Bose-Einstein condensation of α clusters in light and medium-heavy nuclei is studied in the frame of the field theoretical superfluid cluster model. The order parameter of the phase transition from the Wigner phase to the Nambu-Goldstone phase is a superfluid amplitude, square of the moduli of which is the superfluid density distribution. The zero mode operators due to the spontaneous symmetry breaking of the global phase in the finite number of α clusters are rigorously treated. The theory is systematically applied to N α nuclei from 12 C-52 Fe at various condensation rates. In 12 C it is found that the energy levels of the gas-like well-developed α cluster states above the Hoyle state are reproduced well in agreement with experiment for realistic condensation rates of α clusters. The electric E2 and E0 transitions are calculated and found to be sensitive to the condensation rates. The profound raison d'être of the α cluster gas-like states above the Hoyle state, whose structure has been interpreted geometrically in the nuclear models without the order parameter such as the cluster models or ab initio calculations, is revealed. It is found that in addition to the Bogoliubov-de Gennes vibrational mode states collective states of the zero mode operators appear systematically at low excitation energies from the N α threshold energy. These collective states, new-type soft modes in nuclei due to the Bose-Einstein condensation of the α clusters, emerge systematically in light and medium-heavy mass regions and are also located at high excitation energies from the ground state in contrast to the traditional concept of soft mode in the low excitation energy region.

The real-time scanning tunneling microscopy (STM) observation of Au þ ion irradiation effects on a high-temperature Si surface has been performed using our original ion gun and STM combined system. Sequential STM images of a Si(111)-7Â7 surface kept at 500 C have been obtained before, during, and after Au þ ion irradiation with 3 keV. Vacancy islands, which are two-dimensional clusters of surface vacancies, and 5Â2-Au structures were formed on the sample surface, and their size were changed during the heat treatment after the ion irradiation. This method enables us to count exact numbers of vacancies and Au atoms on the surface by measuring the sizes of vacancy islands and 5Â2-Au reconstructions. The timescale of the growth of the 5Â2-Au domain suggests that the implanted Au atoms diffuse to the surface almost without interacting with point defects induced by the ion irradiation.

An ion beam alignment system has been developed in order to realize real-time scanning tunneling microscope (STM) observation of "dopant-ion" irradiation that has been difficult due to the low emission intensity of the liquid-metal-ion-source (LMIS) containing dopant atoms. The alignment system is installed in our original ion gun and STM combined system (IG/STM) which is used for in situ STM observation during ion irradiation. By using an absorbed electron image unit and a dummy sample, ion beam alignment operation is drastically simplified and accurized. We demonstrate that sequential STM images during phosphorus-ion irradiation are successfully obtained for sample surfaces of Si(111)-7x7 at room temperature and a high temperature of 500 degrees C. The LMIS-IG/STM equipped with the developed ion beam alignment system would be a powerful tool for microscopic investigation of the dynamic processes of ion irradiation.

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We report the reactions of an iminophosphonamido-silylene (1) with different palladium complexes. The reaction of 1 with [Pd(PPh3)4] furnished a homoleptic tris(silylene)-palladium(0) complex. In contrast, treatment of 1 with [PdMe2(tmeda)]...