Sample records for laser ablation spectroscopy

  1. Double pulse laser ablation and plasma: Laser induced breakdown spectroscopy signal enhancement

    Microsoft Academic Search

    V. I. Babushok; F DELUCIAJR; J. L. Gottfried; C. A. Munson; A. W. Miziolek

    2006-01-01

    A review of recent results of the studies of double laser pulse plasma and ablation for laser induced breakdown spectroscopy applications is presented. The double pulse laser induced breakdown spectroscopy configuration was suggested with the aim of overcoming the sensitivity shortcomings of the conventional single pulse laser induced breakdown spectroscopy technique. Several configurations have been suggested for the realization of

  2. Laser ablation mass spectroscopy of nineteenth century daguerreotypes

    SciTech Connect

    Hogan, Danel L. [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States)] [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States); Golovlev, Valerie V. [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States)] [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States); Gresalfi, Michael J. [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States)] [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States); Chaney, John A. [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States)] [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States); Feigerle, Charles S. [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States)] [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States); Miller, John C. [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States)] [Life Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6125 (United States); Romer, Grant [International Museum of Photography and Film, George Eastman House, 900 East Ave., Rochester, New York 14607-2298 (United States)] [International Museum of Photography and Film, George Eastman House, 900 East Ave., Rochester, New York 14607-2298 (United States); Messier, Paul [Boston Art Conservation, 60 Oak Square Ave., Boston, Massachusetts 02135 (United States)] [Boston Art Conservation, 60 Oak Square Ave., Boston, Massachusetts 02135 (United States)

    1999-10-01

    Laser desorption mass spectroscopy has been used to characterize both modern and {approx}150-year-old daguerreotypes. Such investigations are a necessary prelude to attempts to clean them of tarnish and other contaminants by laser ablation of the surface layers. Both positive- and negative-ion time-of-flight spectra were obtained following YAG laser ablation/desorption at 1064, 532, and 355 nm. Major peaks obtained from several daguerreotypes reveal expected elements from the substrate (Ag, Cu) as well as the developing (Hg) and gilding (Au) processes. Silver clusters (Ag{sub n}) may reflect surface desorption of molecules or, alternatively, aggregates formed in the ejection process. Silver sulfide molecules observed from old daguerreotypes are the signature of the tarnishing process. (c) 2000 Society for Applied Spectroscopy.

  3. Laser Ablation Solid Sampling processes investigated usinginductively coupled plasma - atomic emission spectroscopy (ICP-AES)

    SciTech Connect

    Mao, X.L.; Ciocan, A.C.; Borisov, O.V.; Russo, R.E.

    1997-07-01

    The symbiotic relationship between laser ablation mechanismsand analytical performance using inductively coupled plasma-atomicemission spectroscopy are addressed in this work. For both cases, it isimportant to ensure that the ICP conditions (temperature and electronnumber density) are not effected by the ablated mass. By ensuring thatthe ICP conditions are constant, changes in spectral emission intensitywill be directly related to changes in laser ablation behavior. Mg ionicline to atomic line ratios and excitation temperature were measured tomonitor the ICP conditions during laser-ablation sample introduction. Thequantity of ablated mass depends on the laser pulse duration andwavelength. The quantity of mass removed per unit energy is larger whenablating with shorter laser wavelengths and pulses. Preferential ablationof constituents from a multicomponent sample was found to depend on thelaser beam properties (wavelength and pulse duration). Fornanosecond-pulsed lasers, thermal vaporization dominates the ablationprocess. For picosecond-pulsed lasers, a non-thermal mechanism appears todominate the ablation process. This work will describe the mass ablationbehavior during nanosecond and picosecond laser sampling into the ICP.The behavior of the ICP under mass loading conditions is firstestablished, followed by studies of the ablation behavior at variouspower densities. A thermal vaporization model is used to explainnanosecond ablation, and a possible non-thermal mechanism is proposed toexplain preferential ablation of Zn and Cu from brass samples duringpicosecond ablation.

  4. Laser ablation processes investigated using inductively coupled plasma–atomic emission spectroscopy (ICP–AES)

    Microsoft Academic Search

    X. L Mao; A. C Ciocan; O. V Borisov; R. E Russo

    1998-01-01

    The symbiotic relationship between laser ablation mechanisms and analytical performance using inductively coupled plasma–atomic emission spectroscopy are addressed in this work. For both cases, it is important to ensure that the ICP conditions (temperature and electron number density) are not effected by the ablated mass. By ensuring that the ICP conditions are constant, changes in spectral emission intensity will be

  5. Two-tracer spectroscopy diagnostics of temperature profile in the conduction layer of a laser-ablated plastic foil

    SciTech Connect

    Zhang Jiyan; Yang Guohong; Hu Xin; Yang Jiamin; Ding Yaonan; Ding Yongkun; Zhang Baohan; Zheng Zhijian [Research Center of Laser Fusion, P. O. Box 919-986, Mianyang 621900 (China); Xu Yan; Yan Jun; Pei Wenbin [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

    2010-11-15

    A technique that combines the diagnostics of electron temperature history and the measurements of ablation velocity with two-tracer x-ray spectroscopy has been developed for diagnosing the temperature profiles in the thermal conduction layers of laser-ablated plastic foils. The electron temperature in the plastic ablator was diagnosed using the isoelectronic line ratios of Al Ly{alpha} line to Mg Ly{alpha} line, emitted from a tracer layer of Al/Mg mixture buried under the ablator. The ablation velocity was inferred from the time delay between the onset time of x-ray line emissions from Al and Mg tracer layers buried at two depths in the ablator, respectively. From the measured electron temperatures and ablation velocity, the electron temperature profile in the conduction layer was inferred. The measured temperature profile was compared with the simulated one and reasonable agreement was found.

  6. Progress of laser ablation for accelerator mass spectroscopy at ATLAS utilizing an ECRIS.

    PubMed

    Scott, R; Palchan, T; Pardo, R; Vondrasek, R; Kondev, F; Nusair, O; Peters, C; Paul, M; Bauder, W; Collon, P

    2014-02-01

    Beams of ions from the laser ablation method of solid materials into an electron cyclotron resonance ion source (ECRIS) plasma have been used for the first time in experiments at ATLAS. Initial accelerator mass spectroscopy experiments using laser ablation for actinides and samarium have been performed. Initial results of coupling the laser system to the ECR source have guided us in making a number of changes to the original design. The point of laser impact has been moved off axis from the center of the ECR injection side. Motor control of the laser positioning mirror has been replaced with a faster and more reliable piezo-electric system, and different raster scan patterns have been tested. The use of the laser system in conjunction with a multi-sample changer has been implemented. Two major problems that are being confronted at this time are beam stability and total beam intensity. The status of the development will be presented and ideas for further improvements will be discussed. PMID:24593480

  7. ablation laser spectrometer

    E-print Network

    ablation laser mass spectrometer molecular beam REMPI laser NREL has designed and developed a combined laser ablation/ pulsed sample introduction/mass spectrometry platform that integrates pyrolysis and/or laser ablation with resonance- enhanced multiphoton ionization (REMPI) time-of-flight mass

  8. Laser ablation: LIBS and ICPMS

    SciTech Connect

    Russo, Richard E.; Gonzalez, Jhanis; Liu, Chunyi

    2006-08-29

    Laser ablation has become a dominant technology for directsolid sampling chemical analysis. Commonly used detection modalitiesinclude LIBS (laser induced breakdown spectroscopy) for directspectroscopic analysis from the laser-induced plasma at the samplesurface,and ICPMS (inductively coupled plasma mass spectroscopy) in whichthe ablated aerosol is transported and excited in a secondary source.Each measurement approach dictates the laser parameters required foroptimum performance. Fundamental and experimental research studies haveled to significant improvements in performance metrics for laser ablationsolid sampling chemical analysis using both LIBS and ICPMS.

