Green synthesis of nanoparticles: Pulsed Laser Ablation in Liquids

Laser ablation synthesis in liquid solution (PLAL) is a green technique that allows for the physical formation of ultrapure nanomaterials. In this work, Ag and Au nanoparticles are synthesized by PLAL using two different neodymium-doped yttrium aluminum garnet (Nd:YAG) laser systems. A pure silver/gold target (99.998% purity) was immersed in Milli-Q water and the sample surface of approximately 1 cm2 in size was continually scanned by a pulsed laser beam to achieve a homogenous ablation. Obtained suspensions were analyzed by ICP-OES, UV-Vis, TEM, and DLS. UV-Vis spectra showed characteristic peaks at 428 nm and 525 nm, which correlate with silver and gold nanoparticles' surface plasmon absorbance. ICP-OES analysis confirmed that these suspensions are free from impurities. Since no stabilizer is added, these nanoparticles tend to agglomerate in time, as TEM and DLS analysis confirmed (Figure 1). Nevertheless, these nanoparticles can be easily functionalized with a variety of ligands such as small molecules, surfactants, dendrimers, polymers, and biomolecules to get desirable functionalities for various applications

Interaction of impulse TEA CO2 laser radiation with copper target: spectroscopy of plasma and morphological effects

Physical chemistry / hysical chemistry - spectroscopy and Physical chemistry - material scienceОбласт проучавања ове дисертације је интеракција ласерског зрачења са металима. Ова актуелна научна област, значајна је како због бољег разумевања сложених процеса до којих долази приликом ове интеракције, тако и због бројних могућих примена. Предмет проучавања ове дисертације је интеракција зрачења импулсног наносекундног угљендиоксидног ласера са бакарном метом. Бакар је изабран као мета због великог значаја коју овај метал и његове легуре имају у савременим технологијама. Поред тога, у литератури нема података о индуковању плазме на бакру под дејством зрачења чији су интензитети реда величине од 30 до 110 MW cm-2, што је представљало својеврстан научни изазов. Циљ ове дисертације је, пре свега, проналажење оптималних експерименталних услова за стварање ласерски индуковане плазме под дејством зрачења импулсног TEA CO2 ласера на бакарну мету. Испитан је утицај стања површине мете, начина фокусирања ласерског зрачења, састава (азот, аргон, хелијум и ваздух) као и притиска (од 0,1 mbar до 1013 mbar) околног гаса на услове за стварање плазме. Спектрална емисија ласерски индуковане плазме проучавана је методом временски-интеграљене просторно-разложене оптичке емисионе спектроскопије. Посебна пажња посвећена је спектрoскопији плазме индукованој у атмосфери ваздуха. Показало се да се оптимални услови за стварање плазме постижу повећањем храпавости површине мете, постављањем мете +1,5 cm изван фокуса и снижавањем притиска ваздуха на 0,1 mbar. Резултати добијени у овој тези показали су да се посматрањем емисије из одређених зона плазме (на одређеним растојањима од површине мете) може постићи добар однос линије према позадини и линије према шуму и без временског разлагања сигнала. Ово је значајно са становишта поједностављења експерименталне технике.Такође, резултати показују да плазма индукована при коришћеним експеримeнталним условима има повољне карактеристике за спектрохемијску примену, јер се емисиони спектар састоји од добро разложених, оштрих и интензивних линија и континуалног зрачења врло ниског интензитета. Овакав закључак потврђују и границе детекције које су одређене за елементе присутне у траговима у узорцима бакра и месинга, а које су биле у опсегу 10 ppm. У овој тези проучаване су и морфолошке промена на бакарној мети које настају под дејством зрачења TEA CO2 ласера. Један мањи део истраживања урађен је коришћењем фемтосекундног титан-сафирног ласера, при чему је интензитет ласерског зрачења био у опсегу од 1012 до 1015 MW cm-2. За карактеризацију површине узорка пре и након озрачивања коришћене су различите технике: оптичка и електронска микроскопија, као и профилометрија. Дејство наносекундног ласера огледа се у формирању релативно глатких региона који су условљени топљењем бакра као и у хемијским променама на површини мете. Са порастом броја акумулираних импулса укупан ефекат добијен озрачивањем наносекундним ласерским зрачењем је “чишћење” мете, које може бити од значаја за примену у електроници. Дејство фемтосекундног ласера карактерише појава периодичних површинских структура што може имати значајну примену у оптици и електроници, нарочито у фотолитографији.This thesis is devoted to studies of the interaction of intense laser pulses with metal targets. This advanced area of research is essential for better understanding of the complex processes that occur during interaction of laser radiation with metal surfaces, and also because of a number of useful applications. The subject of research of this thesis is the interaction of a nanosecond carbon dioxide laser pulses with a copper target. The copper was selected as a target material because of a great importance of this metal and his alloys in advanced technologies. In addition, in the literature there is a lack of data concerning creation of copper plasma by using the laser pulses of low/moderate intensity. Thus, generation of copper plasma using laser peak intensities in the range of 30 to 110 MW cm-2 was a motivating task. The main aim of these investigations was to find optimal experimental conditions for the generation of plasma during irradiation of a copper target with TEA CO2 laser pulses. The influence of target surface state, focusing conditions, composition (nitrogen, argon, helium, air) and pressure (0.1 to 1013 mbar) of the surrounding atmosphere was studied. The spectral emission of laser induced plasma was studied using time-integrated spatially-resolved optical emission spectroscopy. A special attention was paid to a laser induced plasma spectroscopy studies under the ambient air. It was found that the optimal conditions for target plasma generation were obtained when targets with increased surface roughness were used, when the target was placed +1.5 cm out of the focus position, and when the air pressure was reduced to 0.1 mbar. The results have shown that good signal to noise and signal to background ratios could be obtained from emission measurements from spatially selected plasma zones, even without the use of time-gated detection. In the light of complexity of experimental setup, this result is of great importance. The emission spectra consisted of well resolved, sharp, and intense spectral lines, with very low background emission intensity. Thus, under the applied experimental conditions, the laser induced plasma has favorable characteristics for spectrochemical applications. Such conclusion was supported by the estimated limits of detection for trace elements detected in a copper and brass samples, which were in the range of 10 ppm. Morphological changes of a copper target induced by irradiation with TEA CO2 laser pulses were also studied. For these studies titanium-sapphire laser with the intensity of the laser radiation in the range 1012 to 1015 MW cm-2 was also used. For characterization of the target surface before and after the irradiation with laser light, different experimental techniques were used: optical microscopy, electron microscopy, and profilometry. The effect of nanosecond laser irradiation was the creation of relatively smooth areas caused by target melting, and also by the chemical changes of the surface. The cumulative effect of the increased number of accumulated laser pulses was some kind of surface cleaning which may find applications in electronics. The effect of femtosecond laser irradiation was appearance of periodic surface structures, which may find application in optics and electronics, especially in photolithograph

