Fabry-Perot interference pattern scattered by a sub-monolayer array of nanoparticles

Understanding scattering of visible and infrared photons from nanomaterials and nanostructured materials is increasingly important for imaging, thermal management, and detection, and has implications for other parts of the electromagnetic spectrum (e.g., x-ray scattering and radar). New, interesting reports of photon scattering as a diagnostic probe, from inelastic x-ray scattering and interference to “nano-FTIR” microscopy using infrared photons, have been published and are under active investigation in laboratories around the world. Here, we report, for the first time to our best knowledge, the experimental discovery of a Fabry-Perot interference pattern that is scattered by the sub-monolayer array of plasmonic Ag nanoparticles, and confirm it analytically and with rigorous numerical FDTD simulations.

Monitoring the chemical changes in fingermark residue over time using synchrotron infrared spectroscopy

Degradation of fingermark residue has a major impact on the successful forensic detection of latent fingermarks. The time course of degradation has been previously explored with bulk chemical analyses, but little is known about chemical alterations at the micron-scale. Here we report the use of synchrotron-sourced attenuated total reflection-Fourier transform infrared (ATR-FTIR) microscopy to provide spatio-temporal resolution of chemical changes within fingermark droplets, as a function of time since deposition. Eccrine and sebaceous material within natural fingermark droplets were imaged on the micron scales at hourly intervals for the first 6 – 12 hours after deposition, revealing that substantial dehydration occurred within the first 8 hours. Changes to lipid material was more varied, with samples exhibiting an increase or decrease in lipid concentration due to the degradation and redistribution of this material. Across 12 donors, it was noticeable that the initial chemical composition and morphology of the droplet varied greatly, which appeared to influence on the rate of change of the droplet over time. Further, this study attempted to quantify the total water content within fingermark samples. The wide-spread nature and strength of the absorption of Terahertz/Far-infrared (THz/Far-IR) radiation by water vapour molecules were exploited for this purpose, using THz/Far-IR spectroscopy. Upon heating, water confined in natural fingermarks was evaporated and expanded in a vacuum chamber equipped with multipass optics. The amount of water vapour was then quantified by high-spectral resolution analysis, and fingermarks were observed to lose approximately 14 – 20 µg of water. The combination of both ATR-FTIR and Far-IR highlight important implications for experimental design in fingermark research, and operational practices used by law enforcement agencies.

Metabolite Quantification by Fourier Transform Infrared Spectroscopy in Diatoms: Proof of Concept on Phaeodactylum tricornutum

Diatoms are feedstock for the production of sustainable biocommodities, including biofuel. The biochemical characterization of newly isolated or genetically modified strains is seminal to identify the strains that display interesting features for both research and industrial applications. Biochemical quantification of organic macromolecules cellular quotas are time-consuming methodologies which often require large amount of biological sample. Vibrational spectroscopy is an essential tool applied in several fields of research. A Fourier transform infrared (FTIR) microscopy-based imaging protocol was developed for the simultaneous cellular quota quantification of lipids, carbohydrates, and proteins of the diatom Phaeodactylum tricornutum. The low amount of sample required for the quantification allows the high throughput quantification on small volume cultures. A proof of concept was performed (1) on nitrogen-starved experimental cultures and (2) on three different P. tricornutum wild-type strains. The results are supported by the observation in situ of lipid droplets by confocal and brightfield microscopy. The results show that major differences exist in the regulation of lipid metabolism between ecotypes of P. tricornutum.

Vnir reflectance spectroscopyof Mercury like glasses

<p>Glassy materials have been recognized over Mars, Moon and many different meteorites (Farrand et al. 2016; Delano 1986; Varela & Kurat 2004). Planetary glasses result from impact events but they are also found as volcanic products (Farrand et al 2016). Morlock et al. (2017) and Morlok et al. (2021) investigated by means of different experimental techniques (bi-directional diffuse reflectance FTIR, in situ FTIR microscopy, Raman, EPMA and optical microscopy) a suite of synthetic samples with composition similar to those inferred for different Hermean terrains. Here we extended the study of the same materials to the VNIR region (bidirectional reflectance spectroscopy: 350 to 2500 nm). We analyzed 8 different samples with different chemical compositions, produced under different oxygen fugacity conditions We prepared eight granulometric classes between 0 and 250 μm, namely: 0-25; 25-63; 63-100; 100-125; 125-150; 150-180; 180-200 and 200-250 μm. The dominant feature in the VNIR region is due to the Fe absorption band at about 1 μm accompanied, in the more oxidized samples, by a smaller feature at 480 nm likely due to ferric oxide development. Iron free samples (FeO < 0.1 wt%) show characteristic spectral shapes with a distinctive feature at about 640 nm attributable to TiO2. Even for very low FeO content, it is possible to observe a weak yet clear band at about 900-1000 nm due to Fe absorption which explain the dominance of the spectral features due to Fe absorption at higher FeO content. Additional small bands at higher wavelengths (1300-1400 and 1900 nm) suggest a low content of water and/or –OH species in the samples. We investigated the spectral features as a function of composition, grain size and oxidation in order to gain as much information as possible on the nature of the spectra and compare them with remote sensing data or meteorites VNIR comparison. Our data on synthetic and realistic Hermean compositions will allow a better understanding of remotely acquired VisNIR spectra, which will be particularly helpful in view of the upcoming beginning of the BepiColombo ESA/JAXA mission.</p> <p> </p> <p>Acknowledgments: The authors acknowledge financial contribution from the Italian Space Agency (ASI) under ASI-INAF agreement 2017-47-H.0 (Simbio-SYS). CC, EB are also supported by agreement ASI-INAF n.2018-16-HH.0.</p>

