J. Spousta

Central European Institute of Technology

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Tomáš Šikola

Brno University of Technology

L. Dittrichová

Brno University of Technology

Jakub Zlámal

Central European Institute of Technology

Radek Kalousek

Central European Institute of Technology

Michal Urbánek

Brno University of Technology

Alois Nebojsa

Central European Institute of Technology

Petr Dub

Brno University of Technology

Jindřich Mach

Brno University of Technology

V. Peřina

Czech Academy of Sciences, Nuclear Physics Institute

David Rafaja

TU Bergakademie Freiberg

Cooperative Institutions

Brno University of Technology

Central European Institute of Technology

Centre National de la Recherche Scientifique

Masaryk University

Institute of Physical Chemistry

Czech Academy of Sciences

Czech Academy of Sciences, Institute of Scientific Instruments

Czech Academy of Sciences, Institute of Physics

Tescan (Czechia)

Czech Technical University in Prague

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Correlative Raman Imaging and Scanning Electron Microscopy: the Role of Single Ga Islands in Surface-Enhanced Raman Spectroscopy of Graphene

arXiv (Cornell University) (2022)

Jakub Piastek Jindřich Mach Stanislav Bardy Zoltán Édes Miroslav Bartošík

Surface enhanced Raman spectroscopy (SERS) is a perspective non-destructive analytic technique enabling detection of individual nanoobjects, even single-molecules. . In the paper, we have studied the morphology of Ga islands deposited on CVD graphene by ultrahigh vacuum (UHV) evaporation and local optical response of this system by the correlative Raman Imaging and Scanning Electron Microscopy (RISE). Contrary to the previous papers, where only an integral Raman response from the whole ununiformed Ga NPs ensembles on graphene was investigated, the RISE technique has enabled us to detect graphene Raman peaks enhanced by single Ga islands and particularly to correlate the Raman signal with the shape and size of these single particles. In this way and by a support of numerical simulations, we have proved a plasmonic nature of the Raman signal enhancement related to localized surface plasmon resonances (LSPR). It has been found that this enhancement is island-size dependent and shows a maximum for medium-sized Ga islands. A reasonable agreement between the simulations of the plasmon enhancement of electric fields in the vicinity of Ga islands and the experimental intensities of corresponding Raman peaks proved the plasmonic origin of the observed effect known as the Surface Enhanced Raman Spectroscopy.

Surface-Enhanced Raman Spectroscopy

10.48550/arxiv.2201.04377

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Etude de la croissance de couches de carbone amorphe hydrogene

J. Spousta

Les travaux rapportes dans ce memoire concernent l'etude de la croissance et des proprietes de films minces de carbone amorphe hydrogene, formes par depot assiste par plasma dans une decharge de type multipolaire. Nous decrivons d'abord le systeme plasma multipolaire utilise pour la croissance des films, ainsi que l'ensemble des techniques d'analyse nous ayant donne acces a la composition (microanalyses nucleaires) et aux proprietes physiques de ces films (absorption optique et infra rouge, effet raman, ellipsometrie). Le chapitre iii est consacre aux proprietes des films de carbone amorphe hydrogene que nous avons formes. En particulier, nous nous sommes interesses a la correlation entre concentration en hydrogene et proprietes physiques. Le chapitre iv est consacre a l'effet des ions durant la croissance. L'energie de ces ions a ete le parametre privilegie, mais la nature des ions ainsi que les differentes etapes de la croissance ont fait egalement l'objet d'etude. Les resultats de ces etudes ont ete comparees aux estimations des effets des ions deduits d'un programme de simulation. Dans le chapitre v, nous avons etudie des transformations des films de carbone amorphe. Ce compose est metastable et peut etre aisement modifie par un apport d'energie. C'est le cas lors de la croissance elle meme, mais ceci peut egalement etre envisage lors de traitements posterieurs au depot. L'effet d'irradiations par un laser pulse a donc ete etudie, et compare au cas plus classique de recuits thermiques rapides.

