| 1. |
Kaczmarek A., Hoffman J., The best conditions for the nucleation of carbon nanoparticles in laser-induced plasma,
NANOTECHNOLOGY, ISSN: 0957-4484, DOI: 10.1088/1361-6528/ac71b4, Vol.33, No.35, pp.355602-1-11, 2022 Abstract:
Despite the existence of many more efficient methods of producing carbon nanoparticles, ablation of a carbon target by a laser pulse remains important. It enables studying the bare properties of nanoparticles, not contaminated with reagents or reaction products. The present work analyses the mechanisms of nucleation and growth of nanoparticles in carbon vapours generated during ablation of graphite with a nanosecond laser pulse. The role of both the homogeneous and the heterogeneous (ions) nucleation was investigated, defining the areas of their occurrence. It has been shown that the most favourable conditions are high pressure of the order 1 GPa and relatively low temperature of about 15 000 K. Such conditions are obtainable when ablation occurs in a liquid and the fluence of the laser pulse is low, exceeding the ablation threshold about 2.7 times only. The resulting nanoparticles are relatively homogeneous and have a diameter of approximately 2.5–5 nm. Keywords:
laser ablation in liquids, nucleation, plasma expansion, laser produced plasma Affiliations:
| Kaczmarek A. | - | IPPT PAN | | Hoffman J. | - | IPPT PAN |
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| 2. |
Radziejewska J., Kaczmarek A., Mościcki T., Hoffman J., Temporal evolution of pressure generated by a nanosecond laser pulse used for assessment of adhesive strength of the tungsten–zirconium–borides coatings,
Materials, ISSN: 1996-1944, DOI: 10.3390/ma14237111, Vol.14, No.23, pp.7111-1-13, 2021Abstract:
The article presents theoretical and experimental study of shock waves induced by a nanosecond laser pulse. Generation of surface plasma pressure by ablation of the graphite absorption layer in water medium and shock wave formation were analyzed theoretically and experimentally. The amplitude and temporal variation of the shock wave pressure was determined basing on a proposed hydrodynamic model of nanosecond laser ablation and experimentally verified with use of a polyvinylidene fluoride (PVDF) piezoelectric-film sensor. The determined pressure wave was used for examination of adhesive strength of tungsten–zirconium–boride coatings on steel substrate. The magnetron sputtered (MS) W–Zr–B coatings show good adhesion to the steel substrate. The obtained experimental results prove the correctness of the proposed model as well as the suitability of the procedure for assessment of adhesive strength. Keywords:
laser pulse, shock wave, MS coatings, ternary borides, laser adhesion test Affiliations:
| Radziejewska J. | - | IPPT PAN | | Kaczmarek A. | - | IPPT PAN | | Mościcki T. | - | IPPT PAN | | Hoffman J. | - | IPPT PAN |
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| 3. |
Kaczmarek A., Denis P., Krajewski M., Mościcki T., Małolepszy A.♦, Hoffman J., Improved laser ablation method for the production of luminescent carbon particles in liquids,
Materials, ISSN: 1996-1944, DOI: 10.3390/ma14092365, Vol.14, No.9, pp.2365-1-17, 2021Abstract:
An improved method for the production of luminescent carbon nanoparticles is proposed in this work. The new method overcomes the disadvantages of commonly used approaches. It involves two-stage laser ablation in water and in aqueous solutions, where the first stage is the laser ablation of a graphite target and the second is the shredding of particles produced in the first step. The two-stage method offers the optimization of the laser pulse fluence for the performance of each process. It was found that the two-stage process of laser ablation allows producing photoluminescent carbon structures in pure water. The additional reagent may be added either in the first or second stage. The first stage performed in pure water allows avoiding the contamination of the target. Moreover, it simplifies the identification of the origin of photoluminescence. Two synthesis routes for the preparation of carbon nanoparticles by the proposed method using pure water as well as urea aqueous solution are investigated. It was found that the use of urea as a reagent results in luminescence properties similar to those obtained with other more hazardous amine-based reagents. The influence of the synthesis approach and process parameters on the structural and luminescent properties of nanoparticles is also explored in this work. Keywords:
pulsed laser ablation in liquid, carbon nanoparticles, photoluminescent particles Affiliations:
| Kaczmarek A. | - | IPPT PAN | | Denis P. | - | IPPT PAN | | Krajewski M. | - | IPPT PAN | | Mościcki T. | - | IPPT PAN | | Małolepszy A. | - | Warsaw University of Technology (PL) | | Hoffman J. | - | IPPT PAN |
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| 4. |
Kaczmarek A., Hoffman J., Morgiel J.♦, Mościcki T., Stobiński L.♦, Szymański Z., Małolepszy A.♦, Luminescent carbon dots synthesized by the laser ablation of graphite in polyethylenimine and ethylenediamine,
Materials, ISSN: 1996-1944, DOI: 10.3390/ma14040729, Vol.14, No.4, pp.729-1-13, 2021Abstract:
Fluorescent carbon dots (CDs) synthesized by pulsed laser ablation in liquid (PLAL) are still interesting materials due to their possible applications. However, unlike CDs produced by the hydrothermal method, CDs produced the synthesis products by the PLAL method were never separated by dialysis, which differentiates the synthesis products and allows the identification of the main source of fluorescence. In this work, the synthesis of fluorescent carbon dots (CDs) was performed by nanosecond laser ablation of a graphite target immersed in polyethyleneimine (PEI) and ethylenediamine (EDA), and the synthesis products were separated by dialysis. The results of optical measurements showed that the main source of luminescence of the obtained nanostructures are fluorescent particles or quasi-molecular fluorophores created in the ablation process. In the case of ablation in PEI, most of the produced molecular fluorophores are associated with carbogenic nanostructures, while in the case of EDA, free fluorescent molecules dominate. Keywords:
carbon dots, photoluminescence, laser ablation Affiliations:
| Kaczmarek A. | - | IPPT PAN | | Hoffman J. | - | IPPT PAN | | Morgiel J. | - | Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL) | | Mościcki T. | - | IPPT PAN | | Stobiński L. | - | Warsaw University of Technology (PL) | | Szymański Z. | - | IPPT PAN | | Małolepszy A. | - | Warsaw University of Technology (PL) |
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