The study of the magnetically tailored atmospheric pressure dc arc plasma with aerosol supply for analytical application

Preliminary studies have shown that external oscillatory magnetic fields of a few mT imposed to the atmospheric pressure DC argon arc plasma with aerosol supply, can produce significant favourable changes of its spatial and spectral characteristic. These changes are promising for improvement the analytical performance of such treated plasma. In this work, the applied magnetic fields strengths were in the range of 29- 23 mT and frequencies of 300-900 Hz. Spatial emission intensities of several element lines have been investigated in such magnetic field-plasma configuration with various plasma operating conditions and arc device construction modifications. Applied magnetic field induces lines emission intensity enhancements of the most elements observed. Enhancements (up to 20 times) depend on arc current, magnetic field strength and frequency applied, composition of sprayed solution, spatial plasma zone observed and construction detailsPhysical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Diagnostics of laser-induced plasma from a thin film of oil on a silica wafer

In this study, plasma induced by a nanosecond Nd:YAG laser on thin oil films deposited on a silica wafer was characterized by evaluating the main plasma parameters. Spatially and temporally integrated spectral measurements were performed under experimental conditions optimized for elemental analysis of trace metals in oil. Time-resolved values of the spectral line intensities, electron number density, and plasma temperature were obtained from time-integrated measurements by subtracting averaged spectra recorded at different time delays. The electron number density was estimated using the Stark broadened profile of the hydrogen Balmer alpha line. Ionization temperatures were derived from Mg ionic to atomic line intensity ratios. The obtained apparent values of time-resolved plasma parameters were in the range of 1.1×1017 cm-3 (1.5 μs) to 1.5×1016 cm-3 (4 μs) and 9400 K (3 μs) to 7200 K (5 μs), depending on the delay time. Emission spectra of C2 and CN molecules were used to evaluate the rotational and vibrational temperature

A spectroscopic investigation of stabilized dc argon arc by power modulation technique

Spatial distribution of delayed responses of argon and hydrogen spectral line and continuum intensity to square power modulation was investigated in order to get better insight into the processes occurring in argon dc arc plasma. The power was abruptly changed between stationary values, 9 and 3.5 A. For these currents steady state radial distributions of electron number density, temperature and emission intensity were measured. On part of the discharge, radial profiles the power drop and the power jump are both accompanied by intensity peaks which may be explained by displacement of the arc core axis and change in the arc core diameter during the power modulation.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Study of the spatial redistribution of the analyte spectral emission in dc arc plasma induced by external oscillating magnetic field

Monochromatic digital imaging technique was developed for studying the spatial emission intensity distribution of atmospheric pressure dc arc plasma with aerosol supply. Arc plasma was imposed to external oscillating magnetic fields of strengths up to 12 mT and frequency of 50 Hz. This plasma was studied in a laterally resolved manner and at selected observation heights. The intensity enhancement and spatial redistribution of the analyte emission was evaluated and compared to the steady state plasma. The intensity enhancements were correlated with the attained speeds of plasma core movement. Spatial regions in the arc plasma with maximal emission enhancement are identified and clarified. The effect of the electrode polarity was also investigated.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Material surface modifications by short (ns) and ultra-short (ps, fs) lasers – New Trends at VINCA Institute

Modification/processing of the material surfaces by laser radiation is modern and high precise method/technique. In the course of last decade the material modifications by short (nanosecond) and ultra-short (pico-, femto-second) lasers are especially of high interest. Laser method, among other, is non-contact (free- contamination), thermal reduced, and highly precise technique and can be applied on metals, semiconductors, ceramics, etc. Due to more convenient nature of changes on material surface the modification/processing is of high interest in industry, aero-space engineering, nuclear complex, bio-medicine, etc., nowadays. Examples of the usage of short (nanosecond) and ultra-short (pico-, femto- second) lasers, at the Institute VINCA, for irradiation of the targets such as, steels; Ti, (Ti6Al4V alloy); etc, as well as specific target in coating-substrate form, e.g. a- CN/TiAlN-ASP 30 steel, will be presented.Proceedings of the XI Belarusian-Serbian Symposium "Physics and Diagnostics of Laboratory and Astrophysical Plasmas" (РDР-11), December 15-19, Minsk, Belaru