Franck-Condon factors and observed band strength distribution in the vibrational structure of the Ag_2 D-X band system

Potential curves for the X_1Σ_g^+ and D_1Σ_u^+ states of three diatomic silver isotopomers, ^(107)Ag_2, ^(107)Ag^(109)Ag and ^(109)Ag_2, were determined from the best available molecular constants by the Rydberg-Klein-Rees method. From these potentials, Franck-Condon factors and band-origin wave numbers were computed, and the reliability of the obtained values was verified by comparison with the observed band strength distribution and the measured band origin positions in a previously recorded D-X spectrum. The ratios of the Franck-Condon factors to those of corresponding isotopic bands were found to be very close to unity, revealing only a very small isotopic effect on the Franck Condon factors of Ag_2 D-X bands. The isotopic shifts of the calculated band origins agree well with previously measured displacements of band heads

Analytical capabilities of TEA CO2 laser based - LIBS setup

Laser-Induced Breakdown Spectroscopy (LIBS) has become a very popular analytical method given some of its unique features such as applicability to any type of sample, practically no sample preparation, stand-off sensing capability, speed of analysis, and a possibility to analysis even the light elements. In this paper, we present a unique laboratory LIBS setup developed in our research group. This system uses infrared TEA CO 2 laser as the excitation source and time-integrated spatially resolved (TISR) signal detection. In our recent publications, we have demonstrated the potential of using the cost- effective TEA CO 2 based LIBS system not only for the fast elemental analysis but also for the simultaneous determination of hardness of materials

Sustainable development of pressure equipment using 3d digital image correlation method

As pressure equipment is most commonly used in various industrial fields, making manufacturing processes eco-friendlier (e.g., mass reduction of the final product, material and energy savings, etc.) and transitioning to sustain-able production by developing eco-innovative products will have a positive effect on the environment. The aim of this paper is to analyze globe valve housing exposed to internal pressure using full-field experimental 3D digital image correlation (3D-DIC) method and numerical strain and stress data in order to propose improvements for more sustainable development, with respect to practical engineering application of EN standards. The highest von Mises strain values around 0.03% were measured on the point of highest geometrical discontinuity, sphere/cylinder intersection. Stresses of the examined globe valve using numerical and theoretical approach are significantly below material yield limit and allowable stress for internal pressure values of 30 bar, that is significantly higher than nominal operating pressure of 6 bar, proving that structure is over-dimensioned and can be optimized. New experimental procedure development and application in full-field strain analysis contributes to increased valve housing reliability, mass reduction and material and energy savings during manufacturing which directly affects its eco- friendliness, lowers manufacturing price and increases market competitiveness

