Sub-cycle ionization dynamics revealed by trajectory resolved, elliptically-driven high-order harmonic generation.

The sub-cycle dynamics of electrons driven by strong laser fields is central to the emerging field of attosecond science. We demonstrate how the dynamics can be probed through high-order harmonic generation, where different trajectories leading to the same harmonic order are initiated at different times, thereby probing different field strengths. We find large differences between the trajectories with respect to both their sensitivity to driving field ellipticity and resonant enhancement. To accurately describe the ellipticity dependence of the long trajectory harmonics we must include a sub-cycle change of the initial velocity distribution of the electron and its excursion time. The resonant enhancement is observed only for the long trajectory contribution of a particular harmonic when a window resonance in argon, which is off-resonant in the field-free case, is shifted into resonance due to a large dynamic Stark shift.

High-order harmonic generation using a high-repetition-rate turnkey laser.

We generate high-order harmonics at high pulse repetition rates using a turnkey laser. High-order harmonics at 400 kHz are observed when argon is used as target gas. In neon, we achieve generation of photons with energies exceeding 90 eV (∼13 nm) at 20 kHz. We measure a photon flux of up to 4.4 × 10(10) photons per second per harmonic in argon at 100 kHz. Many experiments employing high-order harmonics would benefit from higher repetition rates, and the user-friendly operation opens up for applications of coherent extreme ultra-violet pulses in new research areas.

Digital in-line holography on amplitude and phase objects prepared with electron beam lithography.

We report on the fabrication and characterization of amplitude and phase samples consisting of well defined Au or Al features formed on ultrathin silicon nitride membranes. The samples were manufactured using electron beam lithography, metallization and a lift-off technique, which allow precise lateral control and thickness of the metal features. The fabricated specimens were evaluated by conventional microscopy, atomic force microscopy and with the digital in-line holography set-up at the Lund Laser Centre. The latter uses high-order harmonic generation as a light source, and is capable of recovering both the shape and phase shifting properties of the samples. We report on the details of the sample production and on the imaging tests with the holography set-up.

[Evaluation of cadmium and lead intake from vegetables by the consumer in the province of Katowice]. / Ocena pobrania kadmu i olowiu z warzywami przez konsumentów w województwie katowickim.

The amounts of Cd and Pb consumed with vegetables were determined in four groups of households: workmen, workmen-peasants, farmers and pensioned workers and persons receiving disability allowances. The chemical analysis was done, in the first place, of vegetables with edible roots in which Pb and Cd were determined by atomic absorption spectrophotometry. The vegetables were bought in 1986-1987 by the Province Gardeners Cooperative in the Province of Katowice (mining and industrial region) and from the Province of Katowice and Warsaw. The amount of Cd or Pb found in weight unit of a given vegetable multiplied by the amount of this vegetable consumed in a week served as a measure of the amount of these metals taken by the consumer. After comparing of this amount with the acceptable dose the per cent of this dose obtained from vegetables was calculated. The study showed that the vegetables brought from other provinces than Katowice contained several times less Cd and Pb than those grown in the Province of Katowice. The lowest intake of Cd and Pb with vegetables was found in the households of workmen and the highest one in the households of farmers who consumed nearly exclusively vegetables grown on their farms. The vegetables from the Province of Katowice accounted in farmer families for 40% of the acceptable maximal weekly intake of cadmium, and the intake of lead was even above this maximal level. The differences in the weekly intake of these metals between the studied groups of households were due to differences in the amounts of consumed vegetables.(ABSTRACT TRUNCATED AT 250 WORDS)

[Changes in chemical composition of selected food products in the province of Katowice]. / Zmiany skladu chemicznego wybranych rynkowych produktów spozywczych w województwie katowickim.

The levels of Mg, Fe, Mn, Cu, Pb and Cd were determined in fresh vegetables obtained from central storerooms of the WSO in Katowice which were intended for market in that Province. Vegetable samples were taken from the stores twice in the months from September to March in the years 1986-1987. At the same time similar analyses were done of raw milk and milk for consumption from the market and from certain dairy cooperatives in the Province. Besides the above metals, in the samples dry mass, ash, protein (by Kjeldahl method), calorie values (by burning in calorimetric bomb ZKL-4) were determined. The study included these mineral components which are necessary in human physiological requirements, and those which can be toxic if consumed in excess, and also those which cumulate selectively in plants and in animal and human organisms. The mutual relationships were evaluated of these components in the analysed food products based on calculated correlation coefficients. After the chemical analysis of these products it was found that the levels of Mg, Fe, Cu, Zn, Mn and Cd and Pb varied depending on the product and site of origin of the sample. The levels of heavy metals, such as Cd and Pb, were exceeding the acceptable values in the edible parts of vegetables grown in the Province of Katowice and intended for the market in that Province. The lowest levels of toxic metals and the highest content of mineral components indispensable for physiological functions were found in the vegetables brought from the neighbouring Province of Kielce.(ABSTRACT TRUNCATED AT 250 WORDS)