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Showing papers on "Infrared spectroscopy published in 2012"


Book ChapterDOI
22 Apr 2012
TL;DR: In this article, the electromagnetic spectrum in Figure 1 illustrates the many different types of electromagnetic radiation, including gamma rays (γ-rays), X-rays, ultraviolet (UV) radiation, visible light, infrared (IR), microwaves, and radio waves.
Abstract: Spectroscopy is the study of matter interacting with electromagnetic radiation (e.g., light). The electromagnetic spectrum in Figure 1 illustrates the many different types of electromagnetic radiation, including gamma rays (γ-rays), X-rays, ultraviolet (UV) radiation, visible light, infrared (IR) radiation, microwaves, and radio waves. The frequency (ν) and wavelength (λ) ranges associated with each form of radiant energy are also indicated in Figure 1.

849 citations


Journal ArticleDOI
TL;DR: Fourier transform infrared nanospectroscopy (nano-FTIR) based on a scattering-type scanning near-field optical microscope equipped with a coherent-continuum infrared light source can straightforwardly determine the infrared absorption spectrum of organic samples with a spatial resolution of 20 nm.
Abstract: We demonstrate Fourier transform infrared nanospectroscopy (nano-FTIR) based on a scattering-type scanning near-field optical microscope (s-SNOM) equipped with a coherent-continuum infrared light source. We show that the method can straightforwardly determine the infrared absorption spectrum of organic samples with a spatial resolution of 20 nm, corresponding to a probed volume as small as 10 zeptoliter (10–20 L). Corroborated by theory, the nano-FTIR absorption spectra correlate well with conventional FTIR absorption spectra, as experimentally demonstrated with poly(methyl methacrylate) (PMMA) samples. Nano-FTIR can thus make use of standard infrared databases of molecular vibrations to identify organic materials in ultrasmall quantities and at ultrahigh spatial resolution. As an application example we demonstrate the identification of a nanoscale PDMS contamination on a PMMA sample.

453 citations


Book ChapterDOI
23 May 2012
TL;DR: In this paper, the applicability of dispersion IR spectroscopy for natural fibres studies is discussed and a review by Annette, Sudhakar, Ursula and Andrea also demonstrates the application of this technique for natural fiber analysis.
Abstract: Infrared spectroscopy is nowadays one of the most important analytical techniques available to scientists. One of the greatest advantages of the infrared spectroscopy is that virtually any sample in any state may be analyzed. For example, liquids, solutions, pastes, powders, films, fibres, gases and surfaces can all be examined with a judicious choice of sampling technique. The review by Annette, Sudhakar, Ursula and Andrea [1-2] also demonstrates the applicability of dispersion infrared spectroscopy for natural fibres studies.

452 citations


Journal ArticleDOI
24 Aug 2012-ACS Nano
TL;DR: A dual-band perfect absorber based on a gold nanocross structure with two bands of maximum absorption of 94% is introduced and can be readily tuned throughout the mid-infrared with their associated resonances giving rise to large near-field enhancements.
Abstract: Metamaterial-based perfect absorbers utilize intrinsic loss, with the aid of appropriate structural design, to achieve near unity absorption at a certain wavelength. For most of the reported absorbers, the absorption occurs only at a single wavelength where plasmon resonances are excited in the nanostructures. Here we introduce a dual-band perfect absorber based on a gold nanocross structure. Two bands of maximum absorption of 94% are experimentally accomplished by breaking the symmetry of the cross structure. Furthermore, we demonstrate the two bands can be readily tuned throughout the mid-infrared with their associated resonances giving rise to large near-field enhancements. These features are ideal for multiband surface-enhanced infrared spectroscopy applications. We experimentally demonstrate this application by simultaneously detecting two molecular vibrational modes of a 4 nm thick polymer film utilizing our proposed absorber. Furthermore, in response to variations in the interaction strength betwee...

