Cavity ring down spectrometry for disease diagnostics using exhaled air
In this paper we report the current stage of the development of a cavity ring-down spectrometer (CRDS) system using exhaled human breath analysis for the diagnostics of different diseases like diabetes and later lung cancer. The portable CRDS system is made in ultraviolet spectral region using Nd:Yag laser 266 nm pulsed light. Calibration of the CRDS system was performed using generated samples by KinTek automated permeation tube system and self-prepared mixtures with known concentration of benzene and acetone in air. First experiments showed that the limits of detection for benzene and acetone are several tens of ppb.
<title>High-frequency electrodeless light sources for application</title>
The high-frequency electrodes light sources (HFELS) are widely used as bright radiators of narrow and intensive spectral lines covering spectral region from VUV to IR. In this work we shall give a short overview of our experience in preparation of HFELS, containing He, H, Rb, Hg, Zn, Pb, As, Sb, Bi, Tl, Hg-Cd, Hg-Zn, Hg-Cd-Zn, Se-Te for different applications. Special attention would be paid for HFELS use in Zeeman mercury analyzer, in Atomic absorption analyzer and Angle and glass refractive index measurement system.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
High-frequency electrodeless lamps in argon–mercury mixtures
In this paper, numerical and experimental investigations of high-frequency (HF) electrodeless lamps in argon–mercury mixtures are performed. The intensities of the mercury spectral lines having wavelengths λ = 404.66, 435.83, 546.07 nm (7 3S1–6 3P0,1,2) and the resonance line λ = 253.7 nm (6 3 P1–6 1S0) are measured at a wide range of mercury pressures, varying the HF generator current and argon filling pressure. A stationary self-consistent model of HF electrodeless discharge lamp is developed including kinetics of the excited mercury and argon atomic states. Based on the developed model, the radiation characteristics of the discharge plasma are calculated. Numerical simulation of the line…
MATHEMATICAL MODELLING OF THE SPECTRAL LINE PROFILES IN THE HIGH-FREQUENCY DISCHARGE
Abstract The paper is devoted to an estimation of the true profiles of spectral lines and equipment influence based on complex experimental line shape profiles in high-frequency discharge by means of a non-linear multiparameter chi-square fit. The self-absorption and energy transfer effects are taken into consideration. A good agreement with interferometric data from Hg and Hg–Cd high-frequency electrodeless lamps of both natural and isotopic abundance are achieved. The temperature of radiating atoms and the optical density for several lines are obtained as a function of the high-frequency oscillator working regime. The confidence regions, standard deviations and correlations of parameters …
Investigation of Hg resonance 184.9nm line profile in a low-pressure mercury–argon discharge
Abstract The line profiles of 184.9 nm Hg resonance line emitted from a Hg low-pressure high-frequency electrodeless discharge lamp, containing Hg 198 isotope, have been measured by means of a Zeeman scanning spectrometer at the mercury cold spot temperature values in the range of 0–23 °C. Two different methods were used to determine the real spectral line profile and to separate the instrument function: (i) solving the ill-posed inverse problem by means of the Tikhonov's regularization method; and (ii) the mathematical modelling by means of a non-linear multi-parameter chi-square fit. The real Hg 184.9 nm spectral line profiles, determined by both methods, are compared. Influence of instru…
Electrodeless HF-lamps as UV and VUV light sources
The paper is devoted to problems of employment of high- frequency electrodeless lamps as ultra violet (UV) and vacuum ultra violet (VUV) light sources. Some aspects of lamp preparation technology for UV and VUV are considered. The technology, developed in our laboratory, allows to prepare HFEL-s filled with wide spread of chemical elements. Our experience shows that most important filling elements for UV and VUV spectral regions are Zn, Cd, Hg, Se, As, Sn and Pb, Sb, Bi, Tl, Te, I, H, Hg-Cd, Hg-Zn, Se-Te. The requirements for generators are discussed. Some important spectral characteristics of lamp examples are presented.
Deconvolution of Multiple Spectral Lines Shapes by Means of Tikhonov’s Regularization Method
We present deconvolution of multiple narrow Zeeman split Hg lines, emitted from Hg/Xe micro-size capillary and measured by the Fourier Transform spectrometer. The ill-posed inverse problem was solved using the Tikhonov& rsquo;s regularization method.
