Layer deposition laser ablation

An analytical procedure has been proposed for precise uranium isotope ratio measurements in a thin uranium layer on a biological surface by LA-ICP-MS using a cooled laser ablation chamber.125 One drop of uranium isotope standard reference materials NIST, 350, NIST 930, of our isotopic laboratory standard CCLU 500 (20p.l, U concentration 200 ng 1) and of uranium with natural isotopic pattern were deposited on the leaf surface and analyzed by LA-ICP-MS at well defined laser crater diameters of 10, 15, 25 and 50 p.m. A precision for measurements of isotope ratios in the range of 2.1-1.0% for 235U/238U in selected isotope standards was observed whereby the precision and the accuracy of isotope ratios compared to the non-cooled laser ablation chamber was improved.125... 

Laser ablation was used [22] to produce SiNWs 20 nm in diameter with a polycrystalline silicon core in a thin silicon oxide sheath with 1/4-1/3 of the nominal diameter and 1/3 of the weight of the SiNW. The oxide layer (which makes the SiNWs surfaces inert) was removed by a 5% H F dip for 5 min resulting in smooth, stable, H-terminated SiNW surfaces [77]. The etched SiNWs were immersed into solutions of silver nitrate and copper sulfate of different concentrations. Silver and copper ions were reduced to metallic aggregates deposited onto the surface of SiNWs. The TEM image of the sample treated with a 10 M silver nitrate solution (Figure 10.28) shows dark, round silver particles 5-50 nm in diameter. The HF-etched SiNWs treated with 1.0 x 10 M copper sulfate show much smaller (a few nm) particles (Figure 10.29) identified by EELS as Cu particles. 

Another recent, nontraditional investigation involved the use a of pump-probe technique to study the laser-ablation of tooth enamel [80] and the influence of an optically thick water layer applied onto the tooth surface [81]. Laser ablation was performed in the presence and absence of water, and synchrotron FT-IRM used to probe the chemical composition of the enamel in the thus-formed crater. FT-IRM revealed the formation of new mineral phases deposited along the crater walls after repetitive laser pulses, while the nonapatitic phases reduced the efflciency of... 

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