| 1. |
- Hau-Riege, S. P., et al.
(författare)
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Wavelength dependence of the damage threshold of inorganic materials under extreme-ultraviolet free-electron-laser irradiation
- 2009
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 95:11, s. 111104-111104-3
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Tidskriftsartikel (refereegranskat)abstract
- We exposed bulk SiC and films of SiC and B4C to single 25 fs long free-electron-laser pulses with wavelengths between 13.5 and 32 nm. The materials are candidates for x-ray free-electron laser optics. We found that the threshold for surface-damage of the bulk SiC samples exceeds the fluence required for thermal melting at all wavelengths. The damage threshold of the film sample shows a strong wavelength dependence. For wavelengths of 13.5 and 21.7 nm, the damage threshold is equal to or exceeds the melting threshold, whereas at 32 nm the damage threshold falls below the melting threshold.
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| 2. |
- Chalupsky, J., et al.
(författare)
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Characteristics of focused soft X-ray free-electron laser beam determined by ablation of organic molecular solids
- 2007
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Ingår i: Optics Express. - 1094-4087. ; 15:10, s. 6036-6043
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Tidskriftsartikel (refereegranskat)abstract
- A linear accelerator based source of coherent radiation, FLASH (Free-electron LASer in Hamburg) provides ultra-intense femtosecond radiation pulses at wavelengths from the extreme ultraviolet (XUV; lambda< 100nm) to the soft X-ray (SXR; lambda<30nm) spectral regions. 25-fs pulses of 32-nm FLASH radiation were used to determine the ablation parameters of PMMA - poly ( methyl methacrylate). Under these irradiation conditions the attenuation length and ablation threshold were found to be (56.9 +/- 7.5) nm and similar to 2 mJ center dot cm(-2), respectively. For a second wavelength of 21.7 nm, the PMMA ablation was utilized to image the transverse intensity distribution within the focused beam at mu m resolution by a method developed here.
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| 3. |
- Hau-Riege, S. P., et al.
(författare)
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Damage threshold of inorganic solids under free-electron-laser irradiation at 32.5 nm wavelength
- 2007
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 90:17, s. 173128-
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Tidskriftsartikel (refereegranskat)abstract
- Samples of B4C, amorphous C, chemical-vapor-deposition-diamond C, Si, and SiC were exposed to single 25 fs long pulses of 32.5 nm free-electron-laser radiation at fluences of up to 2.2 J/cm(2). The samples were chosen as candidate materials for x-ray free-electron-laser optics. It was found that the threshold for surface damage is on the order of the fluence required for thermal melting. For larger fluences, the crater depths correspond to temperatures on the order of the critical temperature, suggesting that the craters are formed by two-phase vaporization.
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| 4. |
- Hau-Riege, S. P., et al.
(författare)
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Force Field Benchmark of Organic Liquids : Density, Enthalpy of Vaporization, Heat Capacities, Surface Tension, Isothermal Compressibility, Volumetric Expansion Coefficient, and Dielectric Constant
- 2007
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 98:14, s. 145502-
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Tidskriftsartikel (refereegranskat)abstract
- At the recently built FLASH x-ray free-electron laser, we studied the reflectivity of Si/C multilayers with fluxes up to 3×1014W/cm2. Even though the nanostructures were ultimately completely destroyed, we found that they maintained their integrity and reflectance characteristics during the 25-fs-long pulse, with no evidence for any structural changes over lengths greater than 3Å. This experiment demonstrates that with intense ultrafast pulses, structural damage does not occur during the pulse, giving credence to the concept of diffraction imaging of single macromolecules.
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| 5. |
- Kowalski, B. J., et al.
(författare)
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Mn Contribution to the Valence Band of Ga0.98Mn0.02Sb : A Photoemission Study
- 2022
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Ingår i: Acta Physica Polonica. A. - : Institute of Physics Polish Academy of Sciences. - 0587-4246 .- 1898-794X. ; 141:3, s. 175-179
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Tidskriftsartikel (refereegranskat)abstract
- The contribution of the Mn 3d states to the valence band of Ga0.98Mn0.02Sb, an important factor determining the properties of this system, including the mechanism responsible for the magnetic characteristics, has been revealed by photoelectron spectroscopy. The resonant photoemission experiment, carried out for photon energies close to the Mn 3d -> 3p excitation, allowed us to identify the spectral feature corresponding to emission from the Mn 3d states. The scanning of the valence band along the [100] direction of the Brillouin zone, by the angle-resolved photoemission experiment, showed that these states contributed to a dispersionless structure at the binding energy of 3.6 eV (with respect to the Fermi energy). The revealed shape of the Mn 3d contribution is consistent with the supposition that the p-d exchange interaction prevails as a mechanism supporting ferromagnetism in Ga1-xMnxSb.
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