Fabrication of [001]-oriented tungsten tips for high resolution scanning tunneling microscopy.

The structure of the [001]-oriented single crystalline tungsten probes sharpened in ultra-high vacuum using electron beam heating and ion sputtering has been studied using scanning and transmission electron microscopy. The electron microscopy data prove reproducible fabrication of the single-apex tips with nanoscale pyramids grained by the {011} planes at the apexes. These sharp, [001]-oriented tungsten tips have been successfully utilized in high resolution scanning tunneling microscopy imaging of HOPG(0001), SiC(001) and graphene/SiC(001) surfaces. The electron microscopy characterization performed before and after the high resolution STM experiments provides direct correlation between the tip structure and picoscale spatial resolution achieved in the experiments.

Transition metal phthalocyanines: insight into the electronic structure from soft x-ray spectroscopy.

Transition metal phthalocyanines (MPc's) are an interesting class of material, and their magnetic and electronic properties are determined by the orbital occupation of the transition metal 3d orbitals incorporated in the molecules center. Thus, the ground state configuration of the transition metal center is very important for a complete understanding of these materials. We present experimental data taken using x-ray absorption and x-ray photoemission spectroscopy together with a theoretical interpretation of MPc series with M=Zn, Cu, Ni, Co, Fe, and Mn. The combination of these methods allows us to narrow down possible dominating ground state configurations and shed a brighter light on the electronic structure of these complexes.

Spin and orbital ground state of Co in cobalt phthalocyanine.

The 3d orbital ground state of transition-metal ions that are incorporated in a molecular matrix determines the total spin of the transition-metal ion as well as the spin anisotropy and thus the essential magnetic properties of the corresponding molecule. However, there is little known to date on the exact 3d ground state of many molecular systems, including quite complex molecular magnets as well as relatively simple systems such as, for instance, cobalt phthalocyanine (CoPc). For the latter, there are contradictory theoretical predictions with respect to the occupation of the various Co 3d electronic levels. We demonstrate that polarization-dependent X-ray absorption spectroscopy in combination with a simulation of the spectra is able to shed a brighter light on the spin and orbital ground state of the transition-metal ion in CoPc. Our results reveal a temperature-dependent ground state and emphasize the importance of taking 3d correlation effects properly into account.

Electronic structure of the organic semiconductor copper phthalocyanine: experiment and theory.

The electronic structure of the organic semiconductor copper-phthalocyanine (CuPc) has been determined by a combination of conventional and resonant photoemission, near-edge x-ray absorption, as well as by the first-principles calculations. The experimentally obtained electronic valence band structure of CuPc is in very good agreement with the calculated density of states results, allowing the derivation of detailed site specific information.

Interaction of atomic hydrogen with the beta-SiC(100) 3 x 2 surface and subsurface.

We investigate clean and atomic hydrogen exposed beta-SiC(100) 3 x 2 surfaces by synchrotron radiation-based Si 2p core-level photoemission spectroscopy. The clean 3 x 2 surface reconstruction exhibits three surface and subsurface components. Upon hydrogen exposures, those surface and subsurface components are shifted to lower binding energies by large values, indicating significant charge transfer to the surface and subsurface regions, in excellent agreement with the recently discovered H-induced beta-SiC(100) 3 x 2 surface metallization. In addition, the interaction of hydrogen results in a large reactive component at Si 2p supporting an asymmetric charge transfer in the third plane below the surface, in agreement with previous experimental investigations. However, the results are inconsistent with recent ab initio theoretical "frozen" calculations predicting H atom to be in a bridge-bond position.

Competitive pathways via nonadiabatic transitions in photodissociation.

Photodissociation processes of molecules and radicals involving multiple pathways and nonadiabatic crossings are studied using the photofragment imaging technique and the core-sampling version of time-of-flight spectroscopy. Capabilities and challenges are illustrated by two systems. The isocyanic acid system demonstrates how interactions among potential energy surfaces can change during dissociation. The hydroxymethyl photodecomposition system highlights Rydberg-valence interactions common in free radicals. The cross-fertilization between theory and experiment is emphasized.