Study of Inductive Coupled Hydrogen and Argon Plasma Interaction with SiO2 Glass
This work is devoted to the diagnostics of interaction between hydrogen and argon with the surface of SiO2 glass walls. For diagnostics of the interaction, special high-frequency electrodeless light sources were prepared, filled with pure argon of 1 Torr or argon-hydrogen of total pressure of 1 Torr (Ar/H2 mixing ratio is 9:1). Besides the mostly used spherical and cylindrical lamps, dumbbell type lamps have also been investigated. The spectroscopic and AFM measurements showed that in comparison with pure argon plasma, the argon-hydrogen plasma causes non-uniform changes of the SiO2 surface. For these modifications active OH are primarily responsible molecules, created in the reactions of h…
Study of As and Tl high-frequency electrodeless lamps for Zeeman absorption spectroscopy
High-frequency electrodeless light sources are known as bright radiators with the line spectrum, characterized by high intensities and narrow line shapes. The lamp balloons are mostly made of quartz and filled with a metal and buffer gas. These light sources must be optimized for each application in accordance with the specific requirements of radiation quality, lifetime, and stability. This work is devoted to the diagnostic of high-frequency electrodeless light sources for their use in high precision atomic absorption analyzers and other applications like disinfection. The spectral line intensities and profiles were studied in discharges with arsenic and thallium fillings. Special attentio…
Tomographic diagnostics of high-frequency electrodeless lamps in argon–mercury mixtures
Tomographic reconstruction of spatial profiles of the mercury atom density in the excited state 7 3S1 in high-frequency electrodeless lamps (HFELs) has been performed. The measurements of the Hg 546.1 nm line emission intensity have been made for the HFELs in argon–mercury mixture depending on the operation regime with different cold spot temperatures in the range 31–98 °C. The maximum entropy-based algorithm was applied for the reconstruction of local emission coefficients from the integrated intensities. The emission coefficients are directly related to the local values of the mercury atom density in the excited state 7 3S1, the upper state of the 546.1 nm transition. Such an investigatio…
Multicomponent line profile restoring by means of ill-posed inverse task solution
The investigation of the criteria of usage of the Tikhonov regularization method for multicomponent overlapping line profiles restoring was done by means of model task solution. The influence of the width and kind of the instrumental function, number of the components of the profile and distance between components are discussed.
High-frequency electrodeless discharge lamps for atomic absorption analysis
Abstract In this paper we present the results of an investigation of high-frequency electrodeless discharge lamps (HFEDLs), containing Cd, Zn, Hg, As, Te, Se, Pb, Sn, Tl and Bi, developed in our laboratories as light sources for atomic absorption spectrometry (AAS). Important physical processes in the lamps are discussed. Essential characteristics of HFEDLs for AAS, such as intensity, stability and operating life are considered. The intensities and detection limits are compared with the corresponding characteristics of hollow cathode lamps. The temporal behavior of an As HFEDL is compared with that of a commercially available electrodeless discharge lamp. Detection limits in graphite furnac…
Radial properties of high-frequency electrodeless lamps in argon–mercury mixtures
Radial emission properties of high-frequency electrodeless discharge lamps (HFEDLs) in argon–mercury mixtures are investigated both numerically and experimentally. The radial profile of the intensities of the mercury triplet lines 404.7, 435.8 and 546.1 nm are measured for two different values of the high frequency generator power. A model describing physical processes in an HFEDL, including the calculation of radial plasma parameters, is developed. Radial intensity dependences of the lines 404.7, 435.8 and 546.1 nm are calculated and are found to be in good agreement with the experimental measurements.
Line Shape Measurement and Modelling for Plasma Diagnostics
In this paper we discuss different methods of narrow spectral line shape measurements for a wide spectral range by means of high-resolution spectrometers such as the Fabry-Perot spectrometer, Zeeman spectrometer and Fourier transform spectrometer as well as a theoretical model for spectral line shape modelling and solving of the inverse task based on Tikhonov's regularization method. Special attention is devoted to the line shape measurements for the optically thin light sources filled with Hg, Ar, Xe, Kr for their use in high precision analysers for detection of heavy metals and benzene.
Study of the High-Frequency Inductive Coupled Discharge Plasma Interaction with Walls
The high-frequency electrodeless light sources (HFELS) are widely used as bright radiators of narrow and intense spectral lines covering the region from VUV to IR. Special HFELS filled with pure helium at pressures from 0.2 to 5 Torr were prepared for diagnostics of interaction between the filling element and the wall material (glass). Pollution of the discharge plasma with the oxygen admixture was studied by spectroscopy. Atomic force microscopy experiments were performed to find modification of the wall surface at the nanoscale level. Release of oxygen by the walls is found to depend strongly on the discharge conditions and significant changes of the surface structure are detected after p…
Use of radiation sources with mercury isotopes for real-time highly sensitive and selective benzene determination in air and natural gas by differential absorption spectrometry with the direct Zeeman effect.