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The influence of humidity on the kinetics of local anodic oxidation

Journal of Physics Conference Series (2007)

Miroslav Bartošík David Škoda Ondřej Tomanec Radek Kalousek Pavel Jánský

In this paper the influence of relative humidity on fabrication of nanostructures at GaAs (100) surfaces by local anodic oxidation (LAO) is reported. The attention was paid both to the dimensions of oxide nanolines prepared at different relative humidities for tip-surface voltages of 6 - 9 V and tip speeds of 10 - 200 nm/s, and to the profiles corresponding to line trenches (etched in HCl after the nanoxidation). Contrary to the expectations the height and the half-width of oxide nanolines did not increase with relative humidity in the whole interval from 35% to 90%, but for lower relative humidities (< 50%) the lines were comparable in size to those prepared at 90%. However, this was accompanied with instabilities in the oxidation process resulting most probably from enhanced size variations of the water meniscus between the tip and the surface at these low humidities.

10.1088/1742-6596/61/1/016

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Role of humidity in local anodic oxidation: A study of water condensation and electric field distribution

Physical Review B (2009)

Miroslav Bartošík David Škoda Ondřej Tomanec Radek Kalousek Pavel Jánský

This paper deals with the analysis of the influence of humidity on the process of local anodic oxidation carried out by atomic force microscope (AFM) on GaAs (100) surfaces. Recent experiments have shown that the height and half width of oxide nanolines do not increase monotonously with relative humidity, but for lower relative humidities $(<50%)$ the lines comparable in size to those prepared at 90% were obtained. However, their height and width along the lines revealed significant variations. To better understand these phenomena, the AFM force-distance spectroscopy measurements together with computer simulations of an electric-field distribution and water bridge formation between the tip and the substrate at different relative humidities were carried out. Our experiments on AFM force-distance spectroscopy have not proved an enhanced water condensation between the tip and the surface at lower humidities. However, the simulations of the electric field in the vicinity of the tip at the early stages of the oxidation process at low relative humidities showed an increase in the average intensity in the oxide layer promoting the diffusion of oxidizing species toward the substrate and, hence, the formation of oxide lines under these conditions. Finally, our simulations on water bridge variations along the tip track showed that at lower humidities there are higher relative standard deviations in the size of the water bridge while the tip is being moved along the surface. This indicates why the oxide lines showed a bigger variability in size.

Oxidizing agent

10.1103/physrevb.79.195406

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Rapid heating of zirconia nanoparticle-powder compacts by infrared radiation heat transfer

Journal of the European Ceramic Society (2016)

Radek Kalousek J. Spousta Jakub Zlámal Petr Dub Tomáš Šikola

Porosimetry

Mercury intrusion porosimetry

10.1016/j.jeurceramsoc.2016.10.004

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Dynamic switching of the spin circulation in tapered magnetic nanodisks

Nature Nanotechnology (2013)

Vojtěch Uhlíř Michal Urbánek L. Hladík J. Spousta M-Y. Im

Precession

Nanosecond

Polarity (international relations)

Circulation (fluid dynamics)

Geomagnetic reversal

10.1038/nnano.2013.66

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Citations (114)

RAILWAY MEN AHD THEIER EXPOSURE TO ELF ELM FIELDS

Acta Avionica (2005)

Eleonora Čermáková J. Spousta Jakub Štěpánek

In agreement with EU the law 480/2000 gives reference value for exposure of Professional and current population within the frequency interval of ELM fields 0 Hz - 300 GHz. The present text presents measurements of electric fields intensity and magnetic induction the railway men will be exposed to.

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Threshold limit value

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Fundamentals of Physics extended (D. Halliday, R. Resnick, J.Walker)

Miroslav Černý Petr Dub Jiřı́ Komrska Michal Lenc Bohumila Lencová

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Ion beam thin film deposition, surface and thin film analysis

Tomáš Šikola J. Spousta Jakub Zlámal