  9. Laser ablation mass removal versus incident power density during solid sampling for inductively coupled plasma atomic emission spectroscopy

    SciTech Connect

    Shannon, M.A.; Mao, X.L.; Fernandez, A.; Chan, W.T.; Russo, R.E. [Lawrence Berkeley National Lab., CA (United States)

    1995-12-15

    For laser ablation solid sampling, the quantity of material ablated (removed) influences the sensitivity of chemical analysis. The mass removal rate depends strongly on the laser power density, which is the main controllable parameter for a given material and wavelength parameter using laser solid sampling for inductively coupled plasma atomic emission spectroscopy (ICP-AES). For a wide variety of materials, a decrease in the rate of change, or roll-off, in mass removed is observed with increasing incident laser power density. The roll-off results from a change in the efficiency of material removed by the laser beam, primarily due to shielding of the target from the incident laser energy by a laser-vapor plume interaction. Several analytical technologies were employed to study the quantity of mass removed versus laser power density. Data for mass ablation behavior versus laser power density are reported using ICP-AES, atomic emission from a laser-induced plasma near the sample surface, acoustic stress power in the target, and measurements of crater volumes. This research demonstrates that the change in ICP-AES intensity with laser power density is due to changes in the mass removal. The roll-off in mass ablation is not due to a change in particle size distribution of the ablated species, fractionation of the sample, or a change in transport efficiency to the ICP torch. 29 refs., 10 figs.

  10. Time-Resolved FTIR and Mass Spectroscopy of Laser-Ablated Magnesium.

    NASA Astrophysics Data System (ADS)

    Miyamoto, Y.; Ikeda, N.; Tang, J.; Kawaguchi, K.; Masaki, C.

    2012-06-01

    Laser-ablated Magnesium (Mg) was subjected to time-resolved Fourier transform emission spectroscopy combined with quadrupole mass spectroscopy. Emission of Mg atoms was observed in 2000 ˜4000 cm-1 region with resolution of 0.03 cm-1. It was found that emission lines consist of two components with different Doppler width. One with wider linewidth appeared just after ablation, while the other appeared after about 10 ?s. Doppler width of the narrow one corresponds to estimated velocity of atoms sputtered directly from bulk Mg. Mass spectra suggested major products of the ablation under our experimental conditions are Mg^+ and Mg2+. MgO+ was also observed in the mass spectra under thin oxygen condition (˜10-4 Torr). Considering the linewidth and energy levels of these species, the wide component is attributed to Mg atoms produced by dissociative recombination of MgO+ and electrons. Information about the electronic energy level of MgO+ was also obtained, which is compared with {ab initio} calculations.

  11. Laser-induced Breakdown Spectroscopy and ablation threshold analysis using a megahertz Yb fiber laser oscillator

    NASA Astrophysics Data System (ADS)

    Parker, Gregory J.; Parker, Daniel E.; Nie, Bai; Lozovoy, Vadim; Dantus, Marcos

    2015-05-01

    A LIBS system is demonstrated using a 100 m cavity Yb fiber oscillator producing ~ 70 ps, 320 nJ clusters of 50-100 fs sub-pulses at 2 MHz. A new empirical model for femtosecond ablation is presented to explain the LIBS signal intensity's non-linear dependence on pulse fluence by accounting for the Gaussian beam's spatial distribution. This model is compared to experimental data and found to be superior to linear threshold fits. This model is then used to measure the ablation threshold of Cu using a typical amplified Ti:sapphire system, and found to reproduce previously reported values to within ~ 20%. The ablation threshold of Cu using the Yb fiber oscillator system was measured to be five times lower than on the amplified Ti:sapphire system. This effect is attributed to the formation of nanostructures on the surface, which have previously been shown to decrease the ablation threshold. The plasma lifetime is found to be ~ 1 ns, much shorter than that of nanosecond ablation, further indicating that the decreased threshold results from surface effects rather than laser-plasma interaction. The low threshold and high pulse energy of the Yb fiber oscillator allows the acquisition of LIBS spectra at megahertz repetition rates. This system could potentially be developed into a compact, fiber-based portable LIBS device taking advantage of the benefits of ultrafast pulses and high repetition rates.

  12. Laser ablation of blepharopigmentation

    SciTech Connect

    Tanenbaum, M.; Karas, S.; McCord, C.D. Jr. (Univ. of Miami School of Medicine, FL (USA))

    1988-01-01

    This article discusses laser ablation of blepharopigmentation in four stages: first, experimentally, where pigment vaporization is readily achieved with the argon blue-green laser; second, in the rabbit animal model, where eyelid blepharopigmentation markings are ablated with the laser; third, in human subjects, where the argon blue-green laser is effective in the ablation of implanted eyelid pigment; and fourth, in a case report, where, in a patient with improper pigment placement in the eyelid, the laser is used to safely and effectively ablate the undesired pigment markings. This article describes in detail the new technique of laser ablation of blepharopigmentation. Potential complications associated with the technique are discussed.

  13. Characterization of laser ablation of copper in the irradiance regime of laser-induced breakdown spectroscopy analysis

    NASA Astrophysics Data System (ADS)

    Picard, J.; Sirven, J.-B.; Lacour, J.-L.; Musset, O.; Cardona, D.; Hubinois, J.-C.; Mauchien, P.

    2014-11-01

    The LIBS signal depends both on the ablated mass and on the plasma excitation temperature. These fundamental parameters depend in a complex manner on laser ablation and on laser-plasma coupling. As several works in the literature suggest that laser ablation processes play a predominant role compared to plasma heating phenomena in the LIBS signal variations, this paper focuses on the study of laser ablation. The objective was to determine an interaction regime enabling to maximally control the laser ablation. Nanosecond laser ablation of copper at 266 nm was characterized by scanning electron microscopy and optical profilometry analysis, in air at 1 bar and in the vacuum. The laser beam spatial profile at the sample surface was characterized in order to give realistic values of the irradiance. The effect of the number of accumulated laser shots on the crater volume was studied. Then, the ablation crater morphology, volume, depth and diameter were measured as a function of irradiance between 0.35 and 96 GW/cm². Results show that in the vacuum, a regular trend is observed over the whole irradiance range. In air at 1 bar, below a certain irradiance, laser ablation is very similar to the vacuum case, and the ablation efficiency of copper was estimated at 0.15 ± 0.03 atom/photon. Beyond this irradiance, the laser beam propagation is strongly disrupted by the expansion of the dense plasma, and plasma shielding appears. The fraction of laser energy used for laser ablation and for plasma heating is estimated in the different irradiance regimes.

  14. Multielemental analysis of prehistoric animal teeth by laser-induced breakdown spectroscopy and laser ablation inductively coupled plasma mass spectrometry

    SciTech Connect

    Galiova, Michaela; Kaiser, Jozef; Fortes, Francisco J.; Novotny, Karel; Malina, Radomir; Prokes, Lubomir; Hrdlicka, Ales; Vaculovic, Tomas; Nyvltova Fisakova, Miriam; Svoboda, Jiri; Kanicky, Viktor; Laserna, Javier J.

    2010-05-01

    Laser-induced breakdown spectroscopy (LIBS) and laser ablation (LA) inductively coupled plasma (ICP) mass spectrometry (MS) were utilized for microspatial analyses of a prehistoric bear (Ursus arctos) tooth dentine. The distribution of selected trace elements (Sr, Ba, Fe) was measured on a 26 mmx15 mm large and 3 mm thick transverse cross section of a canine tooth. The Na and Mg content together with the distribution of matrix elements (Ca, P) was also monitored within this area. The depth of the LIBS craters was measured with an optical profilometer. As shown, both LIBS and LA-ICP-MS can be successfully used for the fast, spatially resolved analysis of prehistoric teeth samples. In addition to microchemical analysis, the sample hardness was calculated using LIBS plasma ionic-to-atomic line intensity ratios of Mg (or Ca). To validate the sample hardness calculations, the hardness was also measured with a Vickers microhardness tester.

  15. Time-of-flight spectroscopy characterization of the plasma plume from a laser-ablated potassium titanyl phosphate crystal

    NASA Astrophysics Data System (ADS)

    Ying, Minju; Wang, XiaoXiao; Cheng, Wei; Liao, Bin; Zhang, Xu

    2015-06-01

    Optical emission spectra of the plasma produced by 1.06-?m Nd:YAG laser irradiation of a potassium titanyl phosphate (KTP) crystal were recorded and analyzed in a time- and spatially resolved manner. The composition and evolution of the plasma plume were studied in low vacuum conditions. Emission lines associated with Ti(I), Ti(II) and K(I) were identified in the plasma. The delay times of emission peaks for the ablated species were investigated as a function of the observation distance from the target surface, and the velocities of these species were derived accordingly. Two emission peaks corresponding to a fast and a slow component of ablated Ti(I) were observed by optical time-of-flight spectroscopy. The origins of the two peaks and a possible mechanism for the laser ablation are discussed.

