Instrumental Resolution Considerations for Fourier Transform Infrared Gas-Phase Spectroscopy

1997 ◽  
Vol 51 (8) ◽  
pp. 1159-1169 ◽  
Author(s):  
P. Jaakkola ◽  
J. D. Tate ◽  
M. Paakkunainen ◽  
J. Kauppinen ◽  
P. Saarinen
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Gas Phase ◽  
Dynamic Range ◽  
Fourier Transform Infrared ◽  
High Signal ◽  
Low Resolution ◽  
Instrumental Resolution ◽  
Ft Ir ◽  
Gas Phase Spectroscopy

Instrumental resolution has a significant effect on the performance of Fourier transform infrared (FT-IR) spectrometers used for gasphase analysis. Low-resolution FT-IR spectroscopy offers some valuable advantages compared with the traditional high-resolution FT-IR gas-phase spectroscopy, especially in nonlaboratory environments. First, high signal-to-noise ratio (SNR) spectra can be acquired in field conditions without the use of traditional liquid nitrogen-cooled detectors. Second, the dynamic range for quantitative analysis is larger for low-resolution spectroscopy than for high-resolution due to the lower absorbance values and lower noise levels. Third, spectral analysis speed is increased and data storage requirements are substantially reduced. The purpose of this study was to investigate the effect of instrumental resolution on FT-IR gas-phase analysis. The effects of spectral resolution on sensitivity, selectivity, accuracy, precision, spectral overlap, dynamic range, and nonlinearity are separately discussed.

scholarly journals Spectral Aerosol Optical Depth Retrievals by Ground-Based Fourier Transform Infrared Spectrometry

2020 ◽  
Vol 12 (19) ◽  
pp. 3148
Author(s):  
África Barreto ◽  
Omaira Elena García ◽  
Matthias Schneider ◽  
Rosa Delia García ◽  
Frank Hase ◽  
...  
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Cross Validation ◽  
Mineral Dust ◽  
Fourier Transform Infrared ◽  
Water Soluble ◽  
Infrared Spectrometry ◽  
Low Resolution

Aerosol Optical Depth (AOD) and the Ångström Exponent (AE) have been calculated in the near infrared (NIR) and short-wave infrared (SWIR) spectral regions over a period of one year (May 2019–May 2020) at the high-mountain Izaña Observatory (IZO) from Fourier Transform Infrared (FTIR) solar spectra. The high-resolution FTIR measurements were carried out coincidentally with Cimel CE318-T photometric observations in the framework of the Aerosol Robotic Network (AERONET). A spectral FTIR AOD was generated using two different approaches: by means of the selection of seven narrow FTIR micro-windows (centred at 1020.90, 1238.25, 1558.25, 1636.00, 2133.40, 2192.00, and 2314.20 nm) with negligible atmospheric gaseous absorption, and by using the CE318-AERONET’s response function in the near-coincident bands (1020 nm and 1640 nm) to degrade the high-resolution FTIR spectra. The FTIR system was absolutely calibrated by means of a continuous Langley–Plot analysis over the 1-year period. An important temporal drift of the calibration constant was observed as a result of the environmental exposure of the FTIR’s external optical mirrors (linear degradation rate up to 1.75% month−1). The cross-validation of AERONET-FTIR databases documents an excellent agreement between both AOD products, with mean AOD differences below 0.004 and root-mean-squared errors below 0.006. A rather similar agreement was also found between AERONET and FTIR convolved bands, corroborating the suitability of low-resolution sunphotometers to retrieve high-quality AOD data in the NIR and SWIR domains. In addition, these results demonstrate that the methodology developed here is suitable to be applied to other FTIR spectrometers, such as portable and low-resolution FTIR instruments with a potentially higher spatial coverage. The spectral AOD dependence for the seven FTIR micro-windows have been also examined, observing a spectrally flat AOD behaviour for mineral dust particles (the typical atmospheric aerosols presented at IZO). A mean AE value of 0.53 ± 0.08 for pure mineral dust in the 1020–2314 nm spectral range was retrieved in this paper. A subsequent cross-validation with the MOPSMAP (Modeled optical properties of ensembles of aerosol particles) package has ensured the reliability of the FTIR dataset, with AE values between 0.36 to 0.60 for a typical mineral dust content at IZO of 100 cm−3 and water-soluble particle (WASO) content ranging from 600 to 6000 cm−3. The new database generated in this study is believed to be the first long-term time series (1-year) of aerosol properties generated consistently in the NIR and SWIR ranges from ground-based FTIR spectrometry. As a consequence, the results presented here provide a very promising tool for the validation and subsequent improvement of satellite aerosol products as well as enhance the sensitivity to large particles of the existing databases, required to improve the estimation of the aerosols’ radiative effect on climate.

