UV laser ablation

GeoLas,The high resolution UV laser Ablation system. Prospect of the Company MicroLas Lasersystem GmbH, Goettingen, Germany. 

Young ED, Ash RD, Galy A, Belshaw NS (2002) Mg isotope heterogeneity in the Allende meteorite measured by UV laser ablation-MC-ICPMS and comparisons with O isotopes. Geochim Cosmochim Acta 66 683-698... 

With the advent of multiple-collector inductively coupled plasma-source mass spectrometry (MC-ICPMS) it is now possible to measure Mg/ Mg and Mg/ Mg of Mg in solution with a reproducibility of 30 to 60 ppm or better (Galy et al. 2001). What is more, ultraviolet (UV) laser ablation combined with MC-ICPMS permits in situ analysis of Mg-bearing mineral samples with reproducibility of 100 to 200 ppm (Yoimg et al. 2002a). These new analytical capabilities allow mass-dependent fractionations of the isotopes of Mg to be used as tracers in natural systems. 

Young E. D., Coutts D. W., and Kapitan D. (1998b) UV laser ablation and irm-GCMS microanalysis of and... 

Kramar N., Cosca M. A., and Hunziker J. C. (2001) Heterogeneous " °Ar distributions in naturally deformed muscovite in situ UV-laser ablation evidence for micro structurally controlled intragrain diffusion. Earth Planet. Sci. Lett. 192(3), 377-388. 

Giorgis D., Cosca M., and Li S. (2000) Distribution and significance of extraneous argon in UHP eclogite (Su-Lu terrain, China) insight from in situ " Ar/ Ar UV-laser ablation analysis. Earth Planet. Sci. Lett. 181, 605 -615. 

S. Preuss, A. Demchuk, M. Stuke, Sub-picosecond UV laser ablation of metals. Appl. Phys. A 61, 33-37, 1995. 

Another important feature of ablation, which is never discussed in the photothermal models was repeatedly emphasized by Srinivasan [92] the products of pyrolysis or ablation with a CO2 laser are very different to the products of excimer laser ablation in the UV. This suggests that different processes take place between pyrolysis (thermal decomposition) and UV laser ablation. 

If the thermally induced decomposition follows the same pathway as the UV laser-induced decomposition, then it could be possible to select the polymers for LPTs according to similar principles as for UV laser ablation. The most important design features for polymers designed for UV laser ablation are an exothermic decomposition into gaseous products well-defined primary decomposition sites in the polymer main chain and a high absorptivity at the irradiation wavelengths. In future experiments these assumptions will be tested. 

All data obtained for TP strongly suggest that photochemical reactions play an important role during UV laser ablation, but also that photothermal processes are important. This is confirmed by the presence of the thermal N2 products in the TOF curves. Photothermal processes will also always be present if the polymer decomposes exothermically during a photochemical decomposition and if the quantum yields of the photochemical reaction is not equal to one (which is most of time the case). The ablation of polymers will therefore always be a photophysical process (a mixture of photochemical and photothermal processes), where the ratio between the two mechanisms is a function of the irradiation wavelength and the polymer. In addition, photomechanical processes, such as pressure produced by trapped gaseous ablation products or shock and acoustic waves in the polymer, take place and can lead to a damage of the polymer and are most important for picosecond pulses. 

Figure 8. Oxygen three-isotope plots showing resnlts from UV laser ablation analysis of CV meteorite eomponents (a) Mineralogieally altered and unaltered portions of a CAI from the Allende meteorite. The unaltered points were used by Young and Russell (1998) to suggest that the primordial oxygen reservoir(s) for the early solar system define a line with a slope of 1.00 and an intercept of -1.0 (the Y R line), (b) CAIs and chondmles from the CV meteorites Allende, Grosnaja, and Leoville. O isotopic data for these...