  16. Femtosecond laser ablation of dentin

    NASA Astrophysics Data System (ADS)

    Alves, S.; Oliveira, V.; Vilar, R.

    2012-06-01

    The surface morphology, structure and composition of human dentin treated with a femtosecond infrared laser (pulse duration 500 fs, wavelength 1030 nm, fluences ranging from 1 to 3 J cm-2) was studied by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The average dentin ablation threshold under these conditions was 0.6 ± 0.2 J cm-2 and the ablation rate achieved in the range 1 to 2 µm/pulse for an average fluence of 3 J cm-2. The ablation surfaces present an irregular and rugged appearance, with no significant traces of melting, deformation, cracking or carbonization. The smear layer was entirely removed by the laser treatment. For fluences only slightly higher than the ablation threshold the morphology of the laser-treated surfaces was very similar to the dentin fracture surfaces and the dentinal tubules remained open. For higher fluences, the surface was more porous and the dentin structure was partially concealed by ablation debris and a few resolidified droplets. Independently on the laser processing parameters and laser processing method used no sub-superficial cracking was observed. The dentin constitution and chemical composition was not significantly modified by the laser treatment in the processing parameter range used. In particular, the organic matter is not preferentially removed from the surface and no traces of high temperature phosphates, such as the ?-tricalcium phosphate, were observed. The achieved results are compatible with an electrostatic ablation mechanism. In conclusion, the high beam quality and short pulse duration of the ultrafast laser used should allow the accurate preparation of cavities, with negligible damage of the underlying material.

  17. Evolutions in time and space of laser ablated species by dual-laser photoabsorption spectroscopy

    SciTech Connect

    Ribiere, M.; Mees, L.; Allano, D.; Cheron, B. G. [Technopole du Madrillet, UMR 6614 CNRS (CORIA), BP 12, 76801 Saint Etienne du Rouvray (France)

    2008-08-15

    An atmospheric aluminum laser induced plasma is investigated by means of absorption and emission spectroscopies in the near ultraviolet range. The absorbed radiation is produced by a second aluminum laser induced plasma, which is generated at adjustable time delay. The measurements of both ground and resonant state number densities are derived from the fitting of the experimental 308.21 nm ({sup 2}P{sub 1/2}{sup 0}-{sup 2}D{sub 3/2}) and 396.15 nm ({sup 2}P{sub 3/2}{sup 0}-{sup 2}S{sub 1/2}) line absorption profiles on the numerical solution of the radiative transfer equation. Owing to the dominant role played by the Stark effect in the line broadening and shifting, the calculation also provides the evolution in time and in space of the free electron density along the line of sight. More classically, the same method is applied to the emission profiles which exhibit strong self-absorbed shapes. The reliability of the results derived from both absorption and emission experiments is analyzed and the origin of the asymmetric shape of the absorption lines is discussed.

  18. Laser ablation studies of concrete

    SciTech Connect

    Savina, M.; Xu, Z.; Wang, Y.; Reed, C.; Pellin, M.

    1999-10-20

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. The authors present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied using cement and high density concrete as targets. Ablation efficiency and material removal rates were determined as functions of irradiance and pulse overlap. Doped samples were also ablated to determine the efficiency with which surface contaminants were removed and captured in the effluent. The results show that the cement phase of the material melts and vaporizes, but the aggregate portion (sand and rock) fragments. The effluent consists of both micron-size aerosol particles and chunks of fragmented aggregate material. Laser-induced optical emission spectroscopy was used to analyze the surface during ablation. Analysis of the effluent showed that contaminants such as cesium and strontium were strongly segregated into different regions of the particle size distribution of the aerosol.

  19. Femtosecond Laser Ablation: Fundamentals and Applications

    E-print Network

    Harilal, S. S.

    used for Laser-induced Breakdown Spectroscopy (LIBS) for quantitative and qualitative analysis of femtosecond and picosecond lasers for analysis of materials using LIBS and LA-ICP-MS. The fundamentals in contrast to nanosecond LIBS. 6.1 Introduction Laser ablation (LA) and laser-produced plasmas (LPP) have

  20. Nanoparticles by Laser Ablation

    Microsoft Academic Search

    N. G. Semaltianos

    2010-01-01

    This review concerns nanoparticles collected in the form of nanopowder or a colloidal solution by laser ablating a solid target that lies in a gaseous or a liquid environment. The paper discusses the advantages of the method as compared with other methods for nanoparticle synthesis, outlines the factors on which the properties of the produced nanoparticles depend, explains the mechanisms

  1. Remote imaging laser-induced breakdown spectroscopy and remote cultural heritage ablative cleaning

    Microsoft Academic Search

    Rasmus Grönlund; Mats Lundqvist; Sune Svanberg

    2005-01-01

    We report, for what we believe to be the first time, on remote imaging laser-induced breakdown spectroscopy (LIBS). Measurements have been performed by using a tripled Nd:YAG laser working at 355 nm with 170 mJ pulse energy, with an expanded beam that is focused onto a target at 60 m distance. The LIBS signal is detected by using an on-axis

  2. Microwave Frequency Transitions Requiring Laser Ablated Uranium Metal Discovered Using Chirp-Pulse Fourier Transform Spectroscopy

    NASA Astrophysics Data System (ADS)

    Long, B. E.; Cooke, S. A.

    2014-06-01

    A rod of depleted uranium metal (mp = 1,132° C) has been ablated with the fundamental operating frequency of a Nd:YAG laser. The resulting ablation plume of uranium was then mixed with argon gas and expanded between the transmit/receive horn antennae of a chirp-pulse Fourier transform microwave spectrometer. The recorded spectra show nine strong transitions which are not present when the laser is not used in the experimental procedure. A series of experiments in which the backing gas conditions were altered provides evidence that the nine observed transitions are carried by the same species. Should the transitions be from one species it is most likely an asymmetric top. The transitions persist even when ultra-pure argon is used as the sole backing gas. The oxide coating of the uranium metal likely provides a source of oxygen and, presently, the ``top" candidate for the unknown molecule is UO_3, which is known to have C_2v symmetry. Double resonance experiments are planned to aid transition assignments. A plausible explanation for an elusive assignment to date is the presence of pseudo-rotation.

  3. LASER ABLATION STUDIES OF CONCRETE

    EPA Science Inventory

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-s...

  4. A comparison of laser ablation inductively coupled plasma mass spectrometry, micro X-ray fluorescence spectroscopy, and laser induced breakdown spectroscopy for the discrimination of automotive glass

    NASA Astrophysics Data System (ADS)

    Naes, Benjamin E.; Umpierrez, Sayuri; Ryland, Scott; Barnett, Cleon; Almirall, Jose R.

    2008-10-01

    Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), micro X-ray fluorescence spectroscopy (?XRF), and laser induced breakdown spectroscopy (LIBS) are compared in terms of discrimination power for a glass sample set consisting of 41 fragments. Excellent discrimination results (> 99% discrimination) were obtained for each of the methods. In addition, all three analytical methods produced very similar discrimination results in terms of the number of pairs found to be indistinguishable. The small number of indistinguishable pairs that were identified all originated from the same vehicle. The results also show a strong correlation between the data generated from the use of µXRF and LA-ICP-MS, when comparing µXRF strontium intensities to LA-ICP-MS strontium concentrations. A 266 nm laser was utilized for all LIBS analyses, which provided excellent precision (< 10% RSD for all elements and < 10% RSD for all ratios, N = 5). The paper also presents a thorough data analysis review for forensic glass examinations by LIBS and suggests several element ratios that provide accurate discrimination results related to the LIBS system used for this study. Different combinations of 10 ratios were used for discrimination, all of which assisted with eliminating Type I errors (false exclusions) and reducing Type II errors (false inclusions). The results demonstrate that the LIBS experimental setup described, when combined with a comprehensive data analysis protocol, provides comparable discrimination when compared to LA-ICP-MS and ?XRF for the application of forensic glass examinations. Given the many advantages that LIBS offers, most notably reduced complexity and reduced cost of the instrumentation, LIBS is a viable alternative to LA-ICP-MS and ?XRF for use in the forensic laboratory.

