Formation of gold/silver composite nanoparticles by pulsed laser ablation of gold–silver layered films in liquid

Nanoparticles of high purity can be produced from a variety of materials by pulsed laser ablation of solids in liquid. Composite nanoparticles are of great importance in various applications such as catalysis or biomedicine and the process of their formation is still a subject of intense research. In this work, gold/silver composite nanoparticles were synthesized in aqueous media by ns pulsed laser ablation of gold–silver multilayer targets with different absolute layer thicknesses and layer thickness ratios. The generated nanoparticles showed a log-normal distribution of sizes, with average diameter in the 20–40 nm range and standard deviation of 9–30 nm. By comparing the UV–VIS absorbance spectra of the nanoparticle colloids with two theoretical calculations (based on the Mie and the BEM model), it was found that there is a direct correlation between the average Au and Ag content of the nanoparticles and the composition of the films on the substrate. Assuming thermal ablation, our model calculations showed that there is a maximum thickness of the top layer up to which both layers can be ablated simultaneously and alloy nanoparticles can be produced

A comparative study of femtosecond pulsed laser ablation of meloxicam in distilled water and in air

The increasing prevalence of water insoluble or poorly soluble drugs calls for the development of new formulation methods. Common approaches include the reduction of particle size and degree of crystallinity. Pulsed laser ablation is a clean technique for producing sub-micrometre sized drug particles and has the potential to induce amorphization. We studied the effect of femtosecond pulsed laser ablation (ELI ALPS THz pump laser system: λ c = 781 nm, τ = 135 fs) on meloxicam in distilled water and in air. The ablated particles were characterized chemically, morphologically and in terms of crystallinity. We demonstrated that femtosecond laser ablation can induce partial amorphization of the particles in addition to a reduction in particle size. In the case of femtosecond pulsed laser ablation in air, the formation of pure meloxicam spheres showed that this technique can produce amorphous meloxicam without the use of excipients, which is a unique result. We also aimed to describe the ablation processes in both investigated media

Lézerek az optikában, spektroszkópiában és az anyagtudományokban = Lasers in optics, spectroscopy and material sciences

Ezen pályázat eredményei az SzTE Fizika Doktori Iskola négy tudományos részterületén (femtoszekundumos optika, lézerek anyagtudományi alkalmazása, valamint csillagászati- és fotoakusztikus spektroszkópia) dolgozó kollektíva egymással összefüggő, azt kiegészítő tudományos munkája révén jöttek létre, melyek főbb eredményei a következőek: Egy új, csak lineáris optikai eljárást fejlesztettünk ki lézerimpulzusok hordozó-burkoló fázis csúszásának mérésére, mely független a hullámhossztól és a sávszélességtől. Immerziós, két-nyalábos interferenciás lézerindukált hátsóoldali nedves maratási eljárást alkalmazva 104 nm periódusú kvarc rácsot készítettünk. A lézerrel generált fém-dielektrikum rácsok periódikus adhézió- és plazmon-mező modulációján alapuló új SPR bio-szenzorizációs eljárást dolgoztunk ki. Folyadékok ultrarövid impulzusokkal történő ablálásával kontrollált méreteloszlású és összetételű nanorészecskék előállításának új módszerét dolgozták ki. AFM fejlesztés során egy új amplitúdó és fázismérési algoritmust dolgoztunk ki, amely egyetlen rezgésből is képes az amplitúdó és fázis meghatározására. Kifejlesztettünk egy lézeres ammóniamérő műszert, amely alkalmas koncentráció és fluxus nagyérzékenységű, automatikus mérésére, terepi körülmények között. Nagyfelbontású spektroszkópiával kimutattuk, hogy két módusban rezgő csillagokban a nagyobb fémtartalmúaknál a rezgési periódusok aránya kisebb. | The results of this project have been achieved by the co-operative work of colleagues from four scientific fields of the Physics PhD Program of the University of Szeged, as femtosecond optics, laser-matter (surface) interactions, photoacoustical and astronomical spectroscopy. The major findings of these basic researches are as follows: A new linear optical method was developed for the measurement of the carrier envelope phase drift of laser pulses, which is independent of the wavelength and bandwidth. Immersion two-beam interferometric laser induced backside wet etching method was applied to prepare fused silica gratings with a 104 nm period. Novel SPR bio-sensing method was developed based on the periodic adhesion and plasmon-field enhancement on the laser-induced metal-dielectric gratings. It has been demonstrated that ultrashort pulse ablation of liquids is a novel approach to the production of nanoparticles of controlled composition and size distribution. A new amplitude and phase measurement algorithm for AFM was developed, which allows the determination of phase and amplitude from one vibration of the tip. We have developed a laser based instrument for accurate and automatic ammonia concentration and flux monitoring under field conditions. From high-resolution spectroscopy we pointed out that in double-mode pulsating stars the ones with higher metallicities have lower period ratios