Action of pulsed lasers on titanium target: surface effects

The interaction of lasers with metals has been studied for decades, and has been especially intensified lately, due to the development of new, efficient pulsed lasers. Titanium has a number of excellent properties, making it applicable in various modern technologies. Treatment and processing of titanium is possible with various techniques, and the application of lasers gives a special quality, such as high precision machining or obtaining specific structures on the surface which cannot be generated by other methods. During our research, surface processing of titanium was conducted by various pulsed lasers: nanosecond CO2 laser, picosecond Nd:YAG laser and femtosecond Ti: sapphire laser. In order to find the optimal conditions for surface modification of titanium, the influence of different laser parameters (wavelength, pulse duration, pulse energy, etc.), as well as the influence of the ambient, was examined. The titanium samples were irradiated in different environments, ie. in air, oxygen, nitrogen, carbon dioxide, helium and in vacuum, which affected the chemical composition and morphology of the target surface.SPIG 2022 : 31st Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers and abstracts of invited lectures, topical invited lectures and progress reports; September 5-9,2022, Belgrad

Synergy of Nd:YAG Picosecond Pulsed Laser Irradiation and Electrochemical Anodization in the Formation of TiO2 Nanostructures for the Photocatalytic Degradation of Pesticide Carbofuran

This study proposes a simple and controlled method for producing TiO2 with phase junction, oxygen vacancies, and Ti3+ by combining picosecond pulsed laser irradiation and electrochemical anodization. Ti mesh was pretreated by irradiating with a picosecond pulsed laser technique using an Nd:YAG laser (1064 nm) at two fluencies, 15 J/cm2 and 30 J/cm2 . The samples were then subjected to electrochemical anodization to form TiO2 nanotube arrays on the previously laser-treated surface. This study will investigate the possibility of forming TiO2 nanotube arrays on a pre-laser-treated Ti substrate and determine their physicochemical and photocatalytic properties. The samples were characterized by FESEM, XRD, Raman, XPS, and UV-Vis DRS. UV-Vis spectroscopy was used to observe the progress of photocatalytic degradation for all samples, and degradation products were determined using GC-MS. With the synergistic effects of phase junction, oxygen vacancies, and Ti3+, the laser-treated TiO2 with 30 J/cm2 showed a higher photocatalytic degradation rate (85.1%) of the pesticide carbofuran compared to non-laser-treated TiO2 (54.8%), remaining stable during successive degradation cycles, which has promising practical applications

Sustainable development of pressure equipment using 3D Digital Image Correlation method

As pressure equipment is most commonly used in various industrial fields, making manufacturing processes eco-friendlier (e.g., mass reduction of the final product, material and energy savings, etc.) and transitioning to sustainable production by developing eco-innovative products will have a positive effect on the environment. The aim of this paper is to analyze globe valve housing exposed to internal pressure using full-field experimental 3D digital image correlation (3D-DIC) method and numerical strain and stress data in order to propose improvements for more sustainable development, with respect to practical engineering application of EN standards. The highest von Mises strain values around 0.03% were measured on the point of highest geometrical discontinuity, sphere/cylinder intersection. Stresses of the examined globe valve using numerical and theoretical approach are significantly below material yield limit and allowable stress for internal pressure values of 30 bar, that is significantly higher than nominal operating pressure of 6 bar, proving that structure is over-dimensioned and can be optimized. New experimental procedure development and application in full-field strain analysis contributes to increased valve housing reliability, mass reduction and material and energy savings during manufacturing which directly affects its eco-friendliness, lowers manufacturing price and increases market competitiveness

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

Levels of hazardous trace elements in estuarine sediments, fish, mussels and wild boar collected from the Raša Bay area (Croatia)

A part of the Raša Bay (western Croatia) is an estuary that is fed by the sediment load from the Raša River. The local area had been affected by the former Raša coal industry. The aim of this study was to determine levels of hazardous trace elements (HTEs) in bottom estuarine sediments, fish and mussels collected from two sites downstream of the Raša River mouth, and a wild boar’s kidney donated by hunters. The pseudo-total concentrations of 21 HTEs in sediments were obtained by the X-ray fluorescence (XRF) technique. The results showed that sediment collected closest to the former Raša coal separation unit Štalije was enriched in V, Sr, Ni, Cu, and Pb. Concentrations of HTEs in flathead grey mullet, wild blue mussels, and wild boar were obtained by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that Pb, Cd and Hg in fish and wild mussels were not elevated compared to the Regulation levels of contaminants in food. Lead and Cd in the kidney of a wild boar exceeded the prescribed maximum values for food. This study warrants further geochemical investigations of the Raša Bay environment