Showing papers in "Journal of Raman Spectroscopy in 2019"
218 citations
88 citations
TL;DR: All three compounds show much strongerBand intensities than unconjugated single aromatic rings, indicating that the bulk of the lignin structure has significantly reduced contribution to Raman band intensities, because low amounts of a compound do not necessarily mean weak features in the spectrum.
Abstract: Anatomical and chemical information can be linked by Raman imaging. Behind every pixel of the image is a Raman spectrum, which contains all the information as a molecular fingerprint. Yet to understand the spectra, the bands have to be assigned to components and their molecular structures. Although the lignin distribution is easily tracked in plant tissues, the assignment of the spectra is not good enough to allow in-depth analysis of the composition. Assignments of three lignin model compounds were derived from polarization measurements and quantum-chemical computations. Raman spectra of coniferyl alcohol crystals showed orientation dependence, which helped in band assignment. Abietin showed a Raman spectrum that was very similar to the spectrum of coniferyl alcohol, whereas its IR spectrum was very different due to bands of the sugar moiety. The Raman spectrum of coniferyl aldehyde is affected by the crystal order of molecules. All three compounds show much stronger band intensities than unconjugated single aromatic rings, indicating that the bulk of the lignin structure has significantly reduced contribution to Raman band intensities. Therefore, it is possible to highlight certain structures of lignin with Raman spectroscopy, because low amounts of a compound do not necessarily mean weak features in the spectrum.
49 citations
41 citations
TL;DR: In this article, the effect of modifying the substrate and/or growth temperature (600-1000°C) of graphene synthesis was investigated by Raman micro-spectroscopy mapping, showing that modifying the growth temperature had different effects when a Si(100) or a SiO 2 substrate is used.
Abstract: We report the results of a comparative investigation of graphene films prepared on Si(100) and fused silica (SiO 2) combining pulsed laser deposition and rapid thermal annealing using Ni catalyst. The effect of modifying the substrate and/or growth temperature (600-1000°C) of graphene synthesis was investigated by Raman micro-spectroscopy mapping. Graphene grown on Si(100) was multilayered, and various nickel silicide phases had formed underneath, revealing dependence on the growth temperature. Films prepared on SiO 2 mainly comprised bi-and tri-layered graphene, with no traces of nickel silicide. Analysis of Raman D, G, and 2D peak intensities and positions showed that modifying the growth temperature had different effects when a Si(100) or a SiO 2 substrate is used. These findings advance our understanding of how different combinations of substrate and thermal processing parameters affect graphene synthesis from solid carbon source using nickel as a catalyst. This knowledge will enable better control of the properties of graphene film (defects, number of layers, etc.), and will have a high potential impact on the design of graphene-based devices for scientific or industrial applications.
40 citations
TL;DR: In this paper, the Stokes and anti-Stokes Raman spectra were measured at one temperature only, and the difference between the two parts of the spectrum was used to distinguish between first and second order phonon bands.
Abstract: We show the interest in recording both Stokes and anti‐Stokes Raman spectra in two peculiar applications. In one case, the comparison between these two parts of the spectrum, measured at one temperature only, allows to distinguish between first‐ and second‐order phonon bands. In the second example, the difference between Stokes and anti‐Stokes spectra provides separation between vibrational and emission lines. We describe the different stages needed in the measurements and data treatment.
40 citations
TL;DR: In this article, a sample of kimberlite-related melts were entrapped as secondary melt inclusions hosted in olivine from sheared peridotite xenoliths from the Udachnaya-east pipe (Siberian craton).