Study of Organic Matter of Unconventional Reservoirs by IR Spectroscopy and IR Microscopy

The study of organic matter content and composition in source rocks using the methods of organic geochemistry is an important part of unconventional reservoir characterization. The aim of this work was the structural group analysis of organic matter directly in the source rock in combination with a quantitative assessment and surface distribution analysis of the rock sample by FTIR spectroscopy and FTIR microscopy. We have developed new experimental procedures for semi-quantitative assessment of the organic matter content, composition and distribution in the source rocks and applied these procedures for the study of the samples from the Bazhenov shale formation (West Siberia, Russia). The results have been verified using the data from the study of organic matter obtained by Rock-Eval pyrolysis and differential thermal analysis. The obtained results demonstrate the prospects of FTIR spectroscopy and FTIR microscopy application for non-destructive and express analysis of the chemical structure and distribution of organic matter in rocks.

Silver and Gold Nanoparticles from Limnophila rugosa Leaves: Biosynthesis, Characterization, and Catalytic Activity in Reduction of Nitrophenols

This study describes a simple green method for the synthesis of Limnophila rugosa leaf-extract-capped silver and gold nanoparticles without using any expensive toxic reductant or stabilizer. The noble metal nanoparticles were characterized by Fourier transform infrared (FTIR) microscopy, powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray analysis (EDX), high-resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), and dynamic light scattering (DLS) method. It has been found that the biosynthesized silver and gold nanoparticles are nearly spherical in shape with a mean particle size distribution of 87.5 nm and 122.8 nm, respectively. XRD and SAED patterns confirmed the crystalline nanostructure of the metal nanoparticles. FTIR spectra revealed the functional groups of biomolecules presented in the extract possibly responsible for reducing metallic ions and stabilizing formed nanoparticles. The biosynthesized metal nanoparticles have potential application in catalysis. Compared to previous reports, Limnophila rugosa leaf-extract-capped silver and gold nanoparticles exhibited a good catalytic activity in the reduction of several derivatives of nitrophenols including 1,4-dinitrobenzene, 2-nitrophenol, 3-nitrophenol, and 4-nitrophenol.

Effective Degradation of Cigarette Butts via Treatment with Old Landfill Leachates

In this paper, results of feasibility study on microplastics (MPs) assessment in leachates from the Latvian solid municipal landfill Getliņi are discussed. The application of leachates for the treatment of cigarette butts (CGB) was evaluated. Methods of fluorescent microscopy, Fourier transform infrared (FTIR) spectroscopy and FTIR-microscopy were used for the identification and characterization of MPs in the leachates and analysis of CGB. Presence of the secondary MPs (e.g., degraded polyolefin mixtures) was determined in the tested landfill leachates, while cellulose acetate (CA) was not determined in these products. The leachates were tested as potential media for the thermophilic (55°C) fermentation of CGB without air supply. Degradation of CGB was determined after one-week fermentation that was confirmed comparing the changes in FTIR spectra of CA prior and after the treatment. This study provoked a path for further experimental studies of controlled degradation of cigarette butts under natural conditions in landfill environments.

Tracking biochemical changes induced by iron loading in AML12 cells with Synchrotron live cell, time-lapse infrared microscopy

Hepatocytes are essential for maintaining homeostasis of iron and lipid metabolism in mammals. Dysregulation of either iron or lipids has been linked with serious health consequences, including non- alcoholic fatty liver disease (NAFLD). Considered the hepatic manifestation of metabolic syndrome, NAFLD is characterised by dysregulated lipid metabolism leading to a lipid storage phenotype. Mild to moderate increases in hepatic iron have been observed in approximately 30% of individuals with NAFLD; however, direct observation of the mechanism behind this increase has remained elusive. To address this issue, we sought to determine the metabolic consequences of iron loading on cellular metabolism using live cell, time-lapse Fourier transform infrared (FTIR) microscopy utilising a synchrotron radiation source to track biochemical changes. Use of Synchrotron FTIR is non-destructive and label-free, and allowed observation of spatially-resolved, sub-cellular biochemical changes over a period of 8 hours. Using this approach, we have demonstrated that iron loading in AML12 cells induced perturbation of lipid metabolism congruent with steatosis development. Iron loaded cells had approximately three times higher relative ester carbonyl concentration compared to controls, indicating accumulation of triglycerides. The methylene/methyl ratio qualitatively suggests the acyl chain length of fatty acids in iron loaded cells increased over the 8 hour period of monitoring compared to a reduction observed in the control cells. Our findings provide direct evidence that mild to moderate iron loading in hepatocytes drives de novo lipid synthesis, consistent with a role for iron in the initial hepatic lipid accumulation that leads to development of hepatic steatosis.