254,784 research outputs found
SR-FTiR microscopy and FTIR imaging in the earth sciences
During the last decades, several books have been devoted to the application
of spectroscopic methods in mineralogy. Several short courses and meetings have
addressed particular aspects of spectroscopy, such as the analysis of hydrous
components in minerals and Earth materials. In these books, complete treatment
of the infrared theory and practical aspects of instrumentation and methods,
along with an exhaustive list of references, can be found. The present chapter
is intended to cover those aspects of infrared spectroscopy that have been
developed in the past decade and are not included in earlier reviews such as
Volume 18 of Reviews in Mineralogy. These new topics involve primarily: (1) the
use of synchrotron radiation (SR), which, although not a routine method, is now
rather extensively applied in infrared studies, in particular those requiring
ultimate spatial and time resolution and the analysis of extremely small
samples (a few tens of micrometers); (2) the development of imaging techniques
also for foreseen time resolved studies of geo-mineralogical processes and
environmental studies.Comment: 36 pages, 24 figures - Reviews in Mineralogy & Geochemistry - Vol. 78
(2013) in pres
Evaluation of a FTIR Emission Measurement System for Legislated Emissions Using a SI Car
A series of chassis dynamometer test trials were
conducted to assess the performance of a Fourier
Transform Infra Red (FTIR) system developed for
on-road vehicle exhaust emissions measurements.
Trials used a EURO 1 emission compliant SI passenger
car which, alongside the FTIR, was instrumented to
allow the routine logging of engine speed, road speed,
throttle position, air-fuel ratio, air flow and fuel flow in
addition to engine, exhaust and catalyst temperatures.
The chassis dynamometer facility incorporated an
‘industry standard’ measurement system comprising
MEXA7400 gas analyzer and CVS bag sampling which
was the ‘benchmark’ for the evaluation of FTIR
legislated gas-phase emissions (CO, NOx, THC and
CO2) measurements.
Initial steady state measurements demonstrated strong
correlations for CO, NOx and THC (R2 of 0.99, 0.97
0.99, respectively) and a good correlation for CO2 (R2 =
0.92). Subsequent transient and total mass emissions
measurements from replicate samplings of four different
driving cycles (two standard cycles, FTP75 and NEDC,
and two novel cycles based on real-world data collected
in Leeds) also show good response of FTIR and
satisfied agreement between the FTIR and CVS bag
sampling measurements.
In general, the trial results demonstrate that the
on-board FTIR emission measurement system provides
reliable in-journey emissions data
Application of a portable FTIR for measuring on-road emissions
The objective of this work was the development of an onroad
in-vehicle emissions measurement technique
utilizing a relatively new, commercial, portable Fourier
Transform Infra-Red (FTIR) Spectrometer capable of
identifying and measuring (at approximately 3 second
intervals) up to 51 different compounds. The FTIR was
installed in a medium class EURO1 spark ignition
passenger vehicle in order to measure on-road
emissions. The vehicle was also instrumented to allow
the logging of engine speed, road speed, global position,
throttle position, air-fuel ratio, air flow and fuel flow in
addition to engine, exhaust and catalyst temperatures.
This instrumentation allowed the calculation of massbased
emissions from the volume-based concentrations
measured by the FTIR. To validate the FTIR data, the
instrument was used to measure emissions from an
engine subjected to a real-world drive cycle using an AC
dynamometer. Standard analyzers were operated
simultaneously for comparison with the FTIR and the
standard analyzer results showed that most pollutants
(NOx, CO2, CO) were within ~10% of a standard analyzer
during steady state conditions and within 20% during
transients. The exception to this was total HC which was
generally 50% or less than actual total HC, but this was
due to the limited number of hydrocarbons measured by
the FTIR. In addition to the regulated emissions, five
toxic hydrocarbon species were analyzed and found to
be sensitive to cold starts in varying proportions. Finally,
FTIR data was compared to results from a commercially
available on-road measurement system (Horiba OBS-
1000), and there was good agreement
ATR-FTIR Spectroscopic Analysis of Sorption of Aqueous Analytes into Polymer Coatings Used with Guided SH-SAW Sensors
