Rotational Temperature in Helium, Argon, and Oxygen Microwave-Induced Plasmas: Comparison with Translational and Solid Surface Temperatures

1989 ◽  
Vol 43 (4) ◽  
pp. 681-687 ◽  
Author(s):  
J. Alandari ◽  
A. M. Diamy ◽  
J. M. Guillerme ◽  
J. C. Legrand ◽  
R. I. Ben-Aim
Keyword(s):  
Solid Surface ◽  
Rotational Temperature ◽  
Pressure Rise ◽  
Direct Determination ◽  
Power Input ◽  
Line Broadening ◽  
Experimental Conditions ◽  
Flow Rates ◽  
Order Of Magnitude

Translational temperature ( Tg), rotational temperature of OH ( Tr), and surface temperature ( Ts are determined in helium, argon, and oxygen plasmas. Measurements are carried out at different pressures and different flow rates as a function of microwave power input by using various methods (line broadening, pressure rise, spectroscopy, thermocouple, pyrometry). The three temperatures depend on the nature of the gas (oxygen < helium > argon) and increase with power input and pressure. Results show that Tg is of the same order of magnitude as Ts. But in all experimental conditions, Tr is always higher than Tg. Therefore, Tr is inadequate for estimating Tg. When no direct determination of Tg is available, Ts seems to give a better estimation of this important parameter.

Synchronous Luminescence Spectroscopy: Methodology and Applicability

1982 ◽  
Vol 36 (5) ◽  
pp. 576-581 ◽  
Author(s):  
Tuan Vo-Dinh
Keyword(s):  
Direct Determination ◽  
Cost Effective ◽  
Luminescence Spectroscopy ◽  
Second Derivative ◽  
Experimental Conditions ◽  
Complex Samples ◽  
Figures Of Merit ◽  
Synchronous Luminescence Spectroscopy ◽  
Complex Organic

This paper discusses the figures of merit associated with the synchronous luminescence (SL) technique in multicomponent analysis of complex samples. Spectral interferences and experimental factors that influence the choice of experimental conditions are investigated. The efficacy of SL is demonstrated in the direct determination of anthracene and 2-methylanthracene in a raw coal liquid. The application of the second-derivative technique to the SL measurement of organic samples is shown. Special emphasis is directed toward the applicability of the SL technique as a practical and cost-effective screening procedure in the routine analysis of complex organic samples.

Experimental determination of the instrumental broadening in the Bragg–Brentano geometry

1994 ◽  
Vol 9 (3) ◽  
pp. 180-186 ◽  
Author(s):  
P. Scardi ◽  
L. Lutterotti ◽  
P. Maistrelli
Keyword(s):  
High Resolution ◽  
Experimental Determination ◽  
Simple Procedure ◽  
Line Broadening ◽  
Experimental Conditions ◽  
Analytical Functions ◽  
Profile Fitting ◽  
Diffraction Angle

A simple procedure was devised for the preparation of a standard KCl powder to be used for the experimental determination of the instrumental profile in the Bragg–Brentano geometry. The standard was tested on several diffractometers, and narrow Bragg reflections in the range 28°–132° were recorded adopting various experimental conditions. Profiles were modeled with analytical functions, to describe the trend of width and shape of the instrumental profile as a function of the diffraction angle. Some indications were given to perform reliable profile fitting and line broadening analysis; a high resolution setup, obtained by employing narrow slits, large goniometer radius, and a monochromator in the diffracted beam, gives narrow reflections, even though the intensity of the diffracted beam is considerably reduced. The choice of these experimental conditions, which can be achieved using the majority of the commercial instruments, leads to symmetrical profiles, even at relatively low angle (2Θ=28°), which are highly recommended for reliable profile fitting and line broadening analysis.

scholarly journals Direct determination of piroxicam in pharmaceutical forms using flow injection- spectrophotometry

2020 ◽  
Vol 34 (1) ◽  
pp. 13-23
Author(s):  
Ream Ismail Abed ◽  
Hind Hadi ◽  
Hind Hadi
Keyword(s):  
Flow Injection ◽  
Room Temperature ◽  
Direct Determination ◽  
High Sensitivity ◽  
Experimental Conditions ◽  
Spectrophotometric Methods ◽  
Relative Standard ◽  
Physical Variables ◽  
Orange Color

