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Interaction of a Nd:YAG laser, operating at wavelengths of 1064 nm (23.6 J cm 22 fluence) or 532 nm (25.9 J cm 22 fluence), and pulse duration of 40 ps, with a titanium-based medical implant Ti6Al4V alloy was studied. Surface damage thresholds were estimated to be 0.9 J cm 22 and 0.25 J cm 22 at laser wavelengths 1064 nm and 532 nm, respectively. At both laser wavelengths, the energy absorbed was mostly converted into thermal energy, forming craters, albeit about 50 times deeper at 1064 nm than at 532 nm. Periodic surface structures (PSS) were also formed with both laser wavelengths, concentric, and radial at micrometer scale (3 mm to 15 mm period), parallel at nanometer scale (800 nm period with the 1064 nm laser, 400 nm with the 532 nm laser). In the case of the 532 nm laser, the concentric structures enlarge their period with accumulating laser pulse count. These features can help roughening of the implant surface and improve bio-compatibility.

The electronic structure and properties of dipotassiummonohalides are important for understanding the unique physical and chemical behavior of M(n)X systems. In the present study, K(2) X (here X=F, Cl, Br, I) clusters were generated in the vapor over salts of the corresponding potassium halide, using a magnetic sector thermal ionization mass spectrometer. The ionization energies obtained for K(2)F, K(2)Cl, K(2)Br, and K(2)I molecules were 3.82 ± 0.1 eV, 3.68 ± 0.1 eV, 3.95 ± 0.1 eV, and 3.92 ± 0.1, respectively. These experimental values of ionization energies for K(2) X (X=F, Br, and I) are presented for the first time. The ionization energy of K(2)Cl determined by thermal ionization corresponds to previous results obtained by photoionization mass spectrometry, and it agrees with the theoretical ionization energy calculated by the ab initio method. The presently obtained results support previous theoretical predictions that the excess electron in dipotassiummonohalide clusters is delocalized over two potassium atoms, which is characteristic for F-center clusters.