Bodil Holst

University of Bergen, Institute for physics and Technology, Faculty Member

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Address: University of Bergen
Department of Physics and Technology
Allegaten 55
5007 Bergen
Norway

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Margarita Gleba

University of Padova

Andrew Thomas

The University of Manchester

Prof.Dr. İbrahim USLU

Gazi University

Ilia Palaguta

Saint-Petersburg Stieglitz State Academy of Art and Design

Sammy Noumbissi

Wichita State University

Khaled Dine

University of Dr moulay taher

Franz Giessibl

University of Regensburg

Karina Grömer

Natural History Museum, Vienna, Austria

Peter Fouquet

Institut Laue-Langevin

FABIO ZAPPA

UFJF - Federal University of Juiz de Fora

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Papers by Bodil Holst

Representations of electricity: the development of a visual language for electrical phenomena

Interdisciplin Sci Rev, 2002

... phenomena. In fact, questions surrounding the issue of visualisation are particularly interes... more

The Discovery of the Electric Shock

Science, 2002

... 17. N. Zimmer, B. Holst, Interdisc. Sci. Rev. 27, 257 (2002). The Paucity of Grants Among You... more

Theoretical model of the helium zone plate microscope

by Bodil Holst and Adrià Palau

Physical Review A, 2017

Underwater Superoleophobic Sapphire (0001) Surfaces

by Bodil Holst, Naureen Akhtar, and Vårin Renate Andvik Holm

The Journal of Physical Chemistry C, 2015

Direct Images of the Virtual Source in a Supersonic Expansion �

by Bodil Holst and Gianangelo Bracco

J Phys Chem a, 2007

Direct images of the virtual source in a supersonic expansion of helium are presented. The images... more Direct images of the virtual source in a supersonic expansion of helium are presented. The images were obtained using a Fresnel zone plate with free-standing zones, 540 µm in diameter and with an outermost zone width of 50 nm. The general method can be extended to other beams, including seeded beams. Measurements were carried out at absolute source pressures ranging from 11 to 171 bar using a 10 µm nozzle with a source temperature of 320 K. The size of the virtual source was found to be strongly dependent on pressure, changing from a diameter of 67 ( 6 µm at an absolute nozzle pressure of 11 bar to 180 ( 9 µm at 171 bar. The virtual-source brightness displays a maximum at an absolute nozzle pressure of around 30 bar. This phenomenon occurs because of two competing effects: As the pressure increases, the total flux also increases, but at the same time the virtual source broadens. We modeled the expansion process by calculating the velocity distribution with solutions from the Boltzmann equation to estimate the location of the quitting surface where the frequency of interatomic collisions is assumed negligible. Realistic potentials have been used to calculate the cross section for atomic collisions and, for the velocity distribution perpendicular to the center streamline, a proper scaling with distance derived from the continuum expansion model has been introduced. A good agreement between experiments and model has been found and we discuss its approximation limits. For instance, backscattering effects are not included in the calculations and at present we cannot exclude that they also contribute to a broadening of the virtual-source size for the highest pressure regime. The results presented here are important for improving the understanding of the supersonic expansion process. The experimental method might eventually be used as a new way to test molecular and atomic interaction potentials. † Part of the "Giacinto Scoles Festschrift".

Bodil Holst

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