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X-ray - Based Studies of Structural Dynamics in Solids and Liquids

Nüske, Ralf LU (2011) In Lund Reports in Atomic Physics LRAP-429.
Abstract (Swedish)
Popular Abstract in Swedish

Våglängden för röntgenstrålning är mycket kortare än den för synligt ljus. I själva verket är den jämförbar med avståndet mellan atomer i fasta material, vilket är i storleksordningen en tiondels nanometer. Genom att använda ljus med så kort våglängd är det möjligt att studera materials struktur på atomär nivå. Spridning av röntgenstrålar har utvecklats till ett ovärderligt verktyg för att analysera bland annat gitterstrukturen hos kristaller, såväl som strukturen hos stora biologiska molekyler. Många av ett materials egenskaper ges av dess interna struktur.



Tidsupplöst röntgenspridning har visat sig vara en kraftfull metod för att studera ändringar i strukturen hos ett... (More)
Popular Abstract in Swedish

Våglängden för röntgenstrålning är mycket kortare än den för synligt ljus. I själva verket är den jämförbar med avståndet mellan atomer i fasta material, vilket är i storleksordningen en tiondels nanometer. Genom att använda ljus med så kort våglängd är det möjligt att studera materials struktur på atomär nivå. Spridning av röntgenstrålar har utvecklats till ett ovärderligt verktyg för att analysera bland annat gitterstrukturen hos kristaller, såväl som strukturen hos stora biologiska molekyler. Många av ett materials egenskaper ges av dess interna struktur.



Tidsupplöst röntgenspridning har visat sig vara en kraftfull metod för att studera ändringar i strukturen hos ett material på atom-nivå. En mångfald av processer kan studeras: från fasövergångar i material till vibrationer i kristallgitter och kemiska reaktionsvägar. Målet med tidsupplösta studier är att följa dessa processer i realtid.



Tidsskalan för ändringar av strukturen varierar drastiskt beroende på mekanismen. Strukturförändringer inom en enkel cell tar typiskt 100 fs. Andra viktiga strukturändringar som omfattar större grupperinger av molekyler sker på en tidsskala av pikosekunder till nanosekunder. För att starta ändringar av strukturen kan olika mekanismer användas. Laserpulser kortare än 100 fs kan produceras rutinmässigt och används för att initiera ändringar av strukturen i material. Alternativt kan korta elektriska pulser användas för att starta strukturändringar i piezoelektriska material.



I detta arbete har framför allt experimentella studier genomförts för att förbättra förståelsen av strukturförändringar i material. Vi har studerat dynamiken på pikosekundnivå kopplad till smältning och återkristallisering av en halvledare, akustisk och termisk respons hos laserexciterade fasta material, och dynamiken i strukturen hos ett piezoelektriskt material.



En kortfattad beskrivning av den teoretiska bakgrunden, de experimentella teknikerna och den nödvändiga instrumenteringen ges. Detta följs av en sammanställning av publikationerna detta arbete har resulterat i. (Less)
Abstract
The wavelength of x-ray radiation is much shorter than that of visible light. In fact, it is comparable to the distances between atoms in solids, which is on the order of one tenth of a nanometer. Using light of such a short wavelength, it is possible to study the structure of materials on the atom level. Scattering of x-rays has been developed into an invaluable tool to analyze various characteristics of matter, from the lattice structure of crystals to the structure of large biological molecules. In this way, we found that many of the properties of materials depend on their internal structure.



To learn about changes in the structure of materials on the atom-level, time resolved x-ray scattering has proven a powerful... (More)
The wavelength of x-ray radiation is much shorter than that of visible light. In fact, it is comparable to the distances between atoms in solids, which is on the order of one tenth of a nanometer. Using light of such a short wavelength, it is possible to study the structure of materials on the atom level. Scattering of x-rays has been developed into an invaluable tool to analyze various characteristics of matter, from the lattice structure of crystals to the structure of large biological molecules. In this way, we found that many of the properties of materials depend on their internal structure.



