Interaction and what follows : Electron beam effects in dynamic systems
(2025)- Abstract
- Transmission electron microscopy (TEM) is an atomically resolved technique that allows for in depth analysis of the properties of materials by irradiating a thin sample with high energy electrons and detecting the signal imparted on, and generated by, the electron beam as it passes through. However, due to the strong interaction between electrons and matter, the sample will not remain unperturbed by the electron irradiation. There can therefore be an ambiguity about if what is observed in TEM is inherent to the material or induced by electron irradiation. One especially useful application of TEM is to observe dynamic processes by introducing external stimuli. For example, in Environmental TEM (ETEM), the sample is heated, and reactive... (More)
- Transmission electron microscopy (TEM) is an atomically resolved technique that allows for in depth analysis of the properties of materials by irradiating a thin sample with high energy electrons and detecting the signal imparted on, and generated by, the electron beam as it passes through. However, due to the strong interaction between electrons and matter, the sample will not remain unperturbed by the electron irradiation. There can therefore be an ambiguity about if what is observed in TEM is inherent to the material or induced by electron irradiation. One especially useful application of TEM is to observe dynamic processes by introducing external stimuli. For example, in Environmental TEM (ETEM), the sample is heated, and reactive gases are introduced into close proximity of the sample to allow for chemical reactions to occur. Consequently, ETEM allows for the observation of morphological, elemental, atomic, and chemical changes in a solid during solid–gas reactions, providing insight into the nature of the reaction. However, the increased complexity from the dynamic system further complicates the deconvolution of electron irradiation induced effects from the effects inherent to the reaction. Minimizing the amount of electron irradiation is one solution to limit the damage from electron irradiation. However, limiting the number of electrons interacting with the sample also limits the amount of signal that can
be collected. Consequently, methods for analyzing noisy, signal–limited data are required.
In this thesis, I discuss the ramifications of electron irradiation in TEM, both in high vacuum conditions and with reactive gases present. This is explored through carbon black oxidation (with introduced reactive gases) and the electron irradiation induced oxidation of cobalt nickel nanoparticles (without introduced reactive gases). In both of these cases there is a significant effect from the electron irradiation. For carbon black oxidation, the oxidation rate is highly dependent on the electron flux and cobalt nickel nanoparticles undergo surface oxidation during electron irradiation. These two examples illustrate the necessity of limiting the electron irradiation, and consequently, the signal. As such, I also discuss a method for analyzing noisy elemental data from TEM. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/07fa81fc-e5a8-4275-9de6-5316ecf3bcf6
- author
- Wahlqvist, David LU
- supervisor
-
- Martin Ek Rosén LU
- Maria Messing LU
- opponent
-
- Prof. Jinschek, Joerg, Technical University of Denmark (DTU), Denmark.
- organization
- publishing date
- 2025
- type
- Thesis
- publication status
- published
- subject
- keywords
- Environmental transmission electron mircoscope, Electron irradiation effects, carbon black, oxidation, cobalt nickel, model-fitting weighted least squares
- pages
- 194 pages
- publisher
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University
- defense location
- Lecture Hall KC:B, Kemicentrum, Naturvetarvägen 22, Faculty of Engineering LTH, Lund University, Lund.
- defense date
- 2025-03-05 09:00:00
- ISBN
- 978-91-8096-094-6
- 978-91-8096-095-3
- project
- Watching the death of carbon nanoparticles, atom-by-atom
- Mitigating electron beam effects through addition of hydrogen gas
- language
- English
- LU publication?
- yes
- id
- 07fa81fc-e5a8-4275-9de6-5316ecf3bcf6
- date added to LUP
- 2025-02-06 12:01:42
- date last changed
- 2025-04-04 14:16:38
@phdthesis{07fa81fc-e5a8-4275-9de6-5316ecf3bcf6,
abstract = {{Transmission electron microscopy (TEM) is an atomically resolved technique that allows for in depth analysis of the properties of materials by irradiating a thin sample with high energy electrons and detecting the signal imparted on, and generated by, the electron beam as it passes through. However, due to the strong interaction between electrons and matter, the sample will not remain unperturbed by the electron irradiation. There can therefore be an ambiguity about if what is observed in TEM is inherent to the material or induced by electron irradiation. One especially useful application of TEM is to observe dynamic processes by introducing external stimuli. For example, in Environmental TEM (ETEM), the sample is heated, and reactive gases are introduced into close proximity of the sample to allow for chemical reactions to occur. Consequently, ETEM allows for the observation of morphological, elemental, atomic, and chemical changes in a solid during solid–gas reactions, providing insight into the nature of the reaction. However, the increased complexity from the dynamic system further complicates the deconvolution of electron irradiation induced effects from the effects inherent to the reaction. Minimizing the amount of electron irradiation is one solution to limit the damage from electron irradiation. However, limiting the number of electrons interacting with the sample also limits the amount of signal that can<br/>be collected. Consequently, methods for analyzing noisy, signal–limited data are required.<br/>In this thesis, I discuss the ramifications of electron irradiation in TEM, both in high vacuum conditions and with reactive gases present. This is explored through carbon black oxidation (with introduced reactive gases) and the electron irradiation induced oxidation of cobalt nickel nanoparticles (without introduced reactive gases). In both of these cases there is a significant effect from the electron irradiation. For carbon black oxidation, the oxidation rate is highly dependent on the electron flux and cobalt nickel nanoparticles undergo surface oxidation during electron irradiation. These two examples illustrate the necessity of limiting the electron irradiation, and consequently, the signal. As such, I also discuss a method for analyzing noisy elemental data from TEM.}},
author = {{Wahlqvist, David}},
isbn = {{978-91-8096-094-6}},
keywords = {{Environmental transmission electron mircoscope; Electron irradiation effects; carbon black; oxidation; cobalt nickel; model-fitting weighted least squares}},
language = {{eng}},
publisher = {{Centre for Analysis and Synthesis, Department of Chemistry, Lund University}},
school = {{Lund University}},
title = {{Interaction and what follows : Electron beam effects in dynamic systems}},
url = {{https://lup.lub.lu.se/search/files/207860530/e-spik_ex_David.pdf}},
year = {{2025}},
}