Shepherd Chenery (1995) pioneered the laser ablation ICP-MS (inductively coupled plasma-mass spectrometry) method of analyzing individual fluid inclusions. An UV laser ablation microprobe is used to drill a hole into a mineral, to reach an inclusion up to 60/zm below the sample surface. For the laser ablation procedure the sample is placed in a modified thermal vacuum cell. The elevated temperature in the ablation cell raises the internal vapor pressure of the inclusion, which causes instantaneous rupture and highly efficient fluid expulsion as the beam breaches the inclusion wall. The vacuum pulls the vaporized fluid into the ICP-MS, where it is analyzed for major and minor ion concentrations. The advantages of the ICP-MS method are the small spot size of the laser (<2 m), allows analysis of small inclusions (> 10/zm) in a variety of minerals (halite, calcite, quartz, and others). A wide range of ions can be analyzed simultaneously, including low concentrations of minor ions. With multicollector ICP-MS, it will be possible to analyze strontium isotopes and other stable isotopes (5 C, S 0, S S) in fluid inclusions. Laser ablation ICP-MS is not as precise as other methods ( 30%) and the results can only be reported as ionic ratios as the volume of an inclusion cannot be determined prior to analysis. However, if the concentration... 

Kukreja, L.M., Rohlfing, A., Misra, P, HiUenkamp, E, Dreisewerd, K. (2004) Cluster formation in UV laser ablation plumes of ZnSe and ZnO studied by time-of-flight mass spectrometry. Applied Physics A, 78, 641-644. 

Aubriet, F, Muller, IF (2002) About the atypical behavior of CrCP, MoCP, and WCP during their UV laser ablation/ ionization. Journal of Physical Chemistry A, 106, 6053-6059. 

Pointurier, F., Pottin, A.C., and Hubert, A. (2011). Application of nanosecond-UV laser ablation—Inductively coupled plasma mass spectrometry for the isotopic analysis of single submicrometer size uranium particles, Ana/. Chem. 83,7841-7848. 

Nemoblastoma cell fine (SKNSH) human) PEG-silane used to prevent cell attachment. UV laser ablation generated cell-adhesive regions Khung et al. (2006)... 

For geological applications ICP-MS is extremely well suited to the determination of the lanthanide elements because of its relatively simple spectrum. When coupled with UV laser ablation, it is an extremely powerful technique for... 

Excimer lasers have been the primary tools for ablation of various polymeric materials, due to their strong absorption of UV photons. However, commercially available polymers often perform poorly in UV laser ablation, such as high ablation threshold, low ablation rate and redeposition of debris, and it becomes worse at longer UV wavelengths. An interesting development in recent years has been that of designer polymers, with properties tailored to improve ablation characteristics for specific applications [8]. New... 

Sutcliffe E, Srinivasan R. (1986) Dynamics of UV laser ablation of organic polymer satiasxs. JAppl Phys 60 3315-3322. 

Johnson, T.J., Waddell, E.A., Kramer, G.W., and Locascio, L.E. (2001) Chemical mapping of hot-embossed and UV-laser-ablated microcharmels in poly(mefliyl methacrylate) using carboxylate speciflc fluorescent probes./. Appl. Surf. Sci., 181, 149-159. 

The products of UV laser ablation range from atoms and diatoms to small polyatomic molecules and small fragments of the polymer [304, 2031, 2040, 2042, 2045, 2046, 2308]. The product of laser ablation is also wavelength dependent. From poly(methyl methacrylate) of initial molecular weight M = 10 at 193 nm, the products are oxides of carbon, methyl methacrylate monomer and low molecular weight (M = 1500) fragments of the polj er. At 248 nm, the principal product is a low molecular weight fraction (M = 2500) of the polymer. From polyimide, the products are oxides of carbon, benzene, HCN and elemental carbon. 

The ablation mechanism has, to some extent, remained unclear and more investigation is probably required. Two mechanisms have been proposed for the UV laser ablation of polymers ... 

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