449 citations


Journal ArticleDOI
TL;DR: The ability to obtain spatially resolved IR spectra as well as high-resolution chemical images collected at specific IR wavenumbers was demonstrated and it was shown that by taking advantage of the ability to arbitrarily control the polarization direction of the IR excitation laser, it was possible to obtain important information regarding molecular orientation in electrospun nanofibers.
Abstract: Polymer and life science applications of a technique that combines atomic force microscopy (AFM) and infrared (IR) spectroscopy to obtain nanoscale IR spectra and images are reviewed. The AFM-IR spectra generated from this technique contain the same information with respect to molecular structure as conventional IR spectroscopy measurements, allowing significant leverage of existing expertise in IR spectroscopy. The AFM-IR technique can be used to acquire IR absorption spectra and absorption images with spatial resolution on the 50 to 100 nm scale, versus the scale of many micrometers or more for conventional IR spectroscopy. In the life sciences, experiments have demonstrated the capacity to perform chemical spectroscopy at the sub-cellular level. Specifically, the AFM-IR technique provides a label-free method for mapping IR-absorbing species in biological materials. On the polymer side, AFM-IR was used to map the IR absorption properties of polymer blends, multilayer films, thin films for active devices such as organic photovoltaics, microdomains in a semicrystalline polyhydroxyalkanoate copolymer, as well as model pharmaceutical blend systems. The ability to obtain spatially resolved IR spectra as well as high-resolution chemical images collected at specific IR wavenumbers was demonstrated. Complementary measurements mapping variations in sample stiffness were also obtained by tracking changes in the cantilever contact resonance frequency. Finally, it was shown that by taking advantage of the ability to arbitrarily control the polarization direction of the IR excitation laser, it is possible to obtain important information regarding molecular orientation in electrospun nanofibers.

431 citations


Journal ArticleDOI
TL;DR: In this article, a combined experimental and theoretical study on the vibrational properties of tenorite CuO and paramelaconite Cu4O3 was performed using Raman scattering and infrared absorption spectroscopy.
Abstract: A combined experimental and theoretical study is reported on the vibrational properties of tenorite CuO and paramelaconite Cu4O3. The optically active modes have been measured by Raman scattering and infrared absorption spectroscopy. First-principles calculations have been carried out with the LDA+U approach to account for strong electron correlation in the copper oxides. The vibrational properties have been computed ab initio using the so-called direct method. Excellent agreement is found between the measured Raman and infrared peak positions and the calculated phonon frequencies at the Brillouin zone center, which allows the assignment of all prominent peaks of the Cu4O3 spectra. Through a detailed analysis of the displacement eigenvectors, it is shown that a close relationship exists between the Raman modes of CuO and Cu4O3.

409 citations


Journal ArticleDOI
TL;DR: In this paper, a new structure for the inclusion complex has been proposed and the results showed that Raman spectroscopy would provide clearer and better evidence of inclusion complex formation than IR spectrograms.

358 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of thermal annealing on uncoated and coated magnetite nano-particles has been investigated using transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, infrared (IR) and Raman spectrographic analysis (TGA).

283 citations


Journal ArticleDOI
TL;DR: Methods to measure the phase, or phases, and disorder at a Ni(OH)(2) sample surface and to correlate desired chemical properties to their structural origins are established and unifies the large body of literature on the topic.
Abstract: The present work utilizes Raman and infrared (IR) spectroscopy, supported by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to re-examine the fine structural details of Ni(OH)(2), which is a key material in many energy-related applications. This work also unifies the large body of literature on the topic. Samples were prepared by the galvanostatic basification of nickel salts and by aging the deposits in hot KOH solutions. A simplified model is presented consisting of two fundamental phases (α and β) of Ni(OH)(2) and a range of possible structural disorder arising from factors such as impurities, hydration, and crystal defects. For the first time, all of the lattice modes of β-Ni(OH)(2) have been identified and assigned using factor group analysis. Ni(OH)(2) films can be rapidly identified in pure and mixed samples using Raman or IR spectroscopy by measuring their strong O-H stretching modes, which act as fingerprints. Thus, this work establishes methods to measure the phase, or phases, and disorder at a Ni(OH)(2) sample surface and to correlate desired chemical properties to their structural origins.

