An experimental station to study the interaction of intense femtosecond vacuum ultraviolet pulses generated by the TTF1 free electron laser (FEL) (DESY, Germany) with solids was developed. The vacuum chamber, the sample holder and the detectors had been designed to fulfill strong constraints caused both by the unique properties of the interacting radiation and by TTF1 FEL innovative design. The applied mounting system allowed one to move and rotate the samples precisely with 4degrees of freedom and to heat them up to the maximal temperature of 1000K. In order to accomplish the in situ growth of thin metallic layers on the sample surfaces, evaporation cells had been installed in the vacuum chamber. A time-of-flight apparatus capable of recording both electrons and ions excited on the solid surfaces by the laser pulses had been included in the chamber design. A pulse energy monitor had been placed in the laser beam outside the experimental chamber. A second energy detector had been mounted inside the chamber on a rotational arm, permitting the angular resolved reflectivity measurements. The detectors placed in the chamber enabled a real-time study both of the ionized damage products and the reflected light from the interaction place on the sample surfaces. The measurements were made with respect to the primary beam incident angle and energy. Examples of the experimental results as well as an off-line analysis are presented. The usability of constructed experimental system to study of the interaction of intense, femtosecond pulses with solid matter is demonstrated.

We have measured the directional Compton profiles of a single crystal of hexagonal zinc along the [00·1], [10·0], [11·0] and [11·1] directions using high-energy (662 keV) gamma radiation from a 137Cs isotope source. The experimental data have been compared with the corresponding theoretical Korringa-Kohn-Rostoker semi-relativistic calculations. The theory slightly overestimates the electron momentum densities at low momenta regions for all measured profiles. The directional difference profiles, both experimental and theoretical, show very small anisotropy of the electron momentum density in hexagonal zinc, at most half of that presented in the literature for cubic systems.

Photoluminescence spectroscopy and positron annihilation spectroscopy probe of alloying and annealing effects in nonpolar m -plane ZnMgO thin films Appl. Phys. Lett. 96, 151904 (2010);

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Defect characterization of as-grown Zn1−xBexSe compound semiconductors was studied by positron lifetime and photoluminescence measurements. We obtain both experimental and theoretical evidence that the bulk lifetime of free positrons decreases linearly with Be alloying. The average positron lifetime increases with the temperature, indicating that both vacancies and negative ions trap positrons. The decomposition of the lifetime spectra shows that the positron lifetime of the vacancy decreases with an increase in Be content, as predicted by theoretical calculations. The concentration of vacancies and negative ions obtained from positron measurements follows the same trend with Be alloying. A comparison of positron measurements with theoretical calculations and photoluminescence experiments in Zn vapor annealed samples indicates that the vacancy corresponds to a Be vacancy. Besides, the negative ions trapping positrons at low temperatures have been attributed to Be interstitial atoms. The intensity of the B photoluminescence band correlates with the concentration of Be vacancies and Be interstitial atoms. We thus conclude that the electron levels of those defects are involved in the optical transition that leads to the B photoluminescence band.