  5. Investigation of heavy-metal accumulation in selected plant samples using laser induced breakdown spectroscopy and laser ablation inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Galiová, M.; Kaiser, J.; Novotný, K.; Novotný, J.; Vaculovi?, T.; Liška, M.; Malina, R.; Stejskal, K.; Adam, V.; Kizek, R.

    2008-12-01

    Single-pulse Laser-Induced Breakdown Spectroscopy (LIBS) and Laser-Ablation Inductively Coupled Plasma Mass-Spectrometry (LA-ICP-MS) were applied for mapping the silver and copper distribution in Helianthus Annuus L. samples treated with contaminant in controlled conditions. For Ag and Cu detection the 328.07 nm Ag(I) and 324.75 nm Cu(I) lines were used, respectively. The LIBS experimental conditions (mainly the laser energy and the observation window) were optimized in order to avoid self-absorption effect in the measured spectra. In the LA-ICP-MS analysis the Ag 107 and Cu 63 isotopes were detected. The capability of these two analytical techniques for high-resolution mapping of selected trace chemical elements was demonstrated.

  6. Femtosecond laser ablation of bovine cortical bone

    NASA Astrophysics Data System (ADS)

    Cangueiro, Liliana T.; Vilar, Rui; Botelho do Rego, Ana M.; Muralha, Vania S. F.

    2012-12-01

    We study the surface topographical, structural, and compositional modifications induced in bovine cortical bone by femtosecond laser ablation. The tests are performed in air, with a Yb:KYW chirped-pulse-regenerative amplification laser system (500 fs, 1030 nm) at fluences ranging from 0.55 to 2.24 J/cm2. The ablation process is monitored by acoustic emission measurements. The topography of the laser-treated surfaces is studied by scanning electron microscopy, and their constitution is characterized by glancing incidence x-ray diffraction, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and micro-Raman spectroscopy. The results show that femtosecond laser ablation allows removing bone without melting, carbonization, or cracking. The structure and composition of the remaining tissue are essentially preserved, the only constitutional changes observed being a reduction of the organic material content and a partial recrystallization of hydroxyapatite in the most superficial region of samples. The results suggest that, within this fluence range, ablation occurs by a combination of thermal and electrostatic mechanisms, with the first type of mechanism predominating at lower fluences. The associated thermal effects explain the constitutional changes observed. We show that femtosecond lasers are a promising tool for delicate orthopaedic surgeries, where small amounts of bone must be cut with negligible damage, thus minimizing surgical trauma.

  7. Multiple target laser ablation system

    DOEpatents

    Mashburn, Douglas N. (Knoxville, TN)

    1996-01-01

    A laser ablation apparatus and method are provided in which multiple targets consisting of material to be ablated are mounted on a movable support. The material transfer rate is determined for each target material, and these rates are stored in a controller. A position detector determines which target material is in a position to be ablated, and then the controller controls the beam trigger timing and energy level to achieve a desired proportion of each constituent material in the resulting film.

  8. Multiple target laser ablation system

    DOEpatents

    Mashburn, D.N.

    1996-01-09

    A laser ablation apparatus and method are provided in which multiple targets consisting of material to be ablated are mounted on a movable support. The material transfer rate is determined for each target material, and these rates are stored in a controller. A position detector determines which target material is in a position to be ablated, and then the controller controls the beam trigger timing and energy level to achieve a desired proportion of each constituent material in the resulting film. 3 figs.

  9. High spatial resolution mapping of deposition layers on plasma facing materials by laser ablation microprobe time-of-flight mass spectroscopy

    SciTech Connect

    Xiao, Qingmei; Li, Cong; Hai, Ran; Zhang, Lei; Feng, Chunlei; Ding, Hongbin, E-mail: hding@dlut.edu.cn [School of Physics and Optical Electronic Technology, Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Chinese Ministry of Education, Dalian University of Technology, Dalian 116024 (China); Zhou, Yan; Yan, Longwen; Duan, Xuru [Southwestern Institute of Physics, P.O. Box 432, No. 3 South Section 3, Circle Road 2, Chengdu 610041, Sichuan (China)

    2014-05-15

    A laser ablation microprobe time-of-flight mass spectroscopy (LAM-TOF-MS) system with high spatial resolution, ?20 nm in depth and ?500 ?m or better on the surface, is developed to analyze the composition distributions of deposition layers on the first wall materials or first mirrors in tokamak. The LAM-TOF-MS system consists of a laser ablation microprobe combined with a TOF-MS and a data acquisition system based on a LabVIEW program software package. Laser induced ablation combined with TOF-MS is an attractive method to analyze the depth profile of deposited layer with successive laser shots, therefore, it can provide information for composition reconstruction of the plasma wall interaction process. In this work, we demonstrate that the LAM-TOF-MS system is capable of characterizing the depth profile as well as mapping 2D composition of deposited film on the molybdenum first mirror retrieved from HL-2A tokamak, with particular emphasis on some of the species produced during the ablation process. The presented LAM-TOF-MS system provides not only the 3D characterization of deposition but also the removal efficiency of species of concern.

  10. Forensic analysis of printing inks using tandem Laser Induced Breakdown Spectroscopy and Laser Ablation Inductively Coupled Plasma Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Subedi, Kiran; Trejos, Tatiana; Almirall, José

    2015-01-01

    Elemental analysis, using either LA-ICP-MS or LIBS, can be used for the chemical characterization of materials of forensic interest to discriminate between source materials originating from different sources and also for the association of materials known to originate from the same source. In this study, a tandem LIBS/LA-ICP-MS system that combines the benefits of both LIBS and LA-ICP-MS was evaluated for the characterization of samples of printing inks (toners, inkjets, intaglio and offset.). The performance of both laser sampling methods is presented. A subset of 9 black laser toners, 10 colored (CMYK) inkjet samples, 12 colored (CMYK) offset samples and 12 intaglio inks originating from different manufacturing sources were analyzed to evaluate the discrimination capability of the tandem method. These samples were selected because they presented a very similar elemental profile by LA-ICP-MS. Although typical discrimination between different ink sources is found to be > 99% for a variety of inks when only LA-ICP-MS was used for the analysis, additional discrimination was achieved by combining the elemental results from the LIBS analysis to the LA-ICP-MS analysis in the tandem technique, enhancing the overall discrimination capability of the individual laser ablation methods. The LIBS measurements of the Ca, Fe, K and Si signals, in particular, improved the discrimination for this specific set of different ink samples previously shown to exhibit very similar LA-ICP-MS elemental profiles. The combination of these two techniques in a single setup resulted in better discrimination of the printing inks with two distinct fingerprint spectra, providing information from atomic/ionic emissions and isotopic composition (m/z) for each ink sample.

  11. Laser Ablation for Medical Applications

    NASA Astrophysics Data System (ADS)

    Hayashi, Ken-Ichi

    Medical applications of laser are measurement, laser surgery, in-situ monitoring, and processing of medical devices. In this paper, author briefly reviews the trends of medical applications, describes some new applications, and then discuss about the future trends and problems of medical applications. At present, the domestic market of laser equipment for medical applications is nearly 1/10 of that for industrial applications, which has registered significant growth continuously. Laser surgery as a minimum invasive surgery under arthroscope is expected to decrease the pain of patients. Precise processing such as cutting and welding is suitable for manufacturing medical devices. Pulsed laser deposition has been successfully applied to the thin film coating. The corneal refractive surgery by ArF excimer laser has been widely accepted for its highly safe operation. Laser ablation for retinal implant in the visual prosthesis is one of the promising applications of laser ablation in medicine. New applications with femtosecond laser are expected in the near future.

  12. Ultrasonic characterization of laser ablation

    NASA Astrophysics Data System (ADS)

    Smith, J. A.; Telschow, K. L.