266 citations


Journal ArticleDOI
TL;DR: The results indicate that the β-sheet structures of raw legume proteins and the intermolecularβ-sheet aggregates, arising upon heating, are primary factors in adversely affecting the digestibility.
Abstract: The secondary structure of proteins in legumes, cereals, milk products and chicken meat was studied by diffuse reflectance infrared spectroscopy in the region of the amide I band. Major secondary structure components ( β-sheets, random coil, α-helix, turns), together with the low- and high-frequency side contributions, were resolved and related to the in vitro digestibility behaviour of the different foods. A strong inverse correlation between the relative spectral weights of the β-sheet structures and in vitro protein digestibility values was measured. Structural modifications in legume proteins induced by autoclaving were monitored by the changes in the amide I spectra. The results indicate that the β-sheet structures of raw legume proteins and the intermolecular β-sheet aggregates, arising upon heating, are primary factors in adversely affecting the digestibility.

255 citations


Journal ArticleDOI
TL;DR: These results not only provide fundamental insight into the electromagnetic response of Dirac fermions in graphene but also demonstrate the key functionalities of large-area graphene devices that are desired for components in terahertz and infrared optoelectronics.
Abstract: We have fabricated a centimeter-size single-layer graphene device with a gate electrode, which can modulate the transmission of terahertz and infrared waves. Using time-domain terahertz spectroscopy and Fourier-transform infrared spectroscopy in a wide frequency range (10–10 000 cm–1), we measured the dynamic conductivity change induced by electrical gating and thermal annealing. Both methods were able to effectively tune the Fermi energy, EF, which in turn modified the Drude-like intraband absorption in the terahertz as well as the “2EF onset” for interband absorption in the mid-infrared. These results not only provide fundamental insight into the electromagnetic response of Dirac fermions in graphene but also demonstrate the key functionalities of large-area graphene devices that are desired for components in terahertz and infrared optoelectronics.

Journal ArticleDOI
TL;DR: In this article, Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy was used to describe the ordering degree of anionic, cationic, and zwitterionic surfactants with the increase of their packing density on Ge substrate.
Abstract: This paper describes the ordering degree of anionic, cationic, and zwitterionic surfactants with the increase of their packing density on Ge substrate by using Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy. This work shows new insights on the conformational order of sodium dodecyl sulfate (SDS), N-hexadecyl-N-N-dimethyl-3-ammonio-1-propane-sulfonate (HPS), hexadecyl-trimethylammonium bromide (CTAB), and dodecyl trimethylammonium bromide (DTAB). DFT and semiempirical calculations are also performed in order to evaluate the effect of headgroup hydration and counterion. The CH2 asymmetric and symmetric stretching bands for the SDS molecule show a shift of 1.7 and 0.9 cm−1 to higher frequencies as the packing density increases, while it is observed a shift of 2.6 and 2.7 cm−1 for the HPS molecule, respectively. The DTAB molecule shows a shift of 4.5 cm−1 to lower frequencies for both CH2 asymmetric and symmetric stretching bands as the packing density increases, indicating the decrease of gauche conformations and the increase of all-trans conformations over the aliphatic chain.

Journal ArticleDOI
TL;DR: Compared with bare Fe particles, the high removal capacities of FGC are due to the increased adsorption sites in the hybrids, which are achieved by inhibiting the particle aggregation and reducing the size of Fe nanoparticles.

