Applications of Free Electron Lasers in Biology and Medicine

The advent of free electron lasers opens up new opportunities to probe the dynamics of ultrafast processes and the structure of matter with unprecedented spatial and temporal resolution. New methods inaccessible with other known types of radiation sources can be developed, resulting in a breakthrough in deep understanding the fundamentals of life as well as in numerous medical and biological applications. In the present work the properties of free electron laser radiation that make the sources excellent for probing biological matter at an arbitrary wavelength, in a wide range of intensities and pulse durations are briefly discussed. A number of biophysical and biomedical applications of the new sources, currently considered among the most promising in the field, are presented

Oxygen and Silicon K-EXAFS in SiO2\text{}_{2}

The aim of this work was to calculate EXAFS (extended X-ray absorption fine structure) profile of the constituent elements for SiO$\text{}_{2}$ in β-quartz and in its amorphous form within a single scattering curved waves approximation. This method extends the EXAFS analysis to lower energies than the plane wave approximation. We have used wave functions for free ions and Pendry's procedure for central atom phase shifts calculation. Our results for Si K-EXAFS were consistent with experiment, whereas a significant deviation from experimental results for O K-EXAFS was observed. Similar EXAFS profiles for β-quartz and amorphous SiO$\text{}_{2}$ were obtained from calculations

Extended X-ray Bremsstrahlung Isochromat Fine Structure of SiO2\text{}_{2}

X-ray bremsstrahlung isochromat of amorphous SiO$\text{}_{2}$ deposited on Si crystal was measured in an energy range up to 250 eV above the threshold. Extended X-ray bremsstrahlung isochromat he structure (EXBIFS) was observed up to 150 eV for SiO$\text{}_{2}$ studied. The Fourier transform of EXBIFS showed two peaks originated from first and second neighbors around silicon and oxygen ions. Model calculations of EXBIFS of amorphous SiO$\text{}_{2}$ were performed in terms of single scattering of spherical waves and compared with experimental results

Photoemission and Inverse Photoemission Studies of SiO2\text{}_{2}

Occupied and unoccupied electron states of amorphous silicon dioxide film supported on Si crystal are studied by using X-ray photoemission and, for the first time, X-ray inverse photoemission (X-ray bremsstrahlung isochromat method). A special care was undertaken to minimize decomposition of silicon oxide during X-ray bremsstrahlung measurements. The experimental spectra are compared with theoretical band structure calculations for amorphous SiO$\text{}_{2}$ from the literature and good overall agreement is found

Applications of Free Electron Lasers in Biology and Medicine

The advent of free electron lasers opens up new opportunities to probe the dynamics of ultrafast processes and the structure of matter with unprecedented spatial and temporal resolution. New methods inaccessible with other known types of radiation sources can be developed, resulting in a breakthrough in deep understanding the fundamentals of life as well as in numerous medical and biological applications. In the present work the properties of free electron laser radiation that make the sources excellent for probing biological matter at an arbitrary wavelength, in a wide range of intensities and pulse durations are briefly discussed. A number of biophysical and biomedical applications of the new sources, currently considered among the most promising in the field, are presented

Applications of Free Electron Lasers in Biology and Medicine

The advent of free electron lasers opens up new opportunities to probe the dynamics of ultrafast processes and the structure of matter with unprecedented spatial and temporal resolution. New methods inaccessible with other known types of radiation sources can be developed, resulting in a breakthrough in deep understanding the fundamentals of life as well as in numerous medical and biological applications. In the present work the properties of free electron laser radiation that make the sources excellent for probing biological matter at an arbitrary wavelength, in a wide range of intensities and pulse durations are briefly discussed. A number of biophysical and biomedical applications of the new sources, currently considered among the most promising in the field, are presented

BIS Study of Silicon Nitride: Experiment and Theory

X-ray bremsstraMiing isochromat spectroscopic (BIS) study of unoccupied electron states in silicon nitride was performed in an extended energy range. The sample was a 3100 Å layer of silicon nitride deposited on a silicon plate. The isochromat photon energy was 5415 eV. The measurement was performed up to about 250 eV above the BIS threshold. A pronounced maximum of the density of electron state at about lOeV and a weak extended structure up to 200eV were observed. Calculations of the BIS intensity in extended energy range have been performed for silicon nitride using a muffin-tin potential approximation, multiple scattering method and partial probabilities of BIS transitions. The main result is that the BIS of silicon nitride is produced mostly at silicon ions and the BIS extended structure forms mainly due to electron scattering by nearest neighbouring nitrogen ions

Optimization of Cathodic Arc Deposition and Pulsed Plasma Melting Techniques for Growing Smooth Superconducting Pb Photoemissive Films for SRF Injectors

Superconducting photoinjectors have a potential to be the optimal solution for moderate and high current cw operating free electron lasers. For this application, a superconducting lead (Pb) cathode has been proposed to simplify the cathode integration into a 1.3 GHz, TESLA-type, 1.6-cell long purely superconducting gun cavity. In the proposed design, a lead film several micrometres thick is deposited onto a niobium plug attached to the cavity back wall. Traditional lead deposition techniques usually produce very non-uniform emission surfaces and often result in a poor adhesion of the layer. A pulsed plasma melting procedure reducing the non-uniformity of the lead photocathodes is presented. In order to determine the parameters optimal for this procedure, heat transfer from plasma to the film was first modelled to evaluate melting front penetration range and liquid state duration. The obtained results were verified by surface inspection of witness samples. The optimal procedure was used to prepare a photocathode plug, which was then tested in an electron gun. The quantum efficiency and the value of cavity quality factor have been found to satisfy the requirements for an injector of the European-XFEL facility

Amorphous and nanocrystalline Fe85Zr7B6Cu2\mathrm{Fe_{85}Zr_7B_6Cu_2} alloys

Local atomic order around Fe and Cu atoms in Fe85Zr7B6Cu2 amorphous and crystalline alloys annealed for 1 h at temperatures 420°C, 460°C, 480°C, 500°C and 570°C were studied by X-ray absorption. It was found that, in the as-quenched alloy, both Fe and Cu atoms are in an amorphous environment. For Fe atoms we have observed a systematic increase of a body centered cubic (bcc) type of ordering with increasing temperature of anneal and bcc Fe crystallites growing at temperatures higher than 460°C. In contrast, for Cu atoms, we have observed face centered cubic (fcc) ordering in all the annealed alloys and that Cu nanocrystallites started to grow at a temperature of 420°C, while the Fe atoms remained in an amorphous matrix