Low energy focused x-ray beams could be used to irradiate tumors inside soft tissue within 5 cm of the surface.

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Magnetic Hyperfine and Nuclear Quadrupole Interactions (HFI and NQI) are now important tools for characterization of systems of interest in materials research and industry. Boron-Trifluoride is an inorganic compound that is very important in this respect as a catalyst in chemical physics research and industry, forming complexes in the process with compounds like ammonia, water and methyl alcohol. The present paper deals with the BF 3 -NH 3 complex and methyl derivatives BF 3 NH x (CH 3 ) 3−x for which we have studied the electronic structures, binding energies, and 19 F* (I = 5/2) nuclear quadrupole interactions using the first-principles Hartree-Fock-Roothaan procedure combined with electron correlation effects. Our

The electronic structures and nuclear quadrupole interactions (NQI) of the 19 F* (I = 5/2) state of 19 F nucleus in solid BF 3 are studied using the first-principles Hartree-Fock-Roothaan procedure including many-body electron correlation effects. The calculated NQI parameters, 19 F* quadrupole coupling constant (e 2 qQ) and asymmetry parameter η, were found to be in satisfactory agreement with experiment for the solid state system, which gives confidence in the reliability of the calculated electronic structures in the solid and hence the factors found to influence the binding of the molecules in the solid. It was found that the intermolecular binding energy primarily arises from Van der Waals (VDW) interactions between the molecules resulting from intermolecular many-body effects, which counteract the repulsive interactions between the molecules arising from one-electron Hartree-Fock (HF) theory.

Focusing x-ray optics can be used to increase the intensity onto small samples, greatly reducing the data collection time for powder diffraction. Typically, the beam convergence is restricted to avoid loss of resolution since the focused beams broaden the resulting powder diffraction rings. However, the resolution, as defined by the uncertainty in peak location, can be much less than the peak width. Two types of x-ray optics, polycapillary and doubly curved crystals, were used to focus x rays onto standard inorganic powder diffraction samples. Comparisons were made of system resolution and diffracted beam intensity using low power microfocus sources.