    When a pulsed laser beam strikes the surface of an absorbing material, ultrasonic waves are generated due to thermoelectric expansion and, at higher laser power densities, ablation of the material. These sound generation mechanisms have been the subject of numerous theoretical and experimental studies and are now fairly well understood. In particular, it has been established that at low power densities the thermoelastic mechanism is well described by a surface center of expansion. This mechanism produces a characteristic waveform whose amplitude is proportional to the energy absorbed from the laser pulse and also dependent on the thermal and elastic properties of the material. The ablation ultrasonic source can be described by a point normal force acting on the material surface. For laser power densities near the ablation onset, the time dependence of the source is that of the laser pulse. The resultant waveform recorded on epicenter (source and detector collinear) has a sharp peak determined by the momentum impulse delivered to the material by the ablation process. Particularly in the near ablation onset region, this ultrasonic displacement peak can be used to characterize the ablation process occurring at the material surface. The onset power density for ablation and subsequent ablation dependence on power density are material dependent and thought to be a function of the heat capacity and thermal conductivity of the material. With this in mind, it is possible that these ablation signals could be used to characterize material microstructures, and perhaps material mechanical properties such as hardness, through microstructural changes of the material thermal parameters. This paper explores this question for samples of Type 304 stainless steel with microstructures controlled through work hardening and annealing.

  13. Diagnostics of Pulsed Laser Ablation

    Microsoft Academic Search

    Palanikumaran Sakthivel

    1995-01-01

    We present the results of optical and ion probe diagnostics of pulsed laser-deposition. The dynamics of laser-ablated plumes and the effect of ambient pressure, laser spot-size, laser fluence and in-situ ring electrode have been investigated in detail, in time-resolved as well as time-integrated modes. Ion probes were used to study the ionic content of the plume. The role of ions

  14. Laser ablation based fuel ignition

    DOEpatents

    Early, J.W.; Lester, C.S.

    1998-06-23

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition. 3 figs.

  15. Laser ablation based fuel ignition

    DOEpatents

    Early, James W. (Los Alamos, NM); Lester, Charles S. (San Juan Pueblo, NM)

    1998-01-01

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition.

  16. Dynamical Study of Femtosecond-Laser-Ablated Liquid-Aluminum Nanoparticles Using Spatiotemporally Resolved X-Ray-Absorption Fine-Structure Spectroscopy

    SciTech Connect

    Oguri, Katsuya; Okano, Yasuaki; Nishikawa, Tadashi; Nakano, Hidetoshi [NTT Basic Research Laboratories, Nippon Telegraph and Telephone Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198 (Japan)

    2007-10-19

    We study the temperature evolution of aluminum nanoparticles generated by femtosecond laser ablation with spatiotemporally resolved x-ray-absorption fine-structure spectroscopy. We successfully identify the nanoparticles based on the L-edge absorption fine structure of the ablation plume in combination with the dependence of the edge structure on the irradiation intensity and the expansion velocity of the plume. In particular, we show that the lattice temperature of the nanoparticles is estimated from the L-edge slope, and that its spatial dependence reflects the cooling of the nanoparticles during plume expansion. The results reveal that the emitted nanoparticles travel in a vacuum as a condensed liquid phase with a lattice temperature of about 2500 to 4200 K in the early stage of plume expansion.

  17. LASER ABLATION-INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPY STUDY AT THE 222-S LABORATORY USING HOT-CELL GLOVE BOX PROTOTYPE SYSTEM

    SciTech Connect

    LOCKREM LL; OWENS JW; SEIDEL CM

    2009-03-26

    This report describes the installation, testing and acceptance of the Waste Treatment and Immobilization Plant procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste samples in a hot cell environment. The 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.

  18. LASER ABLATION-INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPY STUDY AT THE 222-S LABORATORY USING HOT-CELL GLOVE BOX PROTOTYPE SYSTEM

    SciTech Connect

    SEIDEL CM; JAIN J; OWENS JW

    2009-02-23

    This report describes the installation, testing, and acceptance of the Waste Treatment and Immobilization Plant (WTP) procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste (HLW) samples in a hot cell environment. The work was completed by the Analytical Process Development (APD) group in accordance with Task Order 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S Laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.

  19. Laser ablation: Fundamental principles for analytical applications

    SciTech Connect

    Russo, R.E.; Mao, X.L.; Shannon, M.A. [Lawrence Berkeley Lab., CA (United States)] [and others

    1994-12-31

    This paper will discuss fundamental issues influencing the coupling of laser energy to solid surfaces for accurate and efficient chemical analysis. Results from several monitoring techniques are correlated to demonstrate the changes in laser sampling mechanisms as a function of incident power density, the primary parameter influencing the interaction. Inductive Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) is an excellent system for studying laser ablation. The ICP-AES signal intensity is proportional to the power of laser power density (P{sub n}), with two very different power dependencies. At P < 3x108 W/cm2, the slope n is about 3.5 and at P > 3x108 W/cm2 the slope n is about 1.3. These results suggest significant changes in the energy coupling to the material surface as a function of power density. The reduced power dependence, i.e., mass ablation rate, at the higher power densities may be indicative of plasma shielding. Results from ICP-AES measurement are correlated with those from acoustics, laser induced plasma emission intensity show the same two slope behaviors as the ICP-AES data. There also is strong correlation between ICP and laser induced plasma emission intensities over the power density region. All the monitoring techniques show a turning point at about 3x108 W/cm2, in which the mass ablation rate decreases. The correlations of data from these various techniques are discussed in terms of understanding the laser ablation processes for chemical analysis applications.

  20. Novel applications for laser ablation of photopolymers

    NASA Astrophysics Data System (ADS)

    Lippert, T.; David, C.; Hauer, M.; Masubuchi, T.; Masuhara, H.; Nomura, K.; Nuyken, O.; Phipps, C.; Robert, J.; Tada, T.; Tomita, K.; Wokaun, A.

    2002-01-01

    The ablation characteristics of various polymers were studied at low and high fluences. The polymers can be divided into three groups, polymers containing triazene groups, polyesters with cinnamylidenemalonyl groups, and polyimide (PI) as reference polymer. The polymers containing the photochemically most active group (triazene) are also the polymers with the lowest threshold of ablation and the highest etch rates, followed by the designed polyesters and then PI. The triazene-polymer (TP) was studied at low fluences with additional techniques. UV-Vis spectroscopy and TOF-MS reveal that the triazene-chromophore decomposes also upon irradiation with fluences below the threshold of ablation. At the threshold fluence, a pronounced change is detected, i.e., an approximately 10 times higher decomposition rate. Nanosecond surface interferometry was applied to detect changes of the surface morphology of the TP and PI after irradiation with fluences above the threshold of ablation. In the case of the TP, no swelling of the surface is observed and etching starts and ends with the laser pulse, while a very pronounced swelling is detected for PI. The clear difference between PI and the designed polymers can be explained by a pronounced thermal part in the ablation mechanism of PI, while photochemical activities are more important for the TP. The combination of phase masks and the TP allows an efficient fabrication of three-dimensional topographies using laser ablation. The TP also reveals superior properties for applications in the near-IR. The carbon-doped polymer shows properties that are useful for the application of polymers in laser plasma thrusters for microsatellites.

  1. Debris of potassium-magnesium silicate glass generated by femtosecond laser-induced ablation in air: An analysis by near edge X-ray absorption spectroscopy, micro Raman and energy dispersive X-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Grehn, M.; Seuthe, T.; Reinhardt, F.; Höfner, M.; Griga, N.; Eberstein, M.; Bonse, J.

    2014-05-01

    The redeposited material (debris) resulting from ablation of a potassium-magnesium silicate glass upon scanning femtosecond laser pulse irradiation (130 fs, 800 nm) in air environment is investigated by means of three complementary surface analytical methods. Changes in the electronic band structure of the glass constituent Magnesium (Mg) were identified by X-ray Absorption Near Edge Structure spectroscopy (XANES) using synchrotron radiation. An up-shift of ?0.8 eV of a specific Magnesium K-edge absorption peak in the spectrum of the redeposited material along with a significant change in its leading edge position was detected. In contrast, the surface left after laser ablation exhibits a downshift of the peak position by ?0.9 eV. Both observations may be related to a change of the Mg coordinative state of the laser modified/redeposited glass material. The presence of carbon in the debris is revealed by micro Raman spectroscopy (?-RS) and was confirmed by energy dispersive X-ray spectroscopy (EDX). These observations are attributed to structural changes and chemical reactions taking place during the ablation process.