To learn about changes in the structure of materials on the atom-level, time resolved x-ray scattering has proven a powerful technique. A wide variety of processes can be studied: from phase transitions in materials to vibrations in crystal lattices and pathways of chemical reactions. The aim of time-resolved studies is to follow these processes in real time.



The timescale for changes in structure varies considerably depending on the underlying mechanism. Processes involving neighboring atoms typically take about 100\,fs. Structure changes involving large groups of atoms or molecules occure on a timescale of picoseconds to nanoseconds. Different mechanisms can be used to trigger changes in structure. Laser pulses with a duration of less than 100\,fs can be produced routinely and are used to initiate ultrafast changes in the structure. Alternatively, short electrical pulses can be used to trigger structural changes in piezo-electric materials.



In this work, the main focus has been on experimental studies in order to deepen the understanding of structural changes in matter. The picosecond dynamics involved in the melting and recrystallization of a semiconductor, acoustic and thermal response of laser-excited solids, and the dynamics in the structure of a piezo-electric material have been studied. Additionally, instrumentation required for time-resolved x-ray scattering experiments has been developed. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Dr Plech, Anton, Fachbereich Physics der Universität Konstanz, Konstanz, Germany
organization
publishing date
type
Thesis
publication status
published
subject
in
Lund Reports in Atomic Physics
volume
LRAP-429
pages
180 pages
defense location
Lecture hall B, Department of Physics, Sölvegatan 14 A, Lund University Faculty of Engineering
defense date
2011-03-25 10:15
ISSN
0281-2762
ISBN
978-91-7473-084-5
language
English
LU publication?
yes
id
a6792566-7040-4ff6-ae00-76b890ae62c1 (old id 1790654)
date added to LUP
2011-02-28 14:22:28
date last changed
2016-09-19 08:45:00
@phdthesis{a6792566-7040-4ff6-ae00-76b890ae62c1,
  abstract     = {The wavelength of x-ray radiation is much shorter than that of visible light. In fact, it is comparable to the distances between atoms in solids, which is on the order of one tenth of a nanometer. Using light of such a short wavelength, it is possible to study the structure of materials on the atom level. Scattering of x-rays has been developed into an invaluable tool to analyze various characteristics of matter, from the lattice structure of crystals to the structure of large biological molecules. In this way, we found that many of the properties of materials depend on their internal structure.<br/><br>
<br/><br>
To learn about changes in the structure of materials on the atom-level, time resolved x-ray scattering has proven a powerful technique. A wide variety of processes can be studied: from phase transitions in materials to vibrations in crystal lattices and pathways of chemical reactions. The aim of time-resolved studies is to follow these processes in real time.<br/><br>
<br/><br>
The timescale for changes in structure varies considerably depending on the underlying mechanism. Processes involving neighboring atoms typically take about 100\,fs. Structure changes involving large groups of atoms or molecules occure on a timescale of picoseconds to nanoseconds. Different mechanisms can be used to trigger changes in structure. Laser pulses with a duration of less than 100\,fs can be produced routinely and are used to initiate ultrafast changes in the structure. Alternatively, short electrical pulses can be used to trigger structural changes in piezo-electric materials.<br/><br>
<br/><br>
In this work, the main focus has been on experimental studies in order to deepen the understanding of structural changes in matter. The picosecond dynamics involved in the melting and recrystallization of a semiconductor, acoustic and thermal response of laser-excited solids, and the dynamics in the structure of a piezo-electric material have been studied. Additionally, instrumentation required for time-resolved x-ray scattering experiments has been developed.},
  author       = {Nüske, Ralf},
  isbn         = {978-91-7473-084-5},
  issn         = {0281-2762},
  language     = {eng},
  pages        = {180},
  school       = {Lund University},
  series       = {Lund Reports in Atomic Physics},
  title        = {X-ray - Based Studies of Structural Dynamics in Solids and Liquids},
  volume       = {LRAP-429},
  year         = {2011},
}