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Dr in┐. Mariusz Wo╝niak

Personal Data

Position:
Phone:
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Assistant Professor
(+48) 22 116 32 77
mariusz.wozniak@ifpan.edu.pl
Mariusz Wo╝niak

Research Interests
  • Optical characterization of nanoparticles and aggregs of nanoparticles
  • Electromagnetic models and light scattering techniques
  • Complex particles description and modeling
Projects
Aggregates

Recent publications
  1. J. Archer, M. Kolwas, G. Derkachov, M. Wo╝niak, D. Jakubczyk, K. Kolwas, Optical diagnostics of surfaces of single evaporating liquid microdroplet of solutions and suspensions, Proc. SPIE 9884, Nanophotonics VI, 988427 (April 19, 2016); DOI:10.1117/12.2225786 
  2. M. Wo╝niak, G. Derkachov, K. Kolwas, J. Archer, T. T. Wojciechowski, D. Jakubczyk and M. Kolwas, Formation of Highly Ordered Spherical Aggregates from Drying Microdroplets of Colloidal Suspension, Langmuir, (2015), DOI: 10.1021/acs.langmuir.5b01621,
  3. G. Derkachov, D. Jakubczyk, M. Wo╝niak, J. Archer, M. Kolwas, High-Precision Temperature Determination of Evaporating Light-Absorbing and Non-Light-Absorbing Droplets, J. Chem. Chem. B, 118, 12566−12574, (2014).
  4. R. Ho│yst, M. Litniewski, D. Jakubczyk, M. Zientara, M. Wo╝niak, Nanoscale transport of energy and mass flux during evaporation of liquid droplets into inert gas: computer simulations and experiments, Soft Matter, 9, 7766 (2013).
Ph.D. Thesis

Wozniak M., Characterization of nanoparticle aggregates with light scattering techniques, Ph.D. thesis (in English); Marseille (France): Aix-Marseille University, 2012, WozniakM_PhD_2012.pdf.

This Ph.D. work provides and evaluates various solutions to characterize, with electromagnetic (optical) methods nanoparticles and aggregates of nanoparticles found in suspensions, aerosols and dusty plasmas...

Particles modelling
  • DLA/DLCA fractal-like aggregates
The fully adjustable (tunable) DLA-type code was developed. It allows to generate aggregates with precisely defined morphological parameters, strict self-similarity and scale-invariant properties [1].
DLCA code is under construction...
  • Buckyball-like aggregates
To model very dense and highly opaque aggregates observed in aerosols we developed a "Buckyball-like" model [2].

Fractal-like aggregate
Numerically generated fractal-like aggregate

  1. Wo╝niak M., Onofri F., Barbosa S., Yon J., Mroczka J., Comparison of methods to derive morphological parameters of multi-fractal samples of particle aggregates from TEM images, Journal of Aerosol Science, vol. 47, pp. 12-26, 2012.
  2. Onofri F. R.A., Barbosa S., Toure O., Woniak M., Grisolia C., Sizing buckyballs-like aggregates of colloidal nanoparticles by light extinction spectroscopy, Journal of Quantitative Spectroscopy and Radiative Transfer, 2012, DOI 10.1016/j.jqsrt.2012.08.018


Light Extinction Spectroscopy (LES)

LES technique measures beam transmission of particles illuminated by a polychromatic beam [1]. The beam transmission depends on particles size distribution, concentration and intrinsic properties.
This leads to an ill-posed problem which requires to inverse a Fredholm integral equation of the first kind. It was solved with the least-square algorithm with a non-negative constraint.
The experimental validation for nano silica beads, tungsten aggregates [2] and dusty plasma [1,3] proves potential of the LES technique.
SEM image
SEM image of buckyball-like aggregates of nano silica beads

  1. Onofri F., Woniak M., Barbosa S., On the optical characterization of nanoparticle and their aggregates in plasma systems, Contributions to Plasma Physics, vol. 51, pp. 1-9, 2011.
  2. Onofri F. R.A., Barbosa S., Toure O., Wo╝niak M., Grisolia C., Sizing buckyballs-like aggregates of colloidal nanoparticles by light extinction spectroscopy, Journal of Quantitative Spectroscopy and Radiative Transfer, 2012, DOI 10.1016/j.jqsrt.2012.08.018.
  3. Onofri F., Barbosa S., Woniak M., Mroczka J., Vrel D., Grisolia C., In-situ characterization of dust mobilized by laser cleaning methods and loss of vacuum accident, Fusion Science and Technology, vol. 61 (1), pp. 39-45, 2012.


TEM analysis of fractal-like aggregates

As a reference for scattering techniques [1] methods for the TEM-based analyses were developed [2].
A newly developed Modified Box-Counting Method (MBC) was found to provide less noisy estimation for the evolution of the fractal dimension with the size of aggregates than widely used 
multi-scale analysis. With the MBC method the mean fractal dimension of the experimental soot sample is lower (1.66±0.02) than the one derived with the classical multi-scale analysis (1.88±0.02).
TEM image
TEM images of soot (left) and dusty
plasma (right) aggregates


  1. Mroczka J., Woniak M., Onofri F.R.A., Algorithms and methods for the analysis of the optical structure factor of fractal aggregates, Metrology and Measurement Systems, vol. 19 (3), pp. 459-470, 2012.
  2. Woniak M., Onofri F., Barbosa S., Yon J., Mroczka J., Comparison of methods to derive morphological parameters of multi-fractal samples of particle aggregates from TEM images, Journal of Aerosol Science, vol. 47, pp. 12-26, 2012.

International cooperation

IUSTI UMR CNRS n░7343, Aix-Marseille University, Marseille, France,
Fabrice Onofri, Ph.D. D.Sc, Director of Research at CNRS, personal website.


 
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