  2. Endometrial ablation

    MedlinePLUS

    Hysteroscopy-endometrial ablation; Laser thermal ablation; Endometrial ablation-radiofrequency; Endometrial ablation-thermal balloon ablation; Rollerball ablation; Hydrothermal ablation; Novasure ablation

  3. Evolutions in time and space of laser ablated species by dual-laser photo-absorption spectroscopy

    E-print Network

    Boyer, Edmond

    76801 Saint Etienne du Rouvray FRANCE ribiere@coria.fr, cheron@coria.fr An atmospheric aluminum laser,14 The control of these processes requires the knowledge of the plasma plume expansion dynamic(II) number densities from a two-zone model. Sakka et al. 23,24 and Karabourniotis 25 has measured the density

  4. Laser ablation of YBa sub 2 Cu sub 3 O sub 7 minus. delta. as probed by laser-induced fluorescence spectroscopy

    SciTech Connect

    Otis, C.E. (IBM Endicott Laser Spectroscopy Laboratory, 1701 North Street, Endicott, New York (USA)); Dreyfus, R.W. (IBM Research Division, Thomas J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York (USA))

    1991-10-07

    Ground-state populations of cationic and neutral Y, Ba, Cu, and neutral YO, BaO, and CuO are monitored by laser-induced fluorescence during laser ablation of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. 193-nm photons completely dissociate CuO allowing the observation of a subsequent reaction of the Cu atom with O{sub 2} to form CuO. As a function of O{sub 2} pressure, the CuO signal increases to a maximum at approximately 120 mTorr of O{sub 2}, presumably minimizing {delta}, and then falls to negligible levels by 400 mTorr. Ablation at 248 and 351 nm dissociates a smaller fraction of the CuO, i.e., nascent CuO is observed in the absence of O{sub 2}.

  5. Characterization of products of excimer laser ablation of collagen

    NASA Astrophysics Data System (ADS)

    Ediger, Marwood N.; Hahn, D. W.; Pettit, George H.

    1995-05-01

    The presence of hydroxyl radicals in the ArF excimer ablation sites in bovine corneal tissue has been investigated by laser-induced fluorescence and Raman spectroscopy. Raman spectroscopy has also been applied to examine the time-resolved temperature of the water component of the ablation site as well as the spatially selective measurement of surface desiccation. Results indicate that the hydroxyl radical is not generate in abundance during the ablation process. Also, Raman monitoring of the ablation site demonstrates no detectable heating during ArF irradiation, while elevated temperatures are observed following exposure of the corneal surface to a Er:YAG laser. Finally, comparison of C-H and O-H Raman bands shows potential utility as a spatially selective means for monitoring tissue hydration.

  6. Observation of femtosecond-laser-induced ablation plumes of aluminum using space- and time-resolved soft x-ray absorption spectroscopy

    SciTech Connect

    Okano, Yasuaki; Oguri, Katsuya; Nishikawa, Tadashi; Nakano, Hidetoshi [NTT Basic Research Laboratories, Nippon Telegraph and Telephone Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198 (Japan)

    2006-11-27

    The dynamics of the laser ablation plume expansion of aluminum was investigated by using space- and time-resolved soft x-ray absorption spectroscopy. Blueshifts of the Al L-shell photoabsorption edge indicating the state of aluminum were observed in the plumes, which were generated by irradiating an aluminum target with 120 fs near-infrared pulses at an intensity of 10{sup 14} W/cm{sup 2}. The spatiotemporal evolution of the plumes exhibited a multilayer structure consisting of vaporized aluminum and condensed aluminum particles, following the expansion of plasma, with expansion velocities of 10{sup 4} m/s for the atomic state and 10{sup 3} m/s for the condensed state.

  7. Heterodyne laser spectroscopy system

    SciTech Connect

    Wyeth, R.W.; Paisner, J.A.; Story, T.

    1989-03-28

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency and the like, and provides spectral analysis of a laser beam.

  8. PULSED LASER ABLATION OF CEMENT AND CONCRETE

    EPA Science Inventory

    Laser ablation was investigated as a means of removing radioactive contaminants from the surface and near-surface regions of concrete from nuclear facilities. We present the results of ablation tests on cement and concrete samples using a pulsed Nd:YAG laser with fiber optic beam...

  9. Laser Navigation for Radiofrequency Ablation

    SciTech Connect

    Varro, Zoltan; Locklin, Julia K., E-mail: bwood@nih.gov; Wood, Bradford J. [National Institutes of Health, Warren G. Magnuson Clinical Center, Diagnostic Radiology Department (United States)

    2004-09-15

    A 45-year-old male with renal cell carcinoma secondary to von-Hippel Lindau (VHL) disease presented for radiofrequency ablation (RFA) of kidney tumors. Due to his prior history of several partial nephrectomies and limited renal reserve, RFA was chosen because of its relatively nephron-sparing nature. A laser guidance device was used to help guide probe placement in an attempt to reduce procedure time and improve targeting accuracy. The device was successful at guiding needle placement, as both tumors were located with a single pass. Follow-up CT scan confirmed accurate needle placement, showing an area of coagulation necrosis covering the previously seen tumor.

  10. Laser Spectroscopy

    NASA Astrophysics Data System (ADS)

    Katori, H.; Yoneda, H.; Nakagawa, K.; Shimizu, F.

    2010-02-01

    Anderson localization of matter-waves in a controlled disorder: a quantum simulator? / A. Aspect ... [et al.] -- Squeezing and entanglement in a Bose-Einstein condensate / C. Gross ... [et al.] -- New physics in dipolar Bose-Einstein condensates / Y. Kawaguchi, H. Saito, and M. Ueda -- Observation of vacuum fluctuations in a spinor Bose-Einstein condensate / C. Klempt ... [et al.] -- Negative-index media for matter waves / F. Perales ... [et al.] -- Entanglement of two individual atoms using the Rydberg blockade / A. Browaeys ... [et al.] -- Array of mesoscopic ensembles on a magnetic atom chip / A. F. Tauschinsky ... [et al.] -- Stability of the proton-to-electron mass ratio tested with molecules using an optical link to primary clock / A. Amy-Klein ... [et al.] -- Metastable helium: lifetime measurements using cold atoms as a test of QED / K. G. H. Baldwin ... [et al.] -- Optical lattice clocks with single occupancy bosons and spin-polarized fermions toward 10[symbol] accuracy / M. Takamoto ... [et al.] -- Frequency measurements of Al[symbol] and Hg[symbol] optical standards / W. M. Itano ... [et al.] -- Switching of light with light using cold atoms inside a hollow optical fiber / M. Bajcsy ... [et al.] -- Room-temperature atomic ensembles for quantum memory and magnetometry / K. Jensen ... [et al.] -- Components for multi-photon non-classical state preparation and measurement / G. Puentes ... [et al.] -- Quantum field state measurement and reconstruction in a cavity by quantum nondemolition photon counting / M. Brune ... [et al.] -- XUV frequency comb spectroscopy / C. Gohle ... [et al.] -- Ultrahigh-repetition-rate pulse train with absolute-phase control produced by an adiabatic raman process / M. Katsuragawa ... [et al.] -- Strongly correlated bosons and fermions in optical lattices / S. Will ... [et al.] -- Bragg spectroscopy of ultracold bose gases in optical lattices / L. Fallani ... [et al.] -- Synthetic quantum many-body systems / C. Guerlin ... [et al.] -- Ultracold Ytterbium atoms in optical lattices / S. Sugawa ... [et al.] -- Ultracold polar molecules in the rovibrational ground state / J. Deiglmayr ... [et al.] -- Polar molecules near quantum degeneracy / J. Ye and D. S. Jin -- Production of a quantum gas of rovibronic ground-state molecules in an optical lattice / J. G. Danzl ... [et al.] -- Recent progress in x-ray nonlinear optics / K. Tamasaku, K. Sawada, and T. Ishikawa -- Gas in scattering media absorption spectroscopy - laser spectroscopy in unconventional environments / S. Svanberg -- Laser spectroscopy on relativistic ion beams / S. Reinhardt ... [et al.] -- Single frequency microcavity lasers and applications / L. Xu ... [et al.].

  11. MicroRaman study of laser ablated GaAs

    SciTech Connect

    Garcia, C.; Jimenez, J.; Prieto, A.C.; Ramos, J.; Sanz, L.F.