A new analytical portable system is proposed for the direct determination of benzene vapor in the ambient air and natural gas, using differential absorption spectrometry with the direct Zeeman effect and innovative radiation sources: capillary mercury lamps with different isotopic compositions ((196)Hg, (198)Hg, (202)Hg, (204)Hg, and natural isotopic mixture). Resonance emission of mercury at a wavelength of 254 nm is used as probing radiation. The differential cross section of benzene absorption in dependence on wavelength is determined by scanning of magnetic field. It is found that the sensitivity of benzene detection is enhanced three times using lamp with the mercury isotope (204)Hg in…
Validation of the solution method using Tikhonov regularization algorithm for spectral line diagnostics of microsize plasma
This paper is devoted obtaining the threshold of the credibility of the solution by means of Tikhonov's regularization method in case of spectral lines, emitted from microsize plasma sources. The reliability of Tikhonov algorithm was verified by means of solving model tasks with different ratio between instrumental function and measured profile and, with different levels of noise.
First results of cavity ring down signals from exhaled air
In this paper we report first results from the developed cavity ring-down spectrometer for application in human breath analysis for the diagnostics of diabetes and later for early detection of lung cancer. Our cavity ring-down spectrometer works in UV region with pulsed Nd:YAG laser at 266 nm wavelength. First experiments allow us to determine acetone and benzene at the level bellow ppm. In our experiment, first results from breath samples from volunteers after doing different activities were collected and examined. Influence of the smoking on the breath signals also was examined.
Light source inner surface changes depending on treatment
Our work is connected with the preparation of different type of electrodeless discharge lamps. In this work we investigate the influence of the SiO2 glass wall treatment procedures on the inner surface of the electrodeless lamps. Three different treatment procedures were applied: vacuum cleaning, vacuum-thermal cleaning and training in the high frequency discharge. The surface modification has been investigated by means of atomic force microscopy. Substantial changes of the SiO2 glass surface have been observed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Diagnostics of capillary light sources by means of line shape measurements and modeling
In this work the Hg visible triplet spectral lines were measured by means of Fourier Transform spectrometer and deconvoluted by Tikhonov's regularisation method and line shape modelling. The lines were collected from Hg/Ar and Hg/Xe high frequency capillary lamps. In our previous work, the spatial plasma homogeneity of isotope Hg/Xe and Hg/Ar capillary lamps was investigated by means of tomography. The lamps were operated in different working positions – horizontally and vertically. In this work the spectral diagnostics of capillary light sources by means of spectral line shape measurements and modelling is presented to obtain plasma temperature. The results are compared with the results fo…
Spatial Diagnostics of Hg/Ar and Hg/Xe Discharge Lamps by Means of Tomography
In this work, the diagnostics using tomography in Hg/Xe and Hg/Ar capillary lamps is presented. First, the imaging of the lamps was performed using selected emission lines of mercury, argon and xenon in different operation conditions. Thus the tomographic reconstruction was made, to determine the spatial distribution of the emitting Hg and rare gas atoms. Significant differences of the distribution of the emitting atoms have been found in vertical and horizontal operation positions. The emitting mercury atoms in the state 73S1 were differently distributed within the lamp in the vertical and horizontal lamp positions. The radial profile has demonstrated a substantial depletion of the popula…
Measurements of SiO2glass surface parameters by methods of microscopy
In this research we compare chemical and plasma treatment methods for surface of SiO2 glass. For chemical treatment of surface tequila and alcohol were used but for plasma treatment - Ar+As and Ar+Se plasmas. Surface topography was analyzed using atomic force microscope. Comparison of chemical and plasma treatment methods shows that surface treated with plasma is smoother. Because of their various chemical compositions tequila and alcohol show different results.
<title>Advanced light sources for atomic absorption analysis</title>
High-frequency electrodeless light sources (HF EDLS) are widely used as bright radiators of narrow and intensive atomic and ionic spectral lines, covering the spectrum from VUV to IR. Main characteristics of HF EDLS are high emitted spectral line intensity, long service life, and in general, narrow spectral line shapes because of low-pressure of filling elements. In this work we give a short overview of the use of HF EDLS, containing Hg, Te, Se, Zn, Pb, As, Sb, Bi, Tl, In, Cd, Sn, in Zeeman Atomic absorption devices for assaying natural, drinking, waste and technical water as well as air, soil, food products and biological samples. The first steps are made for optimization of Ge, Ga, P, S, …
Diagnostics of capillary mercury–argon high-frequency electrodeless discharge using line shapes
Abstract The profiles of the 253.7 nm spectral line, emitted from the capillary argon–mercury isotope high-frequency electrodeless discharge, are measured by means of a pressure-scanned Fabry–Perot spectrometer. Spectral line profiles are collected from two lamps at the argon pressure of 2 and 10 Torr, in dependence on the discharge current and Hg vapor densities corresponding to the cold spot temperatures of 25–80 °C. By means of a multi-parameter non-linear line profile fitting procedure of multiple overlapping self-reversed Voigt profiles, the temperature of the radiating atoms and the optical density were estimated. The capillary and spherical discharge conditions were compared. The opt…