Journal ArticleDOI
TL;DR: In this paper, mesoporous hematite (α-Fe2O3) complex photocatalysts were successfully prepared using a facile solvent-thermal process in an aqueous solution.
Abstract: Carbon quantum dots (CQDs) and mesoporous hematite (α-Fe2O3) complex photocatalysts were successfully prepared using a facile solvent-thermal process in an aqueous solution. Mesostructured α-Fe2O3 clusters with a high surface area and a porous framework were an important consideration in the design of the photocatalysts because such structures enhance the absorption of photons and promote the decomposition of organic pollutants. More significantly, the CQDs in this catalyst play a pivotal role in improving the photocatalytic activity under visible light irradiation. The nanocomposites were characterized using X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, energy-dispersive spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, dynamic light scattering methods, ultraviolet-visible spectroscopy, and other techniques. The results confirmed the formation of CQD/mesoporous α-Fe2O3 hybrid clusters with a uniform size (about 700 nm), three-dimensional spherical morphologies, a large internal surface area (up to 187 m2 g−1), and a wormhole-like mesopore structure. Moreover, these novel composite catalysts displayed a continuous absorption band in the visible region. Photocatalytic studies of the CQD-embedded mesoporous α-Fe2O3 showed excellent photocatalytic efficiency (up to 97% capacity retention after three cycles) toward the degradation of organic compounds in aqueous media under visible light irradiation. The relationship between the physicochemical properties and the photocatalytic performance in our system is described and discussed on the basis of the results.

Journal ArticleDOI
TL;DR: An alternative deacylation mechanism for the photocatalytic oxidation of paracetamol is proposed and IR spectroscopy is demonstrated to be a useful technique to investigate oxidative mechanisms of pharmaceutical compounds.

Journal ArticleDOI
Huanhuan Li1, Wei Shi1, Kaina Zhao1, Han Li1, Yanmin Bing1, Peng Cheng1 
TL;DR: The results demonstrated that the Ni-doped MOF-5s not only exhibit larger Langmuir specific surface areas and larger pores than the undoped MOf-5, but also significantly enhance water resistance of the framework.
Abstract: Ni-doped MOF-5s were successfully synthesized for the first time via solvothermal crystallization process to enhance the hydrostability. Several characterization techniques, including X-ray diffraction (XRD), thermogravimetrical analysis (TGA), scanning electron microscopy (SEM), energy-dispersive spectroscopy instrument (EDS), inductively coupled plasma (ICP), infrared spectroscopy (IR), atomic sorption, diffuse-reflectance UV-vis spectroscopy, and gas sorption measurement, strongly support the effective incorporation of Ni(II) ions into the framework. The results demonstrated that the Ni-doped MOF-5s not only exhibit larger Langmuir specific surface areas and larger pores than the undoped MOF-5, but also significantly enhance water resistance of the framework. The H(2) uptake capacity of undoped MOF-5 drops rapidly when exposed to the ambient air, whereas the H(2) adsorptions of the Ni-doped MOF-5s remain stable for 4 days.

Journal ArticleDOI
TL;DR: The results provide a basis for intrinsic and extrinsic resonant manipulation of optical forces, control of nanoscale radiative heat transfer with optical antennas, and use of this new technique of thermal infrared near-field spectroscopy for broadband chemical nanospectroscopy.
Abstract: Despite the seminal contributions of Kirchhoff and Planck describing far-field thermal emission, fundamentally distinct spectral characteristics of the electromagnetic thermal near-field have been ...