    1995-12-31

    Morphologic and structural changes induced by UV pulsed laser beams on GaAs are studied by means of surface inspection (optical interferometry) and MicroRaman spectroscopy. Crystal order and chemical composition (dopant distribution) are shown to be changed by the ablation.

  12. Fractal Character of Titania Nanoparticles Formed by Laser Ablation

    SciTech Connect

    Musaev, O.; Midgley, A; Wrobel, J; Yan, J; Kruger, M

    2009-01-01

    Titania nanoparticles were fabricated by laser ablation of polycrystalline rutile in water at room temperature. The resulting nanoparticles were analyzed with x-ray diffraction, Raman spectroscopy, and transmission electron microscopy. The electron micrograph image of deposited nanoparticles demonstrates fractal properties.

  13. Spectroscopic measurement of plume emission from femtosecond laser ablation

    Microsoft Academic Search

    Denis Moreau; O Albert; R Benzerga; C Boulmer-Leborgne; E Millon; J Perrière; J Etchepare

    2004-01-01

    We present a time and space resolved emission spectroscopy technique that enables a full characterisation in three dimensions density of emitting species generated by femtosecond pulsed laser ablation. Applied to Al neutral atoms, it reveals a population that, at the lowest fluences used, can be roughly described by a half range Maxwell–Boltzmann function. This simple configuration evolves towards a more

  14. Dynamics of mid-infrared femtosecond laser resonant ablation

    NASA Astrophysics Data System (ADS)

    Pang, Dongqing; Li, Yunxuan; Wang, Qingyue

    2014-06-01

    Resonant ablation is beneficial to avoiding uncontrollable subsurface damages in the laser ablation of polymers. In this paper the dynamics of mid-infrared laser resonant ablation of polylactic acid and toluene was calculated by using fluid dynamic equations. The merits and drawbacks of mid-infrared femtosecond laser resonant ablation of high molecular weight polymers have been discussed.

  15. Chemically assisted laser ablation ICP mass spectrometry.

    PubMed

    Hirata, Takafumi

    2003-01-15

    A new laser ablation technique combined with a chemical evaporation reaction has been developed for elemental ratio analysis of solid samples using an inductively coupled plasma mass spectrometer (ICPMS). Using a chemically assisted laser ablation (CIA) technique developed in this study, analytical repeatability of the elemental ratio measurement was successively improved. To evaluate the reliability of the CLA-ICPMS technique, Pb/U isotopic ratios were determined for zircon samples that have previously been analyzed by other techniques. Conventional laser ablation for Pb/U shows a serious elemental fractionation during ablation mainly due to the large difference in elemental volatility between Pb and U. In the case of Pb/U ratio measurement, a Freon R-134a gas (1,1,1,2-tetrafluoroethane) was introduced into the laser cell as a fluorination reactant. The Freon gas introduced into the laser cell reacts with the ablated sample U, and refractory U compounds are converted to a volatile U fluoride compound (UF6) under the high-temperature condition at the ablation site. This avoids the redeposition of U around the ablation pits. Although not all the U is reacted with Freon, formation of volatile UF compounds improves the transmission efficiency of U. Typical precision of the 206Pb/238U ratio measurement is 3-5% (2sigma) for NIST SRM 610 and Nancy 91500 zircon standard, and the U-Pb age data obtained here show good agreement within analytical uncertainties with the previously reported values. Since the observed Pb/U ratio for solid samples is relatively insensitive to laser power and ablation time, optimization of ablation conditions or acquisition parameters no longer needs to be performed on a sample-to-sample basis. PMID:12553756

  16. Laser Ablation of Silk Protein (Fibroin) Films

    NASA Astrophysics Data System (ADS)

    Tsuboi, Yasuyuki; Adachi, Hisanori; Yamada, Kazushi; Miyasaka, Hiroshi; Itaya, Akira

    2002-07-01

    Fibroin is the main protein component of silk and is expected to have functional applications in bioelectronics and medicine. We investigated nanosecond (ns) pulsed laser ablation of solid fibroin films with/without a dye as a photosensitizer. Laser lights at 248 nm and 532/355/351 nm excited the peptide bond of fibroin and the dye, respectively. The neat film irradiated at 248 nm was scarcely accessible to etching and swelling, and instead, a microscopic pattern (structure) was formed. In contrast, for ablation of the doped film at 532/355/351 nm, we found marked swelling (height ˜500 ?m) and deep etching (depth ˜10 ?m) on the irradiated surfaces. The dye-photosensitized ablation was brought about by a photothermal mechanism, whereas ablation of neat films may be induced by another process, such as a photochemical one. The ablation processes are discussed in terms of the properties of fibroin and the mode of excitation.

  17. Retained foreign body after laser ablation.

    PubMed

    Ren, Shiyan; Liu, Peng; Wang, Wei; Yang, Yuguan

    2012-01-01

    Laser ablation for varicose veins is a common practice, and postoperative complications may happen. A retained foreign body could be left accidently in the treated leg. It is rarely reported in literature. We herein describe two cases of retained foreign body during the laser ablation for varicose veins. One patient with varicose veins received laser therapy 5 years earlier, and had experienced discomfort and pain. After investigation, an overlooked sheath fragment was removed surgically from the leg. Another patient with varicose veins had discomfort after laser ablation for 8 days, and has been asymptomatic after the removal of the retained foreign body in the leg. The essential preventive approach include to pinpoint the site of the tip of fiberoptic laser fiber and pull 1 to 2 cm of the sheath out of the patient, then withdrawal the fiberoptic fiber and sheath simultaneously. A white flash light in the trunk of the fiberoptic laser fiber is an important warning signal of an erroneous manipulation during the operation. The surgeon should routinely check the intact sheath and fiberoptic fiber after laser ablation. In conclusion, retained foreign body can be prevented by following some practical tips during laser ablation. PMID:23294067

  18. Subpicosecond laser ablation of dental enamel

    NASA Astrophysics Data System (ADS)

    Rode, A. V.; Gamaly, E. G.; Luther-Davies, B.; Taylor, B. T.; Dawes, J.; Chan, A.; Lowe, R. M.; Hannaford, P.

    2002-08-01

    Laser ablation of dental enamel with subpicosecond laser pulses has been studied over the intensity range of (0.1-1.4) x1014 W/cm2 using 95 and 150 fs pulses at a pulse repetition rate of 1 kHz. The experimentally determined ablation threshold of 2.2plus-or-minus0.1 J/cm2 was in good agreement with theoretical predictions based on an electrostatic ablation model. The ablation rate increased linearly with the laser fluence for up to 15 times the ablation threshold. The absence of collateral damage was observed using optical and scanning electron microscopy. Pulpal temperature measurements showed an increase of about 10 degC during the 200 s course of ablation. However, air cooling at a rate of 5 l/min resulted in the intrapulpal temperature being maintained below the pulpal damage threshhold of 5.5 degC. The material removal rates for subpicosecond precision laser ablation of dental enamel are compared with other techniques.

  19. Analytical procedure for characterization of medieval wall-paintings by X-ray fluorescence spectrometry, laser ablation inductively coupled plasma mass spectrometry and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Syta, Olga; Rozum, Karol; Choi?ska, Marta; Zieli?ska, Dobrochna; ?ukowska, Gra?yna Zofia; Kijowska, Agnieszka; Wagner, Barbara

    2014-11-01

    Analytical procedure for the comprehensive chemical characterization of samples from medieval Nubian wall-paintings by means of portable X-ray fluorescence (pXRF), laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) and Raman spectroscopy (RS) was proposed in this work. The procedure was used for elemental and molecular investigations of samples from archeological excavations in Nubia (modern southern Egypt and northern Sudan). Numerous remains of churches with painted decorations dated back to the 7th-14th century were excavated in the region of medieval kingdoms of Nubia but many aspects of this art and its technology are still unknown. Samples from the selected archeological sites (Faras, Old Dongola and Banganarti) were analyzed in the form of transfers (n = 26), small fragments collected during the excavations (n = 35) and cross sections (n = 15). XRF was used to collect data about elemental composition, LA-ICPMS allowed mapping of selected elements, while RS was used to get the molecular information about the samples. The preliminary results indicated the usefulness of the proposed analytical procedure for distinguishing the substances, from both the surface and sub-surface domains of the wall-paintings. The possibility to identify raw materials from the wall-paintings will be used in the further systematic, archeometric studies devoted to the detailed comparison of various historic Nubian centers.

