Infrared optical constants of aqueous sulfate–nitrate–ammonium multi-component tropospheric aerosols from attenuated total reflectance measurements—Part I: Results and analysis of spectral absorbing features

2007 ◽  
Vol 108 (1) ◽  
pp. 17-38 ◽  
Author(s):  
Gregory J. Boer ◽  
Irina N. Sokolik ◽  
Scot T. Martin
Keyword(s):  
Optical Constants ◽  
Attenuated Total Reflectance ◽  
Total Reflectance ◽  
Tropospheric Aerosols ◽  
Reflectance Measurements

New Technique for Determining the Optical Constants of Liquids

2002 ◽  
Vol 56 (7) ◽  
pp. 928-934 ◽  
Author(s):  
C. Dale Keefe ◽  
Jason K. Pearson
Keyword(s):  
Optical Constants ◽  
Reflectance Spectrum ◽  
Strong Absorption ◽  
New Technique ◽  
Attenuated Total Reflectance ◽  
Absorption Bands ◽  
Total Reflectance ◽  
Specular Reflectance ◽  
Volatile Liquids ◽  
Atr Spectroscopy

The traditional techniques of transmission and attenuated total reflectance (ATR) spectroscopy for determining the optical constants of liquids are not practical or reliable for very strong absorption bands. Specular reflectance can be used in these cases, but for volatile liquids it is impossible to separate the reflectance spectrum of the liquid from the absorption spectrum of the vapor above the liquid. Methods using special cells have been described in the literature to prevent the liquid from evaporating. In this paper, a similar technique that makes use of traditional transmission cells is presented. It is shown that this new technique generates k(ν˜) spectra for strong absorption bands that are accurate to approximately 2%.

Accuracy and Optimization of the Two Polarization Technique for Obtaining the Optical Constants from Attenuated Total Reflection Measurements

1978 ◽  
Vol 32 (2) ◽  
pp. 160-164 ◽  
Author(s):  
Tomas Hirschfeld
Keyword(s):  
Critical Angle ◽  
Optical Constants ◽  
Incidence Angle ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Attenuated Total Reflectance ◽  
Optimum Conditions ◽  
Experimental Accuracy ◽  
Total Reflectance ◽  
Polarization Technique

The relative error of the optical constants determined by attenuated total reflectance at two polarizations and the same incidence angle is calculated as a function of the reflectance errors by a perturbation method. The variations in the error as a function of the incidence angle are then plotted for various values of the optical constants. The experimental accuracy is optimized by either shallow incidence angles and low index optics or by high index optics in the close vicinity of the critical angle. In either case, the number of reflections should be chosen to give strong attenuation. Under optimum conditions, the method gives reasonably good accuracies.

The Utilization of Ftir (Fourier Transform Infra-Red) Method Combined with Chemometrics For Authentication of Indonesian Coffee Powder

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
Firmansyah A. ◽  
Winingsih W. ◽  
Soebara Y S
Keyword(s):  
Fourier Transform ◽  
Natural Product ◽  
High Performance ◽  
Principal Component ◽  
Raw Material ◽  
Attenuated Total Reflectance ◽  
Coffee Bean ◽  
Product Analysis ◽  
Total Reflectance ◽  
And Cluster Analysis

Analysis of natural product remain challenging issues for analytical chemist, since natural products are complicated system of mixture. The most popular methods of choice used for quality control of raw material and finished product are high performance liquid chromatography (HPLC), gas chromatography (GC) and mass spectrometry (MS). The utilization of FTIR-ATR (Fourier Transform Infrared-Attenuated Total Reflectance) method in natural product analysis is still limited. This study attempts to expand the use of FTIR spectroscopy in authenticating Indonesian coffee powder.The coffee samples studied were taken from nine regions in Indonesia, namely Aceh Gayo, Flores, Kintamani, Mandheling, Papua, Sidikalang, Toraja, Kerinci and Lampung.The samples in the form of coffee bean from various regions were powdered . The next step conducted was to determine the spectrum using the FTIR-ATR (Attenuated Total Reflectance) using ZnSe crystal of 8000 resolution. Spectrum samples, then, were analyzed using chemometrics. The utilized chemometric model was the principal component analysis (PCA) and cluster analysis (CA). Based on the chemometric analysis, there are similarities between Aceh Gayo coffee with Toraja coffee, Mandailing coffee, Kintamani coffee and Flores coffee. Sidikalang coffee has a similarity to Flores coffee; Papua coffee has a similarity to Sidikalang coffee; Lampung coffee has a similarity to Sidikalang coffee, while Kerinci coffee has a similarity to Papua coffee.