Determination of nickel, cobalt and chromium in a soda-lime glass by using LIBS based on pulses IR laser

This work presents a study of the applicability of laser-induced breakdown spectroscopy (LIBS), based on Infrared Transversally Excited Atmospheric CO2 pulsed laser (TEA CO2), to determine nickel, cobalt, and chromium in a window glass samples. Estimated limits of detection (LODs) for Ni, Co, and Cr, were 2.1, 3.2, and 0.4 ppm, respectively. In addition, two main plasma parameters, electron number density and temperature, were determined to characterize the laser-induced plasma. The electron number density (Ne) was determined from the measured Stark width of the Al I 396.15 nm line, and the intensity ratio of two atomic iron lines (342.71 nm and 344.06 nm) was used to determine the excitation temperature (Texc). The obtained values were Ne= 8.3·1016 cm-3 and Texc= 7700 K.The book of abstracts available at: [http://www.socphyschemserb.org/media/physical-chemistry-2022/abstracts.pdf

Study of a long term processes in d.c. argon arc plasma by square power modulation with variable low current period

U-shaped d.c. argon stabilized arc with aerosol supply was investigated by current modulation between 9 and 3 A level and low current period lasting from 0.05 to 40 ms. The variable low current period has great influence on delayed line intensity response that provides information about a recombination and transport processes in plasma. The obtained results indicate that plasma slowly reaches stationary state and that processes related to changes in atom concentration play important role. Character of temporal responses strongly depends on first ionization energy of analyte.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Development of the original LIBS apparatus based on TEA CO2 laser for application in the green analytical chemistry

Spektroskopija laserski indukovane plazme (Laser Induced Breakdown Spectroscopy, LIBS) je savremena metoda hemijske analize koja koristi optički signal iz laserski generisane plazme za proučavanje sastava materijala. LIBS se može koristiti za analizu uzoraka različite prirode i porekla zbog čega je našao primenu u brojnim oblastima [1]. U oblasti zaštite životne sredine LIBS je pogodan za brzu analizu opasnih metala i drugih zagađivača u vodi, zemljištu, biljkama, vazduhu, kao i za analizu otpada. Ono što posebno izdvaja LIBS od drugih spektrohemijskih metoda je mogućnost detekcije svih hemijskih elemenata iz periodnog sistema, uključujući i lake elemente (He, Li, Be, B, C, N, O...) koji se teško određuju drugim tehnikama, analiza čvrstih uzoraka bez potrebe za pripremom uzoraka, kao i mogućnost analize u realnom vremenu (in situ, stand-off, remote). Posebno treba istaći da se LIBS uklapa u koncept zelene analitičke hemije koja je prepoznata kao ključni deo zelene hemije [2]. Razvoj zelene analitičke hemije ima za cilj smanjenje negativnog uticaja hemijskih analiza na životnu sredinu. Najvažniji izazov za budućnost ove discipline jeste postizanje kompromisa između poboljšanja kvaliteta rezultata i povećanja ekološke prihvatljivosti analitičke metode. Danas, spektroskopske metode dominiraju u oblasti zelene analitičke hemije, a među njima posebno se, svojim karakteristikama i univerzalnošću, izdvaja LIBS. U najvećoj meri LIBS ispunjava postavljene principe zelene analitičke hemije koji razmatraju kompletan analitički proces koji uključuje uzorkovanje, pripremu, kao i sam proces analize uzoraka [2,3]. LIBS karakteriše velika fleksibilnost instrumentalne postavke. U zavisnosti od željene namene, optimizacija LIBS sistema može se postići izborom lasera određene energije, vremenskog trajanja laserskog impulsa (nanosekundni, pikosekundni, femtosekudni), kao i talasne dužine zračenja (ULJ, VID, IC). U praksi uobičajeno se koristi LIBS sistem koji se sastoji iz Nd:YAG lasera, spektrometra i detektora sa vremenskom rezolucijom. U okviru Laboratorije za fizičku hemiju INN Vinča razvijena je originalna LIBS aparatura koja se bazira na TEA (Transverzalno Ekscitovanom Atmosferskom) CO2 laseru, Slika 1. Ovaj kompaktni, impulsni, nanosekundni laser, koji je takođe kompletno konstruisan u INN Vinča, radi u visoko multimodnom režimu i emituje zračenje u infracrvenom delu spektra na 10,6 µm. Analitička primena laserski indukovane plazme zahteva optimizaciju, odnosno razdvajanje intenziteta kontinualnog zračenja od intenziteta linijske emisije analita u cilju postizanja zadovoljavajućih granica detekcije za posmatrani element. Za razliku od komercijalno dostupnih LIBS aparatura u kojima se koristi vremensko razlaganje signala, u ovoj eksperimentalnoj postavci optimizacija je postignuta alternativnom metodom, korišćenjem vremenski-integraljene prostorno-razložene laserske spektroskopije. Na ovaj način izbegnuto je korišćenje generatora kašnjenja i skupih iCCD detektora. Dosadašnja istraživanja vezana za analizu različitih tipova uzoraka pokazala su da je LIBS sistem koji koristi impulsni CO2 laser po analitičkim performansama (selektivnost, osetljivost, granice detekcije) u potpunosti uporedljiv sa komercijalnim LIBS uređajima, u odnosu na koje je naš sistem znatno kompaktniji, robusniji i ekonomski isplativiji [4-6]. Kompaktnost LIBS-a je posebno značajna jer manji broj komponenti olakšava konstrukciju prenosivog LIBS uredjaja. Tekuća istraživanja usmerena su na optimizaciju TEA CO2 LIBS-a za detekciju zagađenja vode i zemljišta teškim metalima.8th Symposium Chemistry and Environmental Protection : May 30 - June 1, Kruševac, 2018

