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Photocathode laser pulse shaping is a crucial technology for enhancing the performance of X-ray free-electron lasers by optimizing the quality of electron beams generated from photocathodes within high-gradient radio frequency guns. By precisely shaping these laser pulses, it is possible to significantly reduce the transverse emittance of produced electron bunches. The optimal pulse shape is an ellipsoidal distribution, commonly referred to as the Kapchinskij–Vladimirskij profile. A pulse-shaping scheme utilizing a commercial Yb:KGW laser operating at 514 nm with a repetition rate of 1 MHz and duration of 260 fs has been developed for generating electron bunches with high peak and average power. This study presents the experimental realization of ellipsoidal pulses via three-dimensional amplitude shaping using spatial light modulators at 514 nm, followed by conversion to UV (257 nm) suitable for Cs   2 Te photocathodes. The preservation of pulse shape and a high conversion efficiency during this process are investigated and our experiments pave the way for future emittance minimization for X-ray free-electron lasers. [ABSTRACT FROM AUTHOR]

Vitamin D, a fat-soluble steroid, has increasingly taken a central role due to its crucial role in human health. It is estimated that about 40% of worldwide population are vitamin D deficient. The fish industry produces significant quantities of waste daily, with consequent high environmental impact. The aim of this work is to place a first brick for the fish waste reuse as a source of vitamin D3 extracts to be used for nutraceutical purposes. For this purpose, an UV conversion method for transforming the 7-dehydrocholesterol, highly present in fish, in vitamin D3 has been optimized. The UV wavelength, exposure time, temperature, stirring, and UV intensity were optimized using a surface response design tool. The optimized treatment was applied to five fish species with different fat percentages and the results were very promising reaching vitamin D3 levels >10 times higher than the pre-treatment ones.

Photocathode laser pulse shaping is a crucial technology for enhancing the performance of X-ray free-electron lasers by optimizing the quality of electron beams generated from photocathodes within high-gradient radio frequency guns. By precisely shaping these laser pulses, it is possible to significantly reduce the transverse emittance of produced electron bunches. The optimal pulse shape is an ellipsoidal distribution, commonly referred to as the Kapchinskij–Vladimirskij profile. A pulse-shaping scheme utilizing a commercial Yb:KGW laser operating at 514 nm with a repetition rate of 1 MHz and duration of 260 fs has been developed for generating electron bunches with high peak and average power. This study presents the experimental realization of ellipsoidal pulses via three-dimensional amplitude shaping using spatial light modulators at 514 nm, followed by conversion to UV (257 nm) suitable for Cs 2Te photocathodes. The preservation of pulse shape and a high conversion efficiency during this process are investigated and our experiments pave the way for future emittance minimization for X-ray free-electron lasers.

A key issue of X-ray free-electron lasers is the quality of the photoelectron beams generated from a photocathode by laser pulses in the high-gradient RF gun. Controlling the shape of these laser pulses can strongly reduce the transverse emittance of the generated electron bunch. For this purpose, a laser pulseshaper at 515 nm is presented that can be used directly with alkali antimonide photocathodes for photoemission. The first results regarding generation and measurement of flattop and parabolic pulses as well as introduction of modulations for THz generation are presented and show the potential for emittance optimization with 3D ellipsoidal pulses with the proposed pulseshaper. The experiments are carried out for Cs 2 Te photocathodes, which require second harmonic generation of the shaped pulses and thus allow investigation of pulseshape preservation in nonlinear frequency conversion processes. [ABSTRACT FROM AUTHOR]

A key issue of X-ray free-electron lasers is the quality of the photoelectron beams generated from a photocathode by laser pulses in the high-gradient RF gun. Controlling the shape of these laser pulses can strongly reduce the transverse emittance of the generated electron bunch. For this purpose, a laser pulseshaper at 515 nm is presented that can be used directly with alkali antimonide photocathodes for photoemission. The first results regarding generation and measurement of flattop and parabolic pulses as well as introduction of modulations for THz generation are presented and show the potential for emittance optimization with 3D ellipsoidal pulses with the proposed pulseshaper. The experiments are carried out for Cs2Te photocathodes, which require second harmonic generation of the shaped pulses and thus allow investigation of pulseshape preservation in nonlinear frequency conversion processes.

We demonstrate a novel solution-free technique which can be used to print metal oxide patterns without masks by adopting an organic vapor jet printing (VJP) method. To avoid the high deposition temperatures required for metal oxide vaporization, metal-organic compounds are first jet-printed as metal-oxide precursors and converted into metal oxides by a photo-conversion process. As an example, we show that indium oxides can easily be prepared from jet-printed films of indium acetylacetonate upon photo-conversion; the effectiveness of which is supported by X-ray photoelectron spectroscopy (XPS) showing a reduction of the carbon portion associated with the alkyl chains of the precursors. A carrier mobility of 4.5 cm 2 /V·s and an on/off ratio of 10 5 are demonstrated in the oxide thin-film transistors based on indium oxides prepared by the proposed method, illustrating the potential usefulness of this process in electronic device fabrication. [ABSTRACT FROM AUTHOR]

The correlations between defectiveness and optical properties of Er‐doped Gd2O3 nanoparticles coupled into cubic and monoclinic crystal structures were studied employing XPS and PL spectroscopies. The main focus of this research is paid to the cubic Gd2O3 phase, which is more suitable for light‐emitting purposes. It is shown that oxygen‐related point defects are the precursors for the formation of cationic irregulars – "defective" Gd3+ ions with local energy levels in the energy band gap of Gd2O3. Energy transfer from Gd3+ intrinsic defects to Er3+ dopants provides an additional channel for UV–visible radiation conversion. These Er3+ ions have bimodal distribution due to the non‐equivalent lattice sites of "defective" Gd3+ ions. An increase of Er3+ concentration leads to the giant phonon softening effect, which opens up a new prospective way to enhance energy conversion efficiency. [ABSTRACT FROM AUTHOR]

An aqueous and carbon-free metal-oxide precursor route is used in combination with a UV irradiation-assisted low-temperature conversion method to fabricate low-voltage ZnO transistors with electron mobilities exceeding 10 cm(2) /Vs at temperatures <180 °C. Because of its low temperature requirements the method allows processing of high-performance transistors onto temperature sensitive substrates such as plastic., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)