Changes in the Laser-Processed Ti6Al4V Titanium Alloy Surface Observed by Using Raman Spectroscopy.

This works reports on the effects of treating the surface of Ti6Al4V titanium alloy samples with a laser with a wavelength of 1064 nm, operating in a pulsed and continuous mode. The obtained surfaces with different roughness, complexity and wettability were examined by Raman spectroscopy in order to recognize the presence of titanium oxides on the functionalized surface. The layer of titanium oxides on the surface with the identified rutile phase obtained by laser treatment in the continuous wave mode is a reason for a hydrophobic surface that appeared 50 days after the treatment process. In the case of the surface obtained by the pulsed laser process, only local points at which the Raman bands attributed to the metastable phases anatase and brookite of TiO2 can be identified. In this treatment process, complete surface hydrophilicity was observed during 29 days after the functionalization process (maximal contact angle observed during this time was 68.4 deg). For some functionalization processes of different parameters, the contact angle remained immeasurable until 119 days after the functionalization process. In summary, Raman spectroscopy identifies surface changes of Ti6Al4V after laser processing.

Microstructures Manufactured in Diamond by Use of Laser Micromachining.

Different microstructures were created on the surface of a polycrystalline diamond plate (obtained by microwave plasma-enhanced chemical vapor deposition-MW PECVD process) by use of a nanosecond pulsed DPSS (diode pumped solid state) laser with a 355 nm wavelength and a galvanometer scanning system. Different average powers (5 to 11 W), scanning speeds (50 to 400 mm/s) and scan line spacings ("hatch spacing") (5 to 20 µm) were applied. The microstructures were then examined using scanning electron microscopy, confocal microscopy and Raman spectroscopy techniques. Microstructures exhibiting excellent geometry were obtained. The precise geometries of the microstructures, exhibiting good perpendicularity, deep channels and smooth surfaces show that the laser microprocessing can be applied in manufacturing diamond microfluidic devices. Raman spectra show small differences depending on the process parameters used. In some cases, the diamond band (at 1332 cm-1) after laser modification of material is only slightly wider and shifted, but with no additional peaks, indicating that the diamond is almost not changed after laser interaction. Some parameters did show that the modification of material had occurred and additional peaks in Raman spectra (typical for low-quality chemical vapor deposition CVD diamond) appeared, indicating the growing disorder of material or manufacturing of the new carbon phase.

Orthogonal Functionalization of Nanodiamond Particles after Laser Modification and Treatment with Aromatic Amine Derivatives.

A laser system with a wavelength of 1064 nm was used to generate sp² carbon on the surfaces of nanodiamond particles (NDPs). The modified by microplasma NDPs were analysed using FT-IR and Raman spectroscopy. Raman spectra confirmed that graphitization had occurred on the surfaces of the NDPs. The extent of graphitization depended on the average power used in the laser treatment process. FT-IR analysis revealed that the presence of C=C bonds in all spectra of the laser-modified powder. The characteristic peaks for olefinic bonds were much more intense than in the case of untreated powder and grew in intensity as the average laser power increased. The olefinized nanodiamond powder was further functionalized using aromatic amines via in situ generated diazonium salts. It was also found that isokinetic mixtures of structurally diverse aromatic amines containing different functional groups (acid, amine) could be used to functionalize the surfaces of the laser-modified nanoparticles leading to an amphiphilic carbon nanomaterial. This enables one-step orthogonal functionalization and opens the possibility of selectively incorporating molecules with diverse biological activities on the surfaces of NDPs. Modified NDPs with amphiphilic properties resulting from the presence carboxyl and amine groups were used to incorporate simultaneously folic acid (FA-CONH-(CH2)5-COOH) and 5(6)-carboxyfluorescein (FL-CONH-(CH2)2-NH2) derivatives on the surface of material under biocompatible procedures.