Desorption of metals from Cetraria islandica (L.) Ach. Lichen using solutions simulating acid rain

Desorption of metals K, Al, Ca, Mg, Fe, Ba, Zn, Mn, Cu and Sr from Cetraria islandica (L.) with solutions whose composition was similar to that of acid rain, was investigated. Desorption of metals from the lichen was performed by five successive desorption processes. Solution mixtures containing H2SO4, HNO3 and H2SO4-HNO3 were used for desorption. Each solution had three different pH values: 4.61, 5.15 and 5.75, so that the desorptions were performed with nine different solutions successively five times, always using the same solution volume. The investigated metals can be divided into two groups. One group was comprised of K, Ca and Mg, which were desorbed in each of the five desorption processes at all pH values used. The second group included Al, Fe, Zn, Ba, Mn and Sr; these were not desorbed in each individual desorption and not at all pH values, whereas Cu was not desorbed at all under any circumstances. Using the logarithmic dependence of the metal content as a function of the desorption number, it was found that potassium builds two types of links and is connected with weaker links in lichen. Potassium is completely desorbed, 80% in the first desorption, and then gradually in the following desorptions. Other metals are linked with one weaker link (desorption 1-38%) and with one very strong link (desorption below the metal detection limit). [Projekat Ministarstva nauke Republike Srbije, br. III43009 i br. ON 172019

The electron number density of argon-oxygen atmospheric pressure plasma

The studied plasma source was a wall stabilized directcurrent arc burning in argon at atmospheric pressure, originally designed for elemental spectrochemical analysis.The influence of oxygenaddition (1 -20 %) on the electron density of mixed gas plasmawas investigated for two initial plasma compositions, i.e.argon gas with water aerosol and and argon with water aerosol containing 0.5 % KCl. The electron number densitieswerecalculated from themeasured Stark profiles of Hβspectral line. The results have shown that the addition of oxygenhas weak influence on electron number density in the studied central plasma zones. Similar trends were observed regardless of the presence or absence of easily ionized element (potassium).Physical chemistry 2016 : 13th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-30 September 2016