acritarchs have recently been interpreted as vegetative cells of chlorococcalean green algae, based on internal bodies that have been interpreted as their asexual reproductive structures (spores). To verify this interpretation, we applied confocal Raman spectroscopy and atomic force microscopy (AFM) to study the ultrastructure and nanostructure of exceptionally preserved acritarchs with internal bodies from the early Silurian cherts (c. 430 Ma-old) of Frankenwald (Germany). Three-dimensional Raman mapping showed the spatial distribution of carbonaceous material and other minerals in the walls of the analysed internal bodies and confirmed that these structures are comparable with spores of chlorococcalean microalgae. Our findings document therefore the oldest thus far known vegetative cells of sporulating green algae. The combination of confocal Raman and AFM techniques yielded detailed information about the nanostructure and fossilisation mode of the mineralised organic walls of both the central vesicles and the enclosed spore-like bodies.Keywords: acritarch microfossils, mineralization, Silurian, Raman, AFM 2 IntroductionThe informal taxonomic category of organic-walled microfossils named acritarchs [1] has an unclear systematic affiliation. They are traditionally interpreted as the cysts of unicellular organisms. [1,2] During the Proterozoic and Paleozoic, acritarchs formed the basis of the marine food chain and played an important role in the evolution of the global ecosystem. Acritarchs were therefore the main primary producers in the ocean for a long time and, as oxygenic microorganisms, they must have not only controlled the evolution of the marine ecosystem but also influenced planetary biochemical cycles. Acritarch-like fossils are among the oldest morphological traces of life [3] , and the elucidation of their biological relationships sheds new light on the evolution of the early biosphere. It has recently been suggested that at least some acritarchs are the sporulating vegetative stages of unicellular green microalgae because they show internal bodies that can be interpreted as spores. [4] The classification of acritarchs as green algae therefore has an important bearing on the overall understanding of basic processes in the evolution of Earth's biosphere. A precise morphological and chemical characterisation of acritarch internal bodies and of their threedimensional arrangement is difficult because they are typically studied either in thin sections or after extraction from fossil-bearing rock. A detailed chemical or morphological study of microfossils usually requires physical or chemical preparation to extract the microfossils from the rock matrix, which can cause their partial or even total destruction. However, even the maceration process does not allow for extraction and study of these microfossils and their f...

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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Laser‐Raman and atomic force microscopy assessment of the chlorococcalean affinity of problematic microfossils

Kremer

Bauer

Stark

et al. 2011

J Raman Spectroscopy

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“…3. The non-doped catalyst Mn0 shows four distinct bands at approximately 195 cm −1 (T 2g ), 348 cm −1 (E 1g ), 497 cm −1 (T 2g ) and 693 cm −1 (A 1g ), respectively, close to the active phonon modes of maghemite in the study by Graves et al [48] and Chamritski et al [49]. With the increase of Mn substitution, the peaks at low wavenumber gradually decrease in intensity, and some of them even disappear for Mn1.0.…”

Section: Structure and Surface Characterization 331 Ramanmentioning

confidence: 59%

Effect of Mn substitution on the promoted formaldehyde oxidation over spinel ferrite: Catalyst characterization, performance and reaction mechanism

Liu

Wei

et al. 2016

Applied Catalysis B: Environmental

156

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“…The full width at half maximum for the rocking curve of the (111) To confirm the phase purity of Fe 3 O 4 in the film, Raman spectroscopy measurements have been performed since the Raman technique is very sensitive to the different phases of iron oxides on account of the vibrational frequencies of different compositions. 17 Figure. 1(b) shows a Raman spectrum of a Fe 3 O 4 thin film on a SiO 2 substrate.…”

Section: Film Characterizationmentioning

confidence: 99%

Unconventional magnetization of Fe3O4 thin film grown on amorphous SiO2 substrate

Yin

Liu

et al. 2016

AIP Advances

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High quality single crystal Fe3O4 thin films with (111) orientation had been prepared on amorphous SiO2 substrate by pulsed laser deposition. The magnetization properties of the films are found to be unconventional. The Verwey transition temperature derived from the magnetization jump is around 140K, which is higher than the bulk value and it can be slightly suppressed by out-plane magnetic field; the out-of-plane magnetization, which is unexpectedly higher than the in-plane value, is also significantly increased as compared with the bulk value. Our findings highlight the unusual magnetization of Fe3O4 thin film grown on the amorphous SiO2 substrate.

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Infrared- and Raman-Active Phonons of Magnetite, Maghemite, and Hematite: A Computer Simulation and Spectroscopic Study

Cited by 366 publications

References 31 publications

Laser‐Raman and atomic force microscopy assessment of the chlorococcalean affinity of problematic microfossils

Laser‐Raman and atomic force microscopy assessment of the chlorococcalean affinity of problematic microfossils

Effect of Mn substitution on the promoted formaldehyde oxidation over spinel ferrite: Catalyst characterization, performance and reaction mechanism

Unconventional magnetization of Fe3O4 thin film grown on amorphous SiO2 substrate

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