Abstract: The study of kimberlite rocks is important as they provide critical information regarding the composition and dynamics of the continental mantle and are the principal source of diamonds. Despite many decades of research, the original compositions of kimberlite melts, which are thought to be derived from depths > 150 km, remain highly debatable due to processes that can significantly modify their composition during ascent and emplacement. Snapshots of the kimberlite‐related melts were entrapped as secondary melt inclusions hosted in olivine from sheared peridotite xenoliths from the Udachnaya‐East pipe (Siberian craton). These xenoliths originated from 180‐ to 220‐km depth and are among the deepest derived samples of mantle rocks exposed at the surface. The crystallised melt inclusions contain diverse daughter mineral assemblages (>30 mineral species), which are dominated by alkali‐rich carbonates, sulfates, and chlorides. The presence of aragonite as a daughter mineral suggests a high‐pressure origin for these inclusions. Raman‐mapping studies of unexposed inclusions show that they are dominated by carbonates (>65 vol.%), whereas silicates are subordinate (<13 vol.%). This indicates that the parental melt for the inclusions was carbonatitic. The key chemical features of this melt are very high contents of alkalis, carbon dioxide, chlorine, and sulfur and extremely low silica and water. Alkali‐carbonate melts entrapped in xenolith minerals likely represent snapshots of the primitive kimberlite melt. This composition is in contrast with the generally accepted notion that kimberlites originated as ultramafic silicate water‐rich melts. Experimental studies revealed that alkali‐carbonate melts are a very suitable diamond‐forming media. Therefore, our findings support the idea that some diamonds and kimberlite magmatism may be genetically related.
40 citations
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31 citations
TL;DR: It is demonstrated that utilization of a hand‐held Raman spectrometer in combination with chemometric analyses enables detection and identification of the secondary disease such as blight on HLB‐infected orange trees (HLB + BL).
Abstract: J Raman Spectrosc. 2019;1–6. Abstract Huanglongbing (HLB), or citrus greening, is a devastating disease of citrus that is debilitating the U.S. citrus industry. The infected trees exhibit yellowing leaves, premature defoliation, and ultimately death of the entire plant. In addition to the devastating impact of HLB alone, infected trees become an easy target for other diseases. This further decreases the fruit yield, shortens the tree life, and complicates management practices. Raman spectroscopy is a noninvasive and nondestructive analytical technique that provides insight on the chemical structure of a specimen. In this study, we demonstrate that utilization of a hand‐held Raman spectrometer in combination with chemometric analyses enables detection and identification of the secondary disease such as blight on HLB‐infected orange trees (HLB + BL). We also showed that using this spectroscopic approach, we could detect and identify canker and distinguish this disease from healthy trees, HLB, and HLB + BL with high accuracy.
31 citations
TL;DR: The European Regional Development Fund (ERDF) provided a grant for the storage and conservation of 20th century cultural heritage of artefacts based on cellulose derivatives, with a grant/award number of H2020-NMBP-35-2017 grant 76081 as discussed by the authors.
Abstract: Funding information European Regional Development Fund, Grant/Award Number: POCI‐01‐0145‐ FERDER ‐ 007265; FCT/MEC, Grant/ Award Number: UID/QUI/50006/2013; Fundação para a Ciência e a Tecnologia, Grant/Award Numbers: CORES‐PD/ 00253/2012, PB/BD/114412/2016, SFRH/ BD/72560/2010 and UID/QUI/50006/ 2013; NEMOSINE ‐ Innovative packaging solutions for storage and conservation of 20th century cultural heritage of artefacts based on cellulose derivatives, Grant/ Award Number: H2020-NMBP‐35‐2017 ‐ grant 76081
TL;DR: In this article, a ripple-like nanostructures (NSs) were fabricated on an iron substrate using femtosecond (fs) laser irradiation of the target in distilled water.
