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Applied Spectroscopy

Justin M Reynard, Nathan S Van Gorder, Frank V Bright
We report on gaseous analyte-induced photoluminescence (PL) quenching of porous silicon, as-prepared (ap-pSi) and oxidized (ox-pSi). By using steady-state and emission wavelength-dependent time-resolved intensity luminescence measurements in concert with a global analysis scheme, we find that the analyte-induced quenching is best described by a three-component static quenching model. In the model, there are blue, green, and red emitters (associated with the nanocrystallite core and surface trap states) that each exhibit unique analyte-emitter association constants and these association constants are a consequence of differences in the pSi surface chemistries...
September 2017: Applied Spectroscopy
Andrew Johnston, Keith Rogers
The effect of moderate temperatures (25-75 ℃) on latent fingerprints over a five-hour period was examined using Fourier transform infrared (FT-IR) microspectroscopy. The aim of the study was to detect changes in IR spectra due to any changes in fingerprint chemistry; these results were then compared to pure compounds found in sebum that was subjected to 75 ℃ for 5 h. Latent fingerprints deposited on CaF2 microscope slides and placed on a Peltier pump heating stage showed that higher temperatures significantly reduced the quantity of sebaceous compounds after 5 h, whereas temperatures below 45 ℃ had little effect on the quantity of these compounds over the same time period...
September 2017: Applied Spectroscopy
(no author information available yet)
No abstract text is available yet for this article.
September 2017: Applied Spectroscopy
Saranjam Khan, Rahat Ullah, Asifullah Khan, Anabia Sohail, Noorul Wahab, Muhammad Bilal, Mushtaq Ahmed
This work presents the evaluation of Raman spectroscopy using random forest (RF) for the analysis of dengue fever in the infected human sera. A total of 100 dengue suspected blood samples, collected from Holy Family Hospital, Rawalpindi, Pakistan, have been used in this study. Out of these samples, 45 were dengue-positive based on immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (ELISA) tests. For highlighting the spectral differences between normal and infected samples, an effective machine learning system is developed that automatically learns the pattern of the shift in spectrum for the dengue compared to normal cases and thus is able to predict the unknown class based on the known example...
September 2017: Applied Spectroscopy
Martha Z Vardaki, Hannah Sheridan, Nicholas Stone, Pavel Matousek
This study demonstrates experimentally a method to enable prediction of depth of a chemical species buried in a turbid medium by using transmission Raman spectroscopy alone. The method allows the prediction of the depth of a single, chemically distinct layer within a turbid matrix by performing two measurements, with and without a beam enhancing element, or "photon diode." The samples employed consisted of two different polymers, of total thickness 3.6 mm, whose optical properties are loosely relevant to pharmaceutical applications...
August 2017: Applied Spectroscopy
Joseph P Smith, Frank C Smith, Joshua Ottaway, Alexandra E Krull-Davatzes, Bruce M Simonson, Billy P Glass, Karl S Booksh
The high-pressure, α-PbO2-structured polymorph of titanium dioxide (TiO2-II) was recently identified in micrometer-sized grains recovered from four Neoarchean spherule layers deposited between ∼2.65 and ∼2.54 billion years ago. Several lines of evidence support the interpretation that these layers represent distal impact ejecta layers. The presence of shock-induced TiO2-II provides physical evidence to further support an impact origin for these spherule layers. Detailed characterization of the distribution of TiO2-II in these grains may be useful for correlating the layers, estimating the paleodistances of the layers from their source craters, and providing insight into the formation of the TiO2-II...
August 2017: Applied Spectroscopy
Georg Ramer, Florian Reisenbauer, Benedikt Steindl, Wolfgang Tomischko, Bernhard Lendl
Photothermal-induced resonance (PTIR) is a method for optical spectroscopy that allows for infrared (IR) chemical imaging at spatial resolution below the limit of diffraction. By using the mechanical resonance of the cantilever for amplification the technique has been shown to allow sensitivity down to single monolayers. In this work, we discuss the challenges that must be overcome for performing stable resonant PTIR measurements and how imprecise experimental procedures can lead to irreproducible or even erroneous results...
