Sökning: "hydrogen bond"

Visar resultat 21 - 25 av 222 avhandlingar innehållade orden hydrogen bond.

1. 21. Trapping Tyrosine Z : Exploring the Relay between Photochemistry and Water Oxidation in Photosystem II

   Författare :Johannes Sjöholm; Stenbjörn Styring; Fikret Mamedov; A. William Rutherford; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Photosystem II; Tyrosine Z; EPR; proton-coupled electron transfer; hydrogen bond; pH;

   Sammanfattning : Photosystem II is unique! It remains the only enzyme that can oxidize water using light as energy input. Water oxidation in photosystem II is catalyzed by the CaMn4 cluster. The electrons extracted from the CaMn4 cluster are transferred to P680+ via the tyrosine residue D1-Tyr161 (YZ). LÄS MER

3. 22. Core Level Spectroscopy of Water and Ice

   Författare :Dennis Nordlund; Anders Nilsson; Martin Wolf; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; x-ray adsorption spectroscopy; photoemission spectroscopy; x-ray photoelectron spectroscopy; platinum; x-ray emission spectroscopy; density functional theory; hydrogen-bonded; H-bond; water; ice; electronic structure; excited state dynamics; proton dynamics; water adsorption; liquid water; Physics; Fysik;

   Sammanfattning : A core level spectroscopy study of ice and water is presented in this thesis. Combining a number of experiments and spectrum calculations based on density functional theory, changes in the local valence electronic structure are shown to be sensitive to the local H-bonding configurations. LÄS MER

4. 23. Catalytic Water Production from First-Principles Calculations

   Författare :Gustav Karlberg; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; platinum; Monte Carlo; first-principles; hydroxyl; transition metals; density functional theory DFT ; Metropolis; oxygen; water; water production reaction; hydrogen;

   Sammanfattning : The main subject of this thesis is the catalytic water production reaction on metal surfaces. This reaction is of great current interest due to its importance in fuel cells, a clean and efficient way to convert chemical energy into electrical. LÄS MER

5. 24. Synchrotron radiation studies of gas phase molecules : from hydrogen to DNA sugars

   Författare :Gemma Vall-llosera; Elisabeth Rachlew; Stacey Sorensen; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; KTH thesis; synchrotron radiation; gas phase; bio molecules; Atomic and molecular physics; Atom- och molekylfysik;

   Sammanfattning : This thesis summarises experimental results on the molecular spectroscopy of gas phase molecules excited by synchrotron radiation in the VUV and soft X-ray regions. We have used three different detection techniques, photon induced fluorescence spectroscopy, photoionisation mass spectroscopy and near edge X-ray absorption fine structure spectroscopy to study molecular deuterium, hydrogen sulphide, ammonia, methanol, pyridine, pyridazine, pyrimidine, pyrazine, s-triazine, and 2-deoxy-D-ribose, the last one also known as the DNA sugar. LÄS MER

7. 25. Synthetic [FeFe] Hydrogenase Active Site Model Complexes

   Författare :Lennart Schwartz; Sascha Ott; Marcetta Y. Darensbourg; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; hydrogenase mimic; proton reduction; bioinorganic chemistry; diiron hexacarbonyl complexes; artifical photosynthesis; hydrogen; Organic chemistry; Organisk kemi;

   Sammanfattning : [FeFe]-Hydrogenases (H2ases) are metalloenzymes that can catalyze the reversible reduction of protons to molecular hydrogen as part of the metabolism of certain cyanobacteria and green algae. Due to the low availability of the enzyme, synthetic complexes that mimic the natural active site in structure, function and activity are highly sought after. LÄS MER