Abstract: J Raman Spectrosc. 2019;1–11. Abstract During the past several years, numerous efforts have been accomplished on designing efficient surface‐enhanced Raman scattering (SERS) substrates with high sensitivity, good reproducibility, and recyclable nature. However, it still remains a significant challenge to realize all these qualities in a single substrate. We have fabricated ripple‐like nanostructures (NSs) on Iron (Fe) substrate using femtosecond (fs) laser irradiation of Fe target in distilled water. These ripple‐like structures had periodicities in the range of ~90–190 nm, which was confirmed from the analysis of field emission scanning electron microscope (FESEM) data. We subsequently deposited a thin layer of gold on these ripple‐like Fe NSs using thermal evaporation. Later, these coated NSs were effectively utilized as SERS substrates for methylene blue (MB) detection and were found to be sensitive evident from the data obtained at a very low concentration of 500pM. Furthermore, we observed that the SERS signal variations on the substrate were <11.2% indicating the reproducible nature of these substrates. Additionally, we demonstrate that these substrates can be reused (we establish this for three times consecutively) by detecting malachite green (MG) and an explosive molecule (picric acid, PA) followed by the mixture compound (Rhodamine 6G+MB) through employment of simple cleaning procedures. The detected molecular concentrations in terms of masses were found to be 3.2 pg, 36.5 pg, and 23 ng for MB (for a concentration of 500pM), MG (for a concentration of 5nM), and PA (for a concentration of 5μM), respectively. Furthermore, these Fe NSs exhibited superior batch‐to‐batch reproducibility with a relative standard deviation (RSD) value of ~l4%. The proposed method of fabricating ripple structures as SERS platforms are highly feasible, reliable, and have great potential for on‐site detection of several analyte molecules with an easily transportable Raman spectrometer.
TL;DR: A four‐stage step‐by‐step transformation mechanism is first proposed to describe the exact kinetics of lysozyme amyloid fibrillation under heat and acidic conditions, which provides necessary information for physiologists to artificially control the amyloids formation of neurodegenerative disease patients.
Abstract: J Raman Spectrosc. 2019;50:629–640. Abstract Amyloid fibrillation of proteins is a hallmark of neurodegenerative disease, accompanied by the formation of the organized cross‐β cores. This conformational transformation is considered to be related to the toxicity underlying the pathogenic mechanism. However, the exact conformational transformation kinetics of amyloid fibrillation are not fully understood. Herein, Raman spectroscopy was used to detect the transformation in the molecular structure of hen egg white lysozyme during amyloid formation under heat and acidic conditions (pH 2.0 and 65°C). The overall kinetics of the hen egg white lysozyme conformational change were investigated by analyzing five characteristic spectral fingerprints. The two N―Cα―C stretching bands at 899 and 935 cm −1 and the amide I band (at 1,640–1,680 cm) correlated to the lysozyme skeleton structure, whereas the band of the Phe amino acid group in side chains at 1,003 cm and the two Trp residue bands at 760 and 1,340–1,360 cm were associated with the tertiary structure. Based on these results, a four‐stage step‐by‐step transformation mechanism is first proposed to describe the exact kinetics of lysozyme amyloid fibrillation under heat and acidic conditions. This provides necessary information for physiologists to artificially control the amyloid formation of neurodegenerative disease patients.
TL;DR: In this article, the effects of oxygen isotopic substitution were examined in terms of disorder and size-related effects on thin zirconia layers grown on Zirconium alloys simulating in-reactor materials.
Abstract: Recently, unusual Raman signals were observed in different works conducted on thin zirconia layers grown on zirconium alloys simulating in‐reactor materials after high fluence ion irradiation or for samples cut from fuel rods irradiated in nuclear plants. As such, these spectra clearly do not correspond to any known spectrum of a pure standard zirconia phase. Therefore, the analysis conducted in this paper aims to provide a better understanding of these peculiar Raman features. For that purpose, specific ion‐irradiated samples were analysed. In situ Raman spectroscopy was first used to follow the irradiation process. Then, samples were characterized using different excitation wavelengths. Finally, the effects of oxygen isotopic substitution were examined in details. Results are discussed in terms of disorder and size‐related effects.
TL;DR: In this article, Shi et al. proposed a divergence-imPLICation approach for MARS and EUROPA in the context of the Shandong Provincial Key Laboratory of Optical Astronomy & Solar-Terrestrial Environment.
Abstract: DEGREES -IMPLICATION FOR MARS AND EUROPA. Erbin Shi, Zongcheng Ling, Alian Wang, Institute of Space Sciences and Shandong Provincial Key Laboratory of Optical Astronomy & Solar-Terrestrial Environment, Shandong University, Weihai, 264209, China; Department of Earth & Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, MO, 63130 (irvingshi@epsc.wustl.edu).