[Effect of radiation and other factors on the pathogenesis of various histologic types of lung cancer in workers of radiochemical plants]. / Vliianie radiatsionnykh i neradiatsionnykh faktorov na vozniknovenie razlichnykh gistologicheckikh tipov raka lëgkovo u rabotnikov radiokhimicheskogo predpriiatiia.

Adenocarcinoma frequency in Pu incorporation-related lung cancer patients among plutonium workers was found to be 74% versus 33% in control. Each histological pattern of lung cancer appeared to be related to several etiological factors but in varying degree. Incorporated Pu proved the strongest factor in adenocarcinoma development. Its odds ratio (OR) was 6.9, while that for smoking-4.3. However, smoking appeared to be the most significant factor in squamous cell carcinoma genesis (OR-6.8). Among other factors were chronic obstructive pathology of the lung (OR-3.9) and reduced body weight (OR-2.1). The OR for Pu incorporation was 3.9. Squamous cell carcinomas were traced to reduced body weight (OR-2.9), heavy smoking (smoking index more than 500) (OR-3.5). However, no significant relationship has been established between carcinogenesis and Pu incorporation.

[Study of the anticarcinogenic characteristics of the trace element, selenium, sanitary-hygienic experiment]. / Issledovanie antikantserogennykh svoistv mikroélementa selena v sanitarno-gigienicheskom éksperimente.

Enrichment of rat daily diets by 1-2 (up to 5) mg selenium increased nonspecific resistance of animals to ionizing radiation. Incidence of mammary, pituitary, and thyroid tumors as well as of leukemia were lower as compared with control animal group given no selenium.

[Localization of lung cancer in persons exposed to plutonium-239]. / Lokalizatsiia raka lëgkikh u rabotavshikh s plutoniem-239.

Pulmonary cancer site was studied in 131 workers engaged into radioactive chemicals production and 178 examinees of control group. All examinees died in 1965-1989. Incorporation of plutonium-239 increased the number of lower lobe pulmonary cancers (upper-0.49; medium-0.06; lower-0.45) compared to 0.72; 0.03; 0.25 in control group. Ratio of cancer sites attributing to plutonium-239 was calculated for various levels of relative risk. Cancer site in the lower lobe appeared to show high probability attributing to plutonium-239 with relative risk over 1.39; in the case of upper lobe the relative risk was 3.67.

Dynamic x-ray diffraction by a multilayer mirror modulated with a transverse acoustic wave.

Dynamic diffraction of an x-ray plane wave by a multilayer mirror modulated with a transverse acoustic wave is analyzed on the basis of rigorous multiwave mode theory. Particular attention is given to the case when λs > τ. where λs is the acoustic wavelength and τ is the extinction length. It has been derived that with increasing sound amplitude, splitting arises in every point of the kinematic branch interaction for both λs < τ and λs > τ. Accordingly the rocking curve takes the form of separate rows of peaks of Bragg diffraction into separate orders, the widths of the peaks being smaller than the width of the Bragg mirror image without modulation. The widths decrease with increasing modulation amplitude.

[Intrapleural anesthesia following thoracic surgery and in chest trauma]. / Vnutriplevral'noe obezbolivanie posle torakal'nykh operatsii i pri travme grudi.

The analgesic effect of intrapleural administration of local anesthetics (lidocaine, trimecaine, azocaine) has been studied in 180 patients after thoracic surgery and with chest trauma. The effect was assessed on the basis of subjective (visual analogue 10-score scale) and objective findings (hemodynamic parameters, spirograms, ECG). In control patients analgesia was performed by intramuscular promedol administration. It has been shown that fractionated intrapleural administration of local anesthetics is an effective and safe analgesic technique after thoracic surgery and in chest trauma.

[Morphological changes in the intrapulmonary bronchi of rats a long time after 239PuO2 inhalation]. / Morfologicheskie izmeneniia vnutrilegochnykh bronkhov u krys v otdalennom periode posle ingaliatsii 239PuO2.

Destructive, inflammatory, sclerotic, compensatory and adaptive, pretumoral and tumoral changes in the respiratory tracts of rats were revealed 180-540 days following a single inhalation of 239PuO2. The thickness of the bronchus wall and the diameter of their lumen remained significantly increased, as compared with the controls of the same age, throughout the entire period of observation.