In this research, direct batch and flow injection (FI) spectrophotometric methods for the analysis of piroxicam (PIX) in commercial dosage forms were investigated. The methods were based on the reaction of PIX with diazotized metoclopramide in alkaline medium to form orange color product at room temperature which absorbs maximally at λmax 472 nm. Chemical and physical variables of batch and FI methods were optimized to produce high sensitivity and reproducibility. Under the optimized experimental conditions, Beer’s law was obeyed over concentration ranges from 1 - 35 and 10 - 250 μg/mL PIX with limits of detection of 0.2 and 3.4 μg/mL and limits of quantification of 0.7 and 11.4 μg/mL PIX for batch and FI procedures, respectively. The relative standard deviation (%RSD) was less than 0.7 and 2.4 for batch and FI procedures respectively with a sample throughput of 38 h-1 for FI procedure. The proposed methods can be used for the routine analysis for the assay of PIX in injections and capsules.   Bull. Chem. Soc. Ethiop. 2020, 34(1), 13-23. DOI: https://dx.doi.org/10.4314/bcse.v34i1.2

Direct determination of deuterium in untreated water and urine by NMR: application to DLW analysis

1995 ◽  
Vol 268 (5) ◽  
pp. E1018-E1026 ◽  
Author(s):  
J. T. Brenna ◽  
K. E. Yeager
Keyword(s):  
Least Squares ◽  
Time Domain ◽  
Fourier Transforms ◽  
Tap Water ◽  
Direct Determination ◽  
Average Error ◽  
Experimental Conditions ◽  
Wide Range ◽  
The Time Domain

Determination of deuterium (D) concentration in tap water and urine is demonstrated to average error approximately 0.5% (coefficient of variation) using a 400-MHz nuclear magnetic resonance (NMR) instrument. Time domain data are obtained using 0.75-ml samples in a broadband probe. Peak areas derived from absorption and magnitude mode Fourier transforms and least-squares fitting of the time domain free induction decays (FIDs) are all investigated as means to derive D concentrations from raw data. Least-squares fits using a sum of exponentially damped sinusoids, which yields estimates for the amplitude, damping constant (relaxation time), wavelength (resulting from mixing of precession and reference frequencies), and phase for each of the two components, are shown to provide the best precision for unfiltered FID. Amplitudes are proportional to the number of spins at each frequency, as analysis of untreated urine from doubly labeled water experiments yield highly linear washout data (r2 > 0.99998) for baseline-corrected log-transformed data. The procedure is general and should extend to other body fluids with minimal modifications. These data show that least-squares curve fitting is the most precise method of quantitative NMR data reduction for a wide range of experimental conditions.

A discussion on infared astronomy - Interferometric spectra of the Earth’s airglow (1.2 to 1.6 μm)

1969 ◽  
Vol 264 (1150) ◽  
pp. 163-169 ◽  
Keyword(s):  
Rotational Temperature ◽  
Visible Region ◽  
Precise Determination ◽  
Lower Atmosphere ◽  
The Earth ◽  
Chemiluminescent Reaction ◽  
Order Of Magnitude ◽  
Hydroxyl Emission ◽  
Vibration Rotation

The principal emission in the Earth ’s airglow at wavelengths between 1 and 2 μm is the Av = 2 sequence of the hydroxyl vibration-rotation bands (Gush & Vallance Jones 1955; Shemansky & Vallance Jones 1961). The hydroxyl emission, whose bands extend from the visible region to 4μm, is present in both the day and night airglow and is probably produced by the chemiluminescent reaction between atomic hydrogen and ozone (Wallace 1962) H + 0 3 - > O H (»' < 9) + 0 2. T he application of the multiplex Fourier spectroscopy to the study of this region of the pectrum (Connes & Gush 1960; Gush & Buijs 1964) has increased the resolving pow er attainable by nearly an order of magnitude, making possible the resolution of the rotational structure of the bands and allowing m ore precise determination of the rotational temperature. During the day, the brightness of the hydroxyl bands is exceeded by th at of the infrared atmospheric system of oxygen whose most intense bands are the 0-0 at 1-27 and the 0-1 at 1-58 um .G round-level observations of this system have been limited to the 0-1 band since the 0-0 band is strongly absorbed by the oxygen of the lower atmosphere (Vallance Jones & Harrison 1958).

The Direct Determination of I131 in Heterogeneous Fecal Specimens

1961 ◽  
Vol 41 (4) ◽  
pp. 380-384 ◽  
Author(s):  
Arthur F. Dratz ◽  
James C. Coberly
Keyword(s):  
Direct Determination
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