Journal ArticleDOI
TL;DR: The results demonstrate that charge transfer from TiO(2) on a Pt/TiO( 2) catalyst controls the product distribution of furfuraldehyde hydrogenation by an acid-base mechanism.
Abstract: This work describes a molecular-level inves- tigation of strong metal−support interactions (SMSI) in Pt/ TiO2 catalysts using sum frequency generation (SFG) vibrational spectroscopy. This is the first time that SFG has been used to probe the highly selective oxide−metal interface during catalytic reaction, and the results demonstrate that charge transfer from TiO2 on a Pt/TiO2 catalyst controls the product distribution of furfuraldehyde hydrogenation by an acid−base mechanism. Pt nanoparticles supported on TiO2 and SiO2 are used as catalysts for furfuraldehyde hydrogenation. As synthesized, the Pt nanoparticles are encapsulated in a layer of poly(vinylpyrrolidone) (PVP). The presence of PVP prevents interaction of the Pt nanoparticles with their support, so identical turnover rates and reaction selectivity is observed regardless of the supporting oxide. However, removal of the PVP with UV light results in a 50-fold enhancement in the formation of furfuryl alcohol by Pt supported on TiO2, while no change is observed for the kinetics of Pt supported on SiO2. SFG vibrational spectroscopy reveals that a furfuryl-oxy intermediate forms on TiO2 as a result of a charge transfer interaction. This furfuryl-oxy intermediate is a highly active and selective precursor to furfuryl alcohol, and spectral analysis shows that the Pt/TiO2 interface is required primarily for H spillover. Density functional calculations predict that O-vacancies on the TiO2 surface activate the formation of the furfuryl-oxy intermediate via an electron transfer to furfuraldehyde, drawing a strong analogy between SMSI and acid−base catalysis.

Journal ArticleDOI
TL;DR: In this article, the potential of fiber optic reflection infrared spectroscopy for the non-invasive identification of artists' pigments is presented, considering their wide use during the history of art and their infrared optical properties.
Abstract: The potential of fibre optic reflection infrared spectroscopy for the non-invasive identification of artists’ pigments is presented. Sixteen different carbonate, sulphate and silicate-based pigments are taken into account considering their wide use during the history of art and their infrared optical properties. The infrared distortions mainly generated by the specular reflection are discussed on the basis of experimental measurements carried out on reference samples. The study on pure materials permitted the definition of marker bands, mainly combination and overtone modes, enhanced by the diffuse reflection component of the light, functional for the non-invasive pigment identification in real artworks. Several case studies are reported, including wall, easel, canvas paintings and manuscripts from ancient to modern art demonstrating the strengths of the technique on the identification of pigments even in the presence of complex mixtures of both organic (binders, varnishes) and inorganic (supports, fillers and other pigments) compounds.

Journal ArticleDOI
Xue Jiao1, Hongjie Song1, Huihui Zhao1, Wei Bai1, Lichun Zhang1, Yi Lv1 
TL;DR: In this article, a simple hydrothermal method was used to synthesize well-redispersed ceria nanoparticles (CeO2 NPs) for the detection of H2O2 and glucose.
Abstract: Well-redispersed ceria nanoparticles (CeO2 NPs) were synthesized by a simple hydrothermal method. The prepared CeO2 NPs exhibited excellent catalytic activity towards classical peroxidase substrate 3,3,5,5-tetramethylbiphenyl dihydrochloride (TMB·2HCl) in the presence of H2O2, based on which a colorimetric method that is highly sensitive and selective was developed for glucose detection. The composition, structure, morphology and peroxidase-like catalytic activity of CeO2 NPs are investigated in detail by using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FT-IR), thermal analysis (TG) and UV-vis absorption spectroscopy. According to this method, the detection of H2O2 and glucose are in linear range from 6.0 × 10−7 to 1.5 × 10−6 mol L−1 and 6.6 × 10−6 to 1.3 × 10−4 mol L−1, with the detection limit down to 5.0 × 10−7 mol L−1 H2O2 and 3.0 × 10−6 mol L−1 glucose, respectively. Further, this simple, cheap, highly sensitive and selective colorimetric method for glucose detection was successfully applied for the determination of glucose in human serum samples.