The high-resolution Fourier transform infrared spectrum of isocyanogen, CNCN: rovibrational analysis of the ν1 and ν2 stretching band systems

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1251-1264 ◽  
Author(s):  
F. Stroh ◽  
M. Winnewisser ◽  
B. P. Winnewisser
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Infrared Spectrum ◽  
Gas Phase ◽  
Fourier Transform Infrared ◽  
Rotational Constant ◽  
Spectroscopic Constants ◽  
Linear Molecule ◽  
Effective Hamiltonian ◽  
Valence Force

The high-resolution gas phase Fourier transform infrared spectrum of the linear molecule isocyanogen, CNCN, has been measured in the 2000–2400 cm−1 region. The C≡N stretching band systems ν1 and ν2 located around 2302.0 and 2059.7 cm−1, respectively, were observed with an unapodized resolution of 0.003 cm−1. In the analysis of these band systems hot bands originating from the states with up to 3 quanta of ν5, the singly excited ν4, and the combination state (ν4 ν5) = (11) were assigned. Effective spectroscopic constants of the numerous subbands as well as constants of an effective Hamiltonian are presented. An analysis of rotation–vibration interaction in CNCN as well as a complete valence force field are presented. The equilibrium rotational constant Be of CNCN was found to be 5172.66 (18) MHz, the diagonal valence force constants determined for C=N–C≡N are for the Σ modes (in aJ/Å2): fC=N− = 15.1, f=N−C≡ = 8.3, f−C=N = 17.1, and for the Π modes (in aJ): fC=N−C≡ = 0.141, f=N−C≡N = 0.361.

Forensic Drug Identification, Confirmation, and Quantification Using Fully Integrated Gas Chromatography with Fourier Transform Infrared and Mass Spectrometric Detection (GC-FT-IR-MS)

2018 ◽  
Vol 72 (5) ◽  
pp. 750-756 ◽  
Author(s):  
Adam Lanzarotta ◽  
Lisa Lorenz ◽  
Sarah Voelker ◽  
Travis M. Falconer ◽  
JaCinta S. Batson
Keyword(s):  
Gas Chromatography ◽  
Fourier Transform ◽  
High Performance ◽  
Dynamic Range ◽  
Fourier Transform Infrared ◽  
Mass Spectrometric ◽  
Mass Spectrometric Detection ◽  
Fully Integrated ◽  
Drug Substances ◽  
Ft Ir

This manuscript is a continuation of a recent study that described the use of fully integrated gas chromatography with direct deposition Fourier transform infrared detection and mass spectrometric detection (GC-FT-IR-MS) to identify and confirm the presence of sibutramine and AB-FUBINACA. The purpose of the current study was to employ the GC-FT-IR portion of the same instrument to quantify these compounds, thereby demonstrating the ability to identify, confirm, and quantify drug substances using a single GC-FT-IR-MS unit. The performance of the instrument was evaluated by comparing quantitative analytical figures of merit to those measured using an established, widely employed method for quantifying drug substances, high performance liquid chromatography with ultraviolet detection (HPLC-UV). The results demonstrated that GC-FT-IR was outperformed by HPLC-UV with regard to sensitivity, precision, and linear dynamic range (LDR). However, sibutramine and AB-FUBINACA concentrations measured using GC-FT-IR were not significantly different at the 95% confidence interval compared to those measured using HPLC-UV, which demonstrates promise for using GC-FT-IR as a semi-quantitative tool at the very least. The most significant advantage of GC-FT-IR compared to HPLC-UV is selectivity; a higher level of confidence regarding the identity of the analyte being quantified is achieved using GC-FT-IR. Additional advantages of using a single GC-FT-IR-MS instrument for identification, confirmation, and quantification are efficiency, increased sample throughput, decreased consumption of laboratory resources (solvents, chemicals, consumables, etc.), and thus cost.

FR-IR Molecular Microanalysis System

1990 ◽  
Vol 48 (2) ◽  
pp. 270-271
Author(s):  
John A. Reffner ◽  
William T. Wihlborg
Keyword(s):  
Fourier Transform ◽  
Fourier Transform Infrared ◽  
Integrated System ◽  
Morphological Examination ◽  
Fully Integrated ◽  
Ir Microscopy ◽  
Normal Functions ◽  
Infrared Microspectroscopy ◽  
Infrared Spectral ◽  
Ft Ir

The IRμs™ is the first fully integrated system for Fourier transform infrared (FT-IR) microscopy. FT-IR microscopy combines light microscopy for morphological examination with infrared spectroscopy for chemical identification of microscopic samples or domains. Because the IRμs system is a new tool for molecular microanalysis, its optical, mechanical and system design are described to illustrate the state of development of molecular microanalysis. Applications of infrared microspectroscopy are reviewed by Messerschmidt and Harthcock.Infrared spectral analysis of microscopic samples is not a new idea, it dates back to 1949, with the first commercial instrument being offered by Perkin-Elmer Co. Inc. in 1953. These early efforts showed promise but failed the test of practically. It was not until the advances in computer science were applied did infrared microspectroscopy emerge as a useful technique. Microscopes designed as accessories for Fourier transform infrared spectrometers have been commercially available since 1983. These accessory microscopes provide the best means for analytical spectroscopists to analyze microscopic samples, while not interfering with the FT-IR spectrometer’s normal functions.

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