Attenuated total internal reflectance Fourier transform infrared (ATR-FTIR) spectroscopy was used for the investigation of sorption of aqueous solutions of analytes into polymer coatings. A series of simple model polymers, such as poly(dimethylsiloxane), poly(epichlorhydrin), and poly(isobutylene), and films and analytes, such as aqueous solutions of ethylbenzene, xylenes, toluene, and nitrobenzene, were used to evaluate the use of ATR-FTIR spectroscopy as a screening tool for sensor development. The ratios of integrated infrared absorption bands provided a simple and efficient method for predicting trends in partition coefficients. Responses of polymer-coated guided shear horizontal surface acoustic wave (SH-SAW) sensor platforms to the series of analytes, using polymer coatings with similar viscoelastic properties, were consistent with ATR-FTIR predictions. Guided SH-SAW sensor responses were linear in all cases with respect to analyte concentration in the tested range. Comparison of ATR-FTIR data with guided SH-SAW sensor data identifies cases where mass loading is not the dominant contribution to the response of the acoustic wave sensor. ATR-FTIR spectra of nitrobenzene, coupled with computational chemistry, provided additional insight into analyte/polymer interactions
FTIR analysis of aviation fuel deposits
Five modes of operation of the Nicolet 7199 Fourier Transform Infrared Spectrophotometer have been evaluated for application in analysis of the chemical structure of accelerated storage/thermal deposits produced by jet fuels. Using primarily the absorption and emission modes, the effects of fuel type, stress temperature, stress time, type of spiking agent, spiking agent concentration, fuel flow, and post-depositional treatment on the chemical nature of fuel deposits have been determined
Melting of Single Lipid Components in Binary Lipid Mixtures: A Comparison between FTIR Spectroscopy, DSC and Monte Carlo Simulations
Monte Carlo (MC) Simulations, Differential Scanning Calorimetry (DSC) and
Fourier Transform InfraRed (FTIR) spectroscopy were used to study the melting
behavior of single lipid components in two-component membranes of
1,2-Dimyristoyl-D54-sn-Glycero-3-Phosphocholine (DMPC-d54) and
1,2-Distearoyl-sn-Glycero-3-Phosphocholine (DSPC). Microscopic information on
the temperature dependent melting of the single lipid species could be
investigated using FTIR. The microscopic behavior measured could be well
described by the results from the MC simulations. These simulations also
allowed to calculate heat capacity profiles as determined with DSC. These ones
provide macroscopic information about melting enthalpies and entropy changes
which are not accessible with FTIR. Therefore, the MC simulations allowed us to
link the two different experimental approaches of FTIR and DSC.Comment: 12 pages, 5 figures, corrected typo in table 1 in which previously it
said Tm,1 instead of Tm,
A TGA/FTIR and Mass Spectral Study on the Thermal Degradation of Bisphenol A Polycarbonate
The thermal degradation of polycarbonate under nitrogen was studied using TGA/FTIR, GC/MS and LC/MS as a function of mass loss. The gases evolved during degradation were inspected by in situ FTIR and then the evolved products were collected and analysed using FTIR, GC–MS and LC–MS. The structures of the evolved products are assigned on the basis of FTIR and GC/MS results. The main thermal degradation pathways follow chain scission of the isopropylidene linkage, and hydrolysis/alcoholysis and rearrangement of carbonate linkages. In the case of chain scission, it was proposed that methyl scission of isopropylidene occurs first, according to the bond dissociation energies. The presence of carbonate structures, 1,1′-bis(4-hydroxyl phenyl) ethane and bisphenol A in significant amounts, supports the view that chain scission and hydrolysis/alcoholysis are the main degradation pathways for the formation of the evolved products
HET acid based oligoesters – TGA/FTIR studies
One of the important reactive halogenated dicarboxylic acids used in the synthesis of flame retardant unsaturated polyester resins is 1,4,5,6,7,7-hexachlorobicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid (HET acid). In the present investigation four different oligoesters are synthesized using HET acid as the diacid component and 1,2-ethane diol, 1,2-propane diol, 1,3-propane diol and 1,4-butane diol as the aliphatic diols. Melt condensation technique in vacuum is used for the synthesis of the oligoesters. The number average molecular weights of the oligoesters are determined using end group analysis. The degree of polymerization is estimated to be 3–5. The structural characterization is done using FTIR and NMR (1H and 13C) techniques. In the present investigation, TGA-FTIR studies for the different oligoesters are carried out in nitrogen atmosphere. The materials are heated from ambient to 600 °C at a heating rate of 20 °C/min. The main volatile products identified are CO, HCl, H2O, CO2, hexachlorocyclopentadiene and HET acid/anhydride. The evolution profile of these materials with respect to the structure of the oligoesters is discussed in detail and presented. The importance of β-hydrogens in the diol component and the plausible mechanism for the flame retardant behavior of these oligoesters are presented
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