publications

2024

1. 

   Melting of floating ice cylinders in fresh and saline environments

   Edoardo Bellincioni, Detlef Lohse, and Sander G. Huisman

   submitted to the Journal of Fluid Mechanics, 2024

   Abs DOI Bib

   We experimentally investigated the melting of floating ice cylinders. Experiments were carried out in an aquarium, with ice cylinders with radii between 5 cm and 12 cm, floating horizontally with their axis perpendicular to gravity. The water in the aquarium was at room temperature, with salinities ranging from 0 g/L to 35 g/L. These conditions correspond to Rayleigh numbers in the range 10^5 <= Ra <= 10^9. The relative density and thus the floating behaviour could be varied by employing ice made of H2O-D2O mixtures. In addition, we explored a two-layer stable stratification. We studied the morphological evolution of the cross section of the cylinders, and explained it through the interaction with the convective flow. The cylinders only capsize in fresh water but not when the ambient is saline. This behaviour can be explained using geometrical arguments. We modelled the oscillatory motion of the cylinders after a capsize as a damped non-linear oscillator. The downward plume of the ice cylinders follows the expected scalings for a line-source plume. The plume’s Reynolds number scales with Rayleigh number in two regimes, namely Re scales as Ra^1/2 for Ra < O(10^7) and Re scales as Ra^1/3 for Ra > O(10^7), and the heat transfer (nondimensional as Nusselt number) scales as Nu scales as Ra^1/3. These scaling relations hold irrespectively of the initial size or the water salinity. Our results can qualitatively be connected to natural phenomena occurring in fjords and around isolated icebergs.

   @article{floating_cylinder,
     author = {Bellincioni, Edoardo and Lohse, Detlef and Huisman, Sander G.},
     title = {Melting of floating ice cylinders in fresh and saline environments},
     journal = {submitted to the Journal of Fluid Mechanics},
     year = {2024},
     doi = {https://doi.org/10.48550/arXiv.2411.09620},
   }

2021

1. 

   Inserting Hydrogen into Germanium Quantum Dots

   Elisa Vitiello, Courtney H. Schreiber, Emma X. Riccardi, and 8 more authors

   The Journal of Physical Chemistry C, 2021

   Abs DOI Bib

   Germanium quantum dots are very interesting for applications such as solar cells, photodetectors, and light emitters because their small bandgap can be tuned over a wide energy range by changing the particle size. One obstacle to applications is the presence of defects, both in the interior and at the surface of the nanoparticles. The defects function as nonradiative recombination centers or trap charge carriers, which will hinder further optical performance. Introducing hydrogen, as employed in a-Si:H solar cells, has proven to be a good method to counter such detrimental defect effects. In this work, germanium quantum dots were fabricated by an ultraclean, vacuum-based nanoparticle reactor in which hydrogen was supplied during growth. Optical spectroscopy of the a-Ge:H quantum dots, together with Raman and X-ray photoelectron spectroscopy, revealed a direct bandgap and that the presence of hydrogen resulted in amorphous Ge:H quantum dots. These a-Ge:H quantum dots are a step forward toward reducing charge carrier recombination in quantum dot solar cells.

   @article{doi:10.1021/acs.jpcc.1c07019,
     author = {Vitiello, Elisa and Schreiber, Courtney H. and Riccardi, Emma X. and Nedell, Jack G. and Bellincioni, Edoardo and Parravicini, Jacopo and Binetti, Simona O. and Podestà, Alessandro and Lenardi, Cristina and Pezzoli, Fabio and Di Vece, Marcel},
     title = {Inserting Hydrogen into Germanium Quantum Dots},
     journal = {The Journal of Physical Chemistry C},
     volume = {125},
     number = {44},
     pages = {24640-24647},
     year = {2021},
     doi = {10.1021/acs.jpcc.1c07019},
     url = { https://doi.org/10.1021/acs.jpcc.1c07019},
     eprint = {https://doi.org/10.1021/acs.jpcc.1c07019},
   }