Journal ArticleDOI
TL;DR: In this article, the structural properties of polycrystalline Mg-Zn mixed ferrites with the general formula Mg1−xZnxFe2O4 (0≤x≤1) were investigated using X-ray diffraction and infrared absorption spectroscopy.
Abstract: Compositions of polycrystalline Mg–Zn mixed ferrites with the general formula Mg1−xZnxFe2O4 (0≤x≤1) were prepared by the standard double sintering ceramic method. The structural properties of these ferrites have been investigated using X-ray diffraction and infrared absorption spectroscopy. The lattice parameter, particle size, bonds length, force constants, density, porosity, shrinkage and cation distribution of these samples have been estimated and compared with those predicted theoretically. Most of these values were found to increase with increasing Zn content. The energy dispersive (EDS) analysis confirmed the proposed sample composition. The scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs showed aggregates of stacked crystallites of about 200–800 nm in diameter. Far infrared absorption spectra showed two significant absorption bands. The wave number of the first band, ν1, decreases with increasing Zn content, while the band, ν2 shifts linearly towards higher wave numbers with Zn contents, over the whole composition range. The room temperature electrical resistivity was found to decrease as Zn-content increases. Values of the vacancy model parameters showed that the packing factors Pa and Pb decrease, the fulfillment coefficient, α, remains almost constant and the vacancy parameter, β, strongly increases with increasing Zn content in the sample. The small values of Pa, Pb, α and the strong increase of the vacancy parameter, β, indicate the presence of cation or anion vacancies and the partial participation of the Zn2+ vacancies in the improvement of the electrical conductivity in the Mg–Zn ferrites.

Journal ArticleDOI
Wenchang Yan1, Dong Liu1, Daoyong Tan1, Peng Yuan1, Ming Chen1 
TL;DR: Progressive heat treatment was applied to palygorskite, and the changes of the position and intensity of its infrared vibrations, particularly those in the low wavenumber region, were monitored by use of Fourier transform infrared spectroscopy.

Journal ArticleDOI
TL;DR: Covalent attachment of a catalytically active cobalt complex onto boron-doped, p-type conductive diamond is reported, exhibiting good stability and electrocatalytic activity for electrochemical reduction of CO(2) to CO in acetonitrile solution.
Abstract: We report here covalent attachment of a catalytically active cobalt complex onto boron-doped, p-type conductive diamond. Peripheral acetylene groups were appended on a cobalt porphyrin complex, and azide–alkyne cycloaddition was used for covalent linking to a diamond surface decorated with alkyl azides. The functionalized surface was characterized by X-ray photoelectron spectroscopy and Fourier transform IR spectroscopy, and the catalytic activity was characterized using cyclic voltammetry and FTIR. The catalyst-modified diamond surfaces were used as “smart” electrodes exhibiting good stability and electrocatalytic activity for electrochemical reduction of CO2 to CO in acetonitrile solution.

Journal ArticleDOI
21 Sep 2012-Science
TL;DR: The number of water molecules needed to form the smallest ice crystals has proven challenging to pinpoint experimentally as discussed by the authors, which is why it has been difficult to pinpoint the number of molecules needed for the formation of the smallest water molecules.
Abstract: The number of water molecules needed to form the smallest ice crystals has proven challenging to pinpoint experimentally. This information would help to better understand the hydrogen-bonding interactions that account for the macroscopic properties of water. Here, we report infrared (IR) spectra of precisely size-selected (H 2 O) n clusters, with n ranging from 85 to 475; sodium doping and associated IR excitation–modulated photoionization spectroscopy allowed the study of this previously intractable size domain. Spectral features indicating the onset of crystallization are first observed for n = 275 ± 25; for n = 475 ± 25, the well-known band of crystalline ice around 3200 cm −1 dominates the OH-stretching region. The applied method has the potential to push size-resolved IR spectroscopy of neutral clusters more broadly to the 100- to 1000-molecule range, in which many solvents start to manifest condensed phase properties.