August 2017: Applied Spectroscopy
Laetitia Garoux, Sébastien Gourhand, Marc Hébrant, Michel Schneider, Sébastien Diliberto, Eric Meux
Petroleum industries continuously consume catalysts on very large scales. The recycling of spent catalysts is thus of major economic and environmental importance and its first step consists of the characterization of the valuable metal content. Wavelength dispersive X-ray fluorescence (WDXRF) analysis is compared with inductively coupled plasma atomic emission spectrometry (ICP-AES) for the analysis of five samples of spent hydrodesulphurization (HDS) and hydrodemetallization (HDM) catalysts. The elements are considered for their economic interest (Co, Ni, Mo, and V) or for the problems that can arise when they are present in the sample in significant quantities (Al, As, P, Fe)...
August 2017: Applied Spectroscopy
Aaron J Specht, Farshad Mostafaei, Yanfen Lin, Jian Xu, Linda H Nie
Measurement of bone strontium (Sr) is vital to determining the effectiveness of Sr supplementation, which is commonly used for the treatment of osteoporosis. Previous technology uses radioisotope sources and bulky equipment to measure bone Sr. This study demonstrates the effectiveness of portable X-ray fluorescence (XRF) for bone Sr measurement and validates it using data from a population of 238 children. We identified correlations between bone Sr and age in our participants.
August 2017: Applied Spectroscopy
Letizia Bonizzoni, Marco Gargano, Nicola Ludwig, Marco Martini, Anna Galli
Non-invasive, portable analytical techniques are becoming increasingly widespread for the study and conservation in the field of cultural heritage, proving that a good data handling, supported by a deep knowledge of the techniques themselves, and the right synergy can give surprisingly substantial results when using portable but reliable instrumentation. In this work, pigment characterization was carried out on 21 Leonardesque paintings applying in situ X-ray fluorescence (XRF) and fiber optic reflection spectroscopy (FORS) analyses...
August 2017: Applied Spectroscopy
Sameer Talwar, Rahul Roopwani, Carl A Anderson, Ira S Buckner, James K Drennen
Near-infrared chemical imaging (NIR-CI) combines spectroscopy with digital imaging, enabling spatially resolved analysis and characterization of pharmaceutical samples. Hardness and relative density are critical quality attributes (CQA) that affect tablet performance. Intra-sample density or hardness variability can reveal deficiencies in formulation design or the tableting process. This study was designed to develop NIR-CI methods to predict spatially resolved tablet density and hardness. The method was implemented using a two-step procedure...
August 2017: Applied Spectroscopy
(no author information available yet)
No abstract text is available yet for this article.
August 2017: Applied Spectroscopy
Jun Zhao, Kristen Frano, Jack Zhou
A reverse intensity correction method was developed for spectral library searches to correct for instrument response without the side effect of magnifying the noise in the low responsivity region of test spectra. Instead of applying relative intensity correction to the sample test spectra to match the standardized library spectra, a reverse intensity correction is applied to the standardized library spectra to match the uncorrected sample spectrum. This simple procedural change improves library search performance, especially for dispersive charge-coupled device Raman analyzers using near-infrared excitations, where the instrument response often varies greatly across the spectral range, and signal-to-noise ratio in the low responsivity regions is typically poor...
August 2017: Applied Spectroscopy
Young Jong Lee
Least squares regression is proposed as a moving-windows method for analysis of a series of spectra acquired as a function of external perturbation. The least squares moving-window (LSMW) method can be considered an extended form of the Savitzky-Golay differentiation for nonuniform perturbation spacing. LSMW is characterized in terms of moving-window size, perturbation spacing type, and intensity noise. Simulation results from LSMW are compared with results from other numerical differentiation methods, such as single-interval differentiation, autocorrelation moving-window, and perturbation correlation moving-window methods...