  20. Effects of Laser Wavelength on Ablator Testing

    NASA Technical Reports Server (NTRS)

    White, Susan M.

    2014-01-01

    Wavelength-dependent or spectral radiation effects are potentially significant for thermal protection materials. NASA atmospheric entry simulations include trajectories with significant levels of shock layer radiation which is concentrated in narrow spectral lines. Tests using two different high powered lasers, the 10.6 micron LHMEL I CO2 laser and the near-infrared 1.07 micron fiber laser, on low density ablative thermal protection materials offer a unique opportunity to evaluate spectral effects. Test results indicated that the laser wavelength can impact the thermal response of an ablative material, in terms of bond-line temperatures, penetration times, mass losses, and char layer thicknesses.

  1. Nanoparticle formation by femtosecond laser ablation

    Microsoft Academic Search

    J. Perrière; C. Boulmer-Leborgne; R. Benzerga; S. Tricot

    2007-01-01

    The main features of ultra-short laser ablation of various materials (metals, semiconductors or insulators) have been studied through the complementary analyses of the plasma plume induced by laser irradiation, and of the deposited films. The generation of nanoparticles (in the 10-100 nm range) was observed and these findings were investigated in order to obtain information on the relevant parameters governing

  2. Neutrals ejection in intense femtosecond laser ablation.

    PubMed

    Hu, Haofeng; Wang, Xiaolei; Zhai, Hongchen

    2011-01-15

    Time-resolved shadowgraphs and holograms of intense femtosecond laser ablation of aluminum are reported. The different bending trends of interference fringes are found in the ablations of aluminum and other materials at probe wavelengths of 400 and 800 nm, for the first time to our knowledge, which could be attributed to the ejection of massive neutral droplets induced by critical-point phase separation during the second material ejection. PMID:21263474

  3. Plasma luminescence feedback control system for precise ultrashort pulse laser tissue ablation

    SciTech Connect

    Kim, B.M.; Feit, M.D.; Rubenchick, A.M.; Gold, D.M.; Darrown, C.B.; Da Silva, L.B.

    1998-01-01

    Plasma luminescence spectroscopy was used for precise ablation of bone tissue without damaging nearby soft tissue using ultrashort pulse laser (USPL). Strong contrast of the luminescence spectra between bone marrow and spinal cord provided the real time feedback control so that only bone tissue can be selectively ablated while preserving the spinal cord.

  4. Boron carbonitride films deposited by pulsed laser ablation

    Microsoft Academic Search

    A. Perrone; A. P Caricato; A Luches; M Dinescu; C Ghica; V Sandu; A Andrei

    1998-01-01

    Boron carbonitride (BCN) thin films were deposited on Si (100) substrates at room temperature by sequential pulsed laser ablation (PLA) of graphite and hexagonal boron nitride (h-BN) targets in vacuum and in nitrogen atmosphere in the pressure range 1–100 Pa. Different analysis techniques as transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) pointed out the synthesis

  5. Femtosecond laser lithotripsy: feasibility and ablation mechanism

    NASA Astrophysics Data System (ADS)

    Qiu, Jinze; Teichman, Joel M. H.; Wang, Tianyi; Neev, Joseph; Glickman, Randolph D.; Chan, Kin Foong; Milner, Thomas E.

    2010-03-01

    Light emitted from a femtosecond laser is capable of plasma-induced ablation of various materials. We tested the feasibility of utilizing femtosecond-pulsed laser radiation (?=800 nm, 140 fs, 0.9 mJ/pulse) for ablation of urinary calculi. Ablation craters were observed in human calculi of greater than 90% calcium oxalate monohydrate (COM), cystine (CYST), or magnesium ammonium phosphate hexahydrate (MAPH). Largest crater volumes were achieved on CYST stones, among the most difficult stones to fragment using Holmium:YAG (Ho:YAG) lithotripsy. Diameter of debris was characterized using optical microscopy and found to be less than 20 ?m, substantially smaller than that produced by long-pulsed Ho:YAG ablation. Stone retropulsion, monitored by a high-speed camera system with a spatial resolution of 15 ?m, was negligible for stones with mass as small as 0.06 g. Peak shock wave pressures were less than 2 bars, measured by a polyvinylidene fluoride (PVDF) needle hydrophone. Ablation dynamics were visualized and characterized with pump-probe imaging and fast flash photography and correlated to shock wave pressures. Because femtosecond-pulsed laser ablates urinary calculi of soft and hard compositions, with micron-sized debris, negligible stone retropulsion, and small shock wave pressures, we conclude that the approach is a promising candidate technique for lithotripsy.

  6. Surface Decontamination Using Laser Ablation Process - 12032

    SciTech Connect

    Moggia, Fabrice; Lecardonnel, Xavier; Damerval, Frederique [AREVA, Back End Business Group, Clean Up Business Unit (France)

    2012-07-01

    A new decontamination method has been investigated and used during two demonstration stages by the Clean-Up Business Unit of AREVA. This new method is based on the use of a Laser beam to remove the contaminants present on a base metal surface. In this paper will be presented the type of Laser used during those tests but also information regarding the efficiency obtained on non-contaminated (simulated contamination) and contaminated samples (from the CEA and La Hague facilities). Regarding the contaminated samples, in the first case, the contamination was a quite thick oxide layer. In the second case, most of the contamination was trapped in dust and thin grease layer. Some information such as scanning electron microscopy (SEM), X-Ray scattering spectroscopy and decontamination factors (DF) will be provided in this paper. Laser technology appears to be an interesting one for the future of the D and D applications. As shown in this paper, the results in terms of efficiency are really promising and in many cases, higher than those obtained with conventional techniques. One of the most important advantages is that all those results have been obtained with no generation of secondary wastes such as abrasives, chemicals, or disks... Moreover, as mentioned in introduction, the Laser ablation process can be defined as a 'dry' process. This technology does not produce any liquid waste (as it can be the case with chemical process or HP water process...). Finally, the addition of a vacuum system allows to trap the contamination onto filters and thus avoiding any dissemination in the room where the process takes place. The next step is going to be a commercial use in 2012 in one of the La Hague buildings. (authors)

  7. From Laser Desorption to Laser Ablation of Biopolymers

    NASA Astrophysics Data System (ADS)

    Franz, Hillenkamp

    1998-03-01

    For selected indications laser ablation and cutting of biological tissues is clinical practice. Preferentially lasers with emission wavelengths in the far UV and the mid IR are used, for which tissue absorption is very high. Morphologically the ablation sites look surprisingly similar for the two wavelength ranges, despite of the very different prim y putative interaction mechanisms. Ablation depth as a function of fluence follows a sigmoidal curve. Even factors below the nominal ablation threshold superficial layers of material get removed from the surface. This is the fluence range for Matrix-Assisted Laser Desorption/Ionization (MALDI). Evidence will be presented which suggest that strong similarities exist between the desorption and ablation processes both for UV- as well as for IR-wavelengths.

  8. The rotational spectrum of CuCCH(X~ 1?+): A Fourier transform microwave discharge assisted laser ablation spectroscopy and millimeter/submillimeter study

    NASA Astrophysics Data System (ADS)

    Sun, M.; Halfen, D. T.; Min, J.; Harris, B.; Clouthier, D. J.; Ziurys, L. M.

    2010-11-01

    The pure rotational spectrum of CuCCH in its ground electronic state (X˜ ?1+) has been measured in the frequency range of 7-305 GHz using Fourier transform microwave (FTMW) and direct absorption millimeter/submillimeter methods. This work is the first spectroscopic study of CuCCH, a model system for copper acetylides. The molecule was synthesized using a new technique, discharge assisted laser ablation spectroscopy (DALAS). Four to five rotational transitions were measured for this species in six isotopologues (C63uCCH, C65uCCH, C63uC13CH, C63uCC13H, C63uC13C13H, and C63uCCD); hyperfine interactions arising from the copper nucleus were resolved, as well as smaller splittings in CuCCD due to deuterium quadrupole coupling. Five rotational transitions were