Journal ArticleDOI
TL;DR: In this article, the photocatalytic activity of a multi-component graphene-CdS-Pt composites for hydrogen generation was investigated, and the results showed that the composite containing 0.5 at% of Pt exhibits the highest hydrogen evolution rate of 123 mL h−1 g−1 with strong photostability.
Abstract: Graphene oxide–CdS–Pt (GO–CdS–Pt) nanocomposites with different amounts of Pt nanoparticles were successfully synthesized via the formic acid reduction process followed by a two-phase mixing method. The morphology, crystal phase and optical properties of obtained composites were well characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-vis spectroscopy, Fourier transform IR spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), respectively. The photocatalytic activity of GO–CdS–Pt composites for hydrogen generation was investigated. The results show that the GO–CdS–Pt composite containing 0.5 at% of Pt exhibits the highest hydrogen evolution rate of 123 mL h−1 g−1 with strong photostability, which is about 2.5 times higher than that of GO–CdS and 10.3 times higher than that of CdS. The increased photocatalytic hydrogen generation efficiency is attributed to the effective charge separation and decreased anti-recombination with the addition of GO and Pt, as well as the low overpotential of Pt for water splitting. Our findings pave a way to design multi-component graphene-based composites for highly efficient H2 generation and other applications.

Journal ArticleDOI
24 Jan 2012-ACS Nano
TL;DR: This work uses low-cost hole-mask colloidal nanolithography to manufacture large-area resonant split-ring metamaterials and measure their infrared optical properties, which has the potential to make resonant plasmon-enhanced infrared spectroscopy a standard lab tool in biology, pharmacology, and medicine.
Abstract: We use low-cost hole-mask colloidal nanolithography to manufacture large-area resonant split-ring metamaterials and measure their infrared optical properties. This novel substrate is employed for antenna-assisted surface-enhanced infrared absorption measurements using octadecanethiol (ODT) and deuterated ODT, which demonstrates easy adjustability of our material to vibrational modes. Our method has the potential to make resonant plasmon-enhanced infrared spectroscopy a standard lab tool in biology, pharmacology, and medicine.

Journal ArticleDOI
TL;DR: The persistence of the strong infrared absorption of the vibron characteristic of phase III indicates the stability of the paired state of hydrogen.
Abstract: Diamond-anvil-cell techniques have been developed to confine and measure hydrogen samples under static conditions to pressures above 300 GPa from 12 to 300 K using synchrotron infrared and optical absorption techniques. A decreasing absorption threshold in the visible spectrum is observed, but the material remains transparent at photon energies down to 0.1 eV at pressures to 360 GPa over a broad temperature range. The persistence of the strong infrared absorption of the vibron characteristic of phase III indicates the stability of the paired state of hydrogen. There is no evidence for the predicted metallic state over these conditions, in contrast to recent reports, but electronic properties consistent with semimetallic behavior are observed.

Journal ArticleDOI
TL;DR: The ultimate sensitivity performances obtained with a continuous wave-cavity ring down spectroscopy setup in the near infrared are investigated and it is shown that long term baseline fluctuations can be efficiently averaged over several days allowing the detection limit to be reached.
Abstract: The ultimate sensitivity performances obtained with a continuous wave-cavity ring down spectroscopy setup in the near infrared are investigated. At fixed frequency, the noise of the photodetector is found to be the main limitation and the best limit of detection (about 10−11 cm−1) is reached after a 10 s averaging. We show that long term baseline fluctuations can be efficiently averaged over several days allowing us to reach a detection limit as low as 5 × 10−13 cm−1. The achieved sensitivity is illustrated on narrow spectral intervals where the weakest lines detected so far by absorption spectroscopy are observed: (i) ultra-weak transitions of the a1Δg(0)−X 3Σg−(1) hot band of 16O2 near 1.58 μm and (ii) first detection of an electric quadrupole transition in the second overtone band of nitrogen (14N2) near 1.44 μm.

Journal ArticleDOI
TL;DR: In this paper, an elastic recoil detection analysis (ERDA) was used to measure the H contents of 18 synthetic Fo90 olivines that had been hydrated to varying degrees in high pressure hydrothermal experiments.