1,721,014 research outputs found
The Shell Seeker: What is the Quantity of Shell in the Lido di Venezia Sand? A Calibration DRIFTS Experiment
No full textIn this experiment students are proposed a fanciful application of the method of standard additions to evaluate the approximated amount of the shell component in a sample of sand collected on the Lido di Venezia seashore.
Several Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectra are recorded from a sand sample and after addition of known amounts of powdered shell. A peak characteristic of shells is selected and its normalized intensity plotted against the percentage of added shell powder. By means of a linear regression the initial concentration of the biogenic component of the sand is then estimated.
The proposed approach, based on a method of general validity for mixtures and holding also for impurity determination, requires students to perform DRIFT spectroscopic measurements of a powdery material, and - depending on the starting material - offers the chance to verify the influence of grain size on spectral features.
Well-known distortion effects on peak intensities and lineshapes due to sample inhomogeneities that usually make DRIFTS a poor technique for quantitative measurements are circumvented by asking students to follow a strict procedure for sample preparation.
The proposed experience can be carried out in one or two lab shifts depending whether students are asked to prepare starting powders and/ or determine the optical response curve and is designed for either undergraduate or graduate students
High Resolution Infrared Spectrum of 1,1 Difluoroethylene. Investigation on the n5 Fundamental
No full textTo See the World in a Grain of Sand: Recognizing the Origin of Sand Specimens by Diffuse Reflectance Infrared Fourier Transform Spectroscopy and Multivariate Exploratory Data Analysis
No full textThe experiment outlined in this paper exploits basic multivariate analysis (MVA) to identify in a number of diffuse reflectance infrared Fourier transform (DRIFT) spectra those corresponding to samples with similar compositions.
The object of this work is the spectroscopic study of sand samples from different locations, whose DRIFT spectra exhibit features reflecting their composition. MVA has been shown to effectively sort subsets of homogeneous specimens collected in the same area, as well as pointing out similarities in composition among sands of different origin.
This experiment is designed for graduate students and provides a practical application of both solid state spectroscopy and chemometrics. It is helpful to students already acquainted with MVA and willing to develop some spectroscopic skills or merely aiming to collect some data sets to work with. Conversely, the technique can be used by students familiar with spectroscopy who wish to investigate multivariate exploratory data analysis.
The spectra can also illustrate a discussion of the spectroscopy of minerals (ad-hoc flow-charts for the identification of the main constituents of sands through their spectral features are proposed)
An Exercise on Calibration: DRIFTS Study of Binary Mixtures of Calcite and Dolomite with Partially Overlapping Spectral Features
No full textUnlike most spectroscopic calibrations that are based on the study of well-separated features ascribable to the different components, this laboratory experience is especially designed to exploit spectral features that are nearly overlapping.
The investigated system consists of a binary mixture of two commonly occurring minerals: calcite and dolomite whose DRIFT (diffuse reflectance infrared Fourier transform) spectra present a peak at about 880 cm-1 due to the C-O out-of-plane bending mode separated by ~ 6 cm-1. Consequently, in the 870 - 890 cm-1 region of its medium- to low-resolution spectrum, any binary mixture made up of calcite and dolomite gives rise to a single feature due to the superposition of these two peaks. The wavenumbers of the peak center corresponding to mixtures with different composition are shown to be directly proportional to the mixture dolomiticity index ID = 100 * Wdolomite/ (Wcalcite + Wdolomite).
The parameters resulting from a linear fit on the measured data for twelve mixtures with ID ranging from 0 to 100 allow the determination of the composition of any binary mixture of calcite/dolomite given the wavenumber of the 870 - 890 cm-1 peak in the corresponding DRIFT spectrum.
This experience can be carried out in a single laboratory shift and allows the collection of a spectroscopic data set that can be possibly used in a discussion involving different and more conventional calibration approaches
High-resolution FTIR spectroscopy of vinyl chloride: the n4 fundamentals of the 35Cl and 37Cl isotopomers
No full textCarbonate and Silicate Abundance Indexing in Coarse-Grained River Sediments Using Diffuse Reflection Infrared Spectroscopy (DRIFTS) and Ion-Beam-Induced Luminescence (IBIL) Spectroscopies
No full textTwo different types of spectroscopic methods, namely diffuse reflection infrared spectroscopy (DRIFTS) as a vibrational spectroscopy and ion-beam-induced luminescence (IBIL) as an optical spectroscopy, have been exploited for the analysis of three sand samples collected from the Adige, Bacchiglione, and Brenta rivers (Veneto, Northern Italy) with the aim to set up a procedure for the comparison of the relative abundance of silicates, carbonates, and feldspars. By fitting the spectra, the features corresponding to different geological compounds have been identified and descriptive indexes of their relative amount have been obtained by comparing the peak area ratios
Spectroscopic-chemometric study of sands in mortars of Xth-Regio Roman domus. A comparison with nearby rivers sediments
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