Sökning: "laser ionization"

Visar resultat 21 - 25 av 124 avhandlingar innehållade orden laser ionization.

1. 21. Attosecond Optical and Electronic Wave Packets

   Författare :Per Johnsson; Atomfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; optik; acoustics; optics; Electromagnetism; Ionization Dynamics; Electron Wave Packet Interferometry; Electron Wave Packet Control; Pulse Characterization; High-Order Harmonics; Attosecond Pulse Trains; Atom- och molekylärfysik; Atomic and molecular physics; akustik; Elektromagnetism;

   Sammanfattning : When a low-frequency laser pulse is focused to a high intensity in a gas, the electric field of the laser may become comparable to, or even exceed, the electric field between the electrons and the nucleus in the atom. Under such conditions, through a process known as high-order harmonic generation, bursts of extreme ultraviolet radiation may be emitted, with durations in the attosecond domain (1 as = 10^{-18} s), which is the time-scale of electronic processes. LÄS MER

3. 22. Sample preconcentration in open microchannels : Combinations with MALDI and nano-ESI mass spectrometry and computer simulations

   Författare :Saara Mikkonen; Åsa Emmer; Leopold Ilag; Jenny Ottosson Takanen; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Preconcentration; open microchannel; microchip; MALDI; electrospray ionization; nanoelectrospray; mass spectrometry; computer simulation;

   Sammanfattning : In this thesis a novel concept for preconcentration of biomolecules in open microchannels is presented. The preconcentration is based on electromigration of charged analytes, and detection is performed with matrix-assisted laser desorption/ionization (MALDI) or nano-electrospray ionization (nESI) mass spectrometry (MS). LÄS MER

4. 23. Femtosecond Dynamics in Water and Biological Materials with an X-Ray Laser

   Författare :H. Olof Jönsson; Carl Caleman; Nicusor Timneanu; Olle Björneholm; David van der Spoel; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Physics with specialization in Biophysics; Fysik med inriktning mot biofysik;

   Sammanfattning : Using high intensity ultrashort pulses from X-ray free electron lasers to investigate soft matter is a recent and successful development. The last decade has seen the development of new variant of protein crystallography with femtosecond dynamics, and single particle imaging with atomic resolution is on the horizon. LÄS MER

5. 24. Label free analysis and spatial distribution of molecular lipids in brain tissue and cells using mass spectrometry imaging

   Författare :Amir Saeid Mohammadi; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Mass Spectrometry Imaging; Secondary Ion Mass Spectrometry Imaging; Matrix Assisted Laser desorption Ionization; Lipids; Brain tissue;

   Sammanfattning : Lipids are important inherent components in brain and cell membranes, which play significant biological roles in cell function. Identification and localization of specific biomolecules such as peptides and lipids within cellular membranes is currently a major challenge in metabolomics and biological studies. LÄS MER

7. 25. Engineering of thermometric biosensors and characterisation of redox enzymes for improved performance of biosensors/biofuel cells

   Författare :Maria Yakovleva; Biokemi och Strukturbiologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Flow injection analysis; thermometric calorimetric biosensor; enzyme thermistor; immobilised enzyme reactor; amperometric biosensor; enzymatic biofuel cell; bioanode; pyranose dehydrogenase; cellobiose dehydrogenase; direct electron transfer; mediated electron transfer; matrix-assisted laser desorption ionization; glycosite mapping;

   Sammanfattning : The present work is mainly focused on the development of enzyme-based bioanalytical devices, which can further be applied as analytical tools for industrial, medical and environmental applications. The first part of the work deals with the practical applications of thermometric biosensors for determination of various sugars (fructose and lactose) in a real samples. LÄS MER