Tag: diamond surfaces

Mar 06 2024

First-principles investigation of hydrogen-related reactions on (100)–(2×1)∶H diamond surfaces

Authors: Emerick Y. Guillaum, Danny E. P. Vanpoucke, Rozita Rouzbahani, Luna Pratali Maffei, Matteo Pelucchi, Yoann Olivier, Luc Henrard, & Ken Haenen
Journal: Carbon 222, 118949 (2024)
doi: 10.1016/j.carbon.2024.118949
IF(2022): 10.9
export: bibtex
pdf: <Carbon>

 

Graphical Abstract for Carbon publication on the adsorption of H onto diamond.
Graphical Abstract: (left) Ball-and-stick representation of aH adsorption/desorption reaction mediated through a H radical. (right) Monte Carlo estimates of the H coverage of the diamond surface at different temperatures based on quantum mechanically determined reaction barriers and reaction rates.

Abstract

Hydrogen radical attacks and subsequent hydrogen migrations are considered to play an important role in the atomic-scale mechanisms of diamond chemical vapour deposition growth. We perform a comprehensive analysis of the reactions involving H-radical and vacancies on H-passivated diamond surfaces exposed to hydrogen radical-rich atmosphere. By means of first principles calculations—density functional theory and climbing image nudged elastic band method—transition states related to these mechanisms are identified and characterised. In addition, accurate reaction rates are computed using variational transition state theory. Together, these methods provide—for a broad range of temperatures and hydrogen radical concentrations—a picture of the relative likelihood of the migration or radical attack processes, along with a statistical description of the hydrogen coverage fraction of the (100) H-passivated surface, refining earlier results via a more thorough analysis of the processes at stake. Additionally, the migration of H-vacancy is shown to be anisotropic, and occurring preferentially across the dimer rows of the reconstructed surface. The approach used in this work can be generalised to other crystallographic orientations of diamond surfaces or other semiconductors.

Mar 14 2020

SBDD 25 (aka the COVID19 edition)

Last Wednesday, the 25th edition of the Hasselt Diamond workshop started. The central topic of this celebratory edition was focused on surfaces, perfectly suited to present some of my more recent diamond based work.[1][2] Just as the previous years, the program was packed with interesting talks on anything diamond. Phosphorous doped diamond seemed to be the “new thing” this year, but I could be biased, as I was speaking on phosphorous adsorption myself. Due to a cancellation, I found myself being asked on Monday afternoon to present my work as a talk 😎 , on Wednesday morning 😯 . Because I had been a bit too ambitious in my conference abstract, this talk ended up being nicely complementary to my poster.

Poster SBDD 25 conference, Hasselt 2020

Unfortunately, this celebratory edition also fell victim to the COVID-19 crisis. In addition to being the most popular conversation topic—a close second to diamond research—, it also had a very real impact on the conference itself. The COVID-19 crisis resulted in a drop of attendance from 238 people in 2019 to 143 this year.  In addition, the quickly changing situation worldwide lead to last minute cancellations due to travel restrictions. On Thursday evening, the conference site went into lock down. Furthermore, that evening, the Belgian federal government also decided that schools and higher education should be closed, as well as pubs and restaurants, until April 3rd. There was also the urgent request for people to work from home as much as possible. (Consider this a good example of acting NOW aimed at saving people.)

Consider this computational scientist in lock down in his home lab until further notice.

Feb 18 2020

Influence of diamond crystal orientation on the interaction with biological matter

Authors: Viraj Damle, Kaiqi Wu, Oreste De Luca, Natalia Ortí-Casañ, Neda Norouzi, Aryan Morita, Joop de Vries, Hans Kaper, Inge Zuhorn, Ulrich Eisel, Danny E.P. Vanpoucke, Petra Rudolf, and Romana Schirhagl,
Journal: Carbon 162, 1-12 (2020)
doi: 10.1016/j.carbon.2020.01.115
IF(2019): 8.821
export: bibtex
pdf: <Carbon> (Open Access)

 

Graphical Abstract Carbon paper with Romana
Graphical Abstract: The preferential adsorption of biological matter on oriented diamond surfaces.

Abstract

Diamond has been a popular material for a variety of biological applications due to its favorable chemical, optical, mechanical and biocompatible properties. While the lattice orientation of crystalline material is known to alter the interaction between solids and biological materials, the effect of diamond’s crystal orientation on biological applications is completely unknown. Here, we experimentally evaluate the influence of the crystal orientation by investigating the interaction between the <100>, <110> and <111> surfaces of the single crystal diamond with biomolecules, cell culture medium, mammalian cells and bacteria. We show that the crystal orientation significantly alters these biological interactions. Most surprising is the two orders of magnitude difference in the number of bacteria adhering on <111> surface compared to <100> surface when both the surfaces were maintained under the same condition. We also observe differences in how small biomolecules attach to the surfaces. Neurons or HeLa cells on the other hand do not have clear preferences for either of the surfaces. To explain the observed differences, we theoretically estimated the surface charge for these three low index diamond surfaces and followed by the surface composition analysis using x-ray photoelectron spectroscopy (XPS). We conclude that the differences in negative surface charge, atomic composition and functional groups of the different surface orientations lead to significant variations in how the single crystal diamond surface interacts with the studied biological entities.