Quality evaluation of tugaksheeree samples by ATR-FTIR spectroscopy using multicomponent analysis

2020 ◽  
Vol 10 ◽  
Author(s):  
Nikunj D. Patel ◽  
Niranjan S. Kanaki
Keyword(s):  
Principal Component Analysis ◽  
Cluster Analysis ◽  
Quality Evaluation ◽  
Principal Component ◽  
Hierarchical Cluster ◽  
Attenuated Total Reflectance ◽  
Chemometric Methods ◽  
Total Reflectance ◽  
Fingerprint Region ◽  
Ftir Technique

Background: Numerous Ayurvedic formulations contains tugaksheeree as key ingredient. Tugaksheereeis the starch gained from the rhizomes of two plants, Curcuma angustifoliaRoxb. (Zingiberaceae) and Marantaarundinacea (MA) Linn. (Marantaceae). Objective: The primary concerns in quality assessment of Tugaksheeree occur due to adulteration or substitution. Method: In current study, Fourier transform infrared (FTIR) technique with attenuated total reflectance (ATR) facility was used to evaluate tugaksheeree samples. Total 10 different samples were studied and transmittance mode was kept to record the spectra devoid of pellets of KBR. Further treatment was given with multi component tools by considering fingerprint region of the spectra. Multivariate analysis was performed by various chemometric methods. Result: Multi component methods like Principal Component Analysis (PCA), and Hierarchical Cluster Analysis (HCA)were used to discriminate the tugaksheeree samples using Minitab software. Conclusion: This method can be used as a tool to differentiate samples of tugaksheeree from its adulterants and substitutes.

Negatively Charged Ions to Probe Self-Assembled Monolayers Reorganization Driven by Interchain Interactions

2021 ◽  
Author(s):  
Angelo Tricase ◽  
Angela Stefanachi ◽  
Rosaria Anna Anna Picca ◽  
Eleonora Macchia ◽  
Alessandro Favia ◽  
...  
Keyword(s):  
Grazing Angle ◽  
Self Assembled Monolayers ◽  
Attenuated Total Reflectance ◽  
Interchain Interaction ◽  
Total Reflectance ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Interchain Interactions ◽  
Ir Study ◽  
Charged Ions

A combined cyclic voltammetry (CV) and grazing angle – attenuated total reflectance (GA-ATR) IR study on the interchain interaction driven reorganization of self-assembled monolayers (SAMs) in an electric field, is...

Detection of bloodstains using attenuated total reflectance-Fourier transform infrared spectroscopy supported with PCA and PCA–LDA

2021 ◽  
pp. 002580242110109
Author(s):  
Sweety Sharma ◽  
Rito Chophi ◽  
Jaskirandeep Kaur Jossan ◽  
Rajinder Singh
Keyword(s):  
Fourier Transform ◽  
Ftir Spectroscopy ◽  
Body Fluid ◽  
Due Process ◽  
Dna Analysis ◽  
Fourier Transform Infrared ◽  
Body Fluids ◽  
Attenuated Total Reflectance ◽  
Total Reflectance ◽  
Non Destructive

The most important task in a criminal investigation is to detect and identify the recovered biological stains beyond reasonable scientific doubt and preserve the sample for further DNA analysis. In the light of this fact, many presumptive and confirmatory tests are routinely employed in the forensic laboratories to determine the type of body fluid. However, the currently used techniques are specific to one type of body fluid and hence it cannot be utilized to differentiate multiple body fluids. Moreover, these tests consume the samples in due process, and thus it becomes a great limitation especially considering the fact that samples are recovered in minute quantity in forensic cases. Therefore, such limitations necessitate the use of non-destructive techniques that can be applied simultaneously to all types of bodily fluids and allow sample preservation for further analysis. In the current work, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy has been used to circumvent the aforementioned limitations. The important factors which could influence the detection of blood such as the effect of substrates, washing/chemical treatment, ageing, and dilution limits on the analysis of blood have been analysed. In addition, blood discrimination from non-blood substance (biological and non-biological in nature) has also been studied. Chemometric technique that is PCA–LDA has been used to discriminate blood from other body fluids and it resulted in 100% accurate classification. Furthermore, blood and non-blood substances including fake blood have also been classified into separate clusters with a 100% accuracy, sensitivity, and specificity. All-inclusive, this preliminary study substantiates the potential application of ATR-FTIR spectroscopy for the non-destructive identification of blood traces in simulated forensic casework conditions with 0% rate of false classification.

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