August 2017: Applied Spectroscopy
Winfried Nischkauer, Andrei Izmer, Marie-Alexandra Neouze, Frank Vanhaecke, Andreas Limbeck
A combination of analyte pre-concentration using dispersed particle extraction (DPE) and dried-droplet laser ablation inductively coupled mass spectrometry (LA-ICP-MS) was developed with the aim to quantify Pt and Pd in urban particulate matter with an aerodynamic diameter ≤2.5 µm (PM2.5). The PM2.5 aerosol was collected on cellulose ester filters during a sampling period of three days, with sampling intervals of 4 h only. Each of the filters was chemically digested, and the resulting solution was pre-concentrated using DPE...
July 2017: Applied Spectroscopy
Leonardo Bennun
A new smoothing method for improvement on the quantification of spectral signals, which requires the previous knowledge of the functions that should be quantified, is presented. These functions are used as weighted coefficients in the proposed smoothing algorithm. This method is extremely effective in reducing the scatter of signals obtained by the multichannel analyzer and it could be applied in atomic and nuclear spectroscopies, preferably to these techniques where net counts are a linear function of the acquisition time, like total reflection X-ray fluorescence, micro X-ray fluorescence, etc...
July 2017: Applied Spectroscopy
Chafia Benmouhoub, Bernard Gauthier-Manuel, Ameur Zegadi, Laurent Robert
Due to its impressive optical properties, lithium niobate (LiNbO3) is considered to be one of the most important ferroelectric materials. Its uses in sensing platforms require functionalization at the surface to enable the capture and quantifying of molecules. The current paper aims to demonstrate the covalent bonding of aminosilane layers to the LiNbO3 surface. Fourier transform infrared (FT-IR) analysis reveals the presence of an NbO-Si bond observable as a shoulder at the same wavenumber (975 cm(-1)) on the surfaces of LiNBO3 as well as on those of Nb2O5, using 3-(aminopropyl)trimethoxysilane (APTMS) or 3-(aminopropyl)methyldimethoxysilane (APDMS) precursors...
July 2017: Applied Spectroscopy
Valery Sizikov, Denis Sidorov
An inverse problem in spectroscopy is considered. The objective is to restore the discrete spectrum from observed spectrum data, taking into account the spectrometer's line spread function. The problem is reduced to solution of a system of linear-nonlinear equations (SLNE) with respect to intensities and frequencies of the discrete spectral lines. The SLNE is linear with respect to lines' intensities and nonlinear with respect to the lines' frequencies. The integral approximation algorithm is proposed for the solution of this SLNE...
July 2017: Applied Spectroscopy
Camiel H van Hoorn, Carlos Wessels, Freek Ariese, Arjan J G Mank
A fast high-resolution screening method for reactive surfaces is presented. Atomic force microscopy (AFM) and surface-enhanced Raman spectroscopy (SERS) are combined in one method in order to be able to obtain both morphological and chemical information about processes at a surface. In order to accurately align the AFM and SERS images, an alignment pattern on the substrate material is exploited. Subsequent SERS scans with sub-micron resolution are recorded in 30 min per scan for an area of 100 × 100 µm(2) and are accompanied by morphological information, supplied by a fast AFM, of the same area...
July 2017: Applied Spectroscopy
Xunchen Liu, Inseok Chae, Naresh Miriyala, Dongkyu Lee, Thomas Thundat, Seonghwan Kim
Broadband mid-infrared molecular spectroscopy is essential for detection and identification of many chemicals and materials. In this report, we present stand-off mid-infrared spectra of 1,3,5-trinitro-1,3,5-triazine or cyclotrimethylene trinitramine (RDX) residues on a stainless-steel surface measured by a broadband external cavity quantum cascade laser (QCL) system. The pulsed QCL is continuously scanned over 800 cm(-1) in the molecular fingerprint region and the amplitude of the reflection signal is measured by either a boxcar-averager-based scheme or a lock-in-amplifier-based scheme with 1 MHz and 100 kHz quartz crystal oscillators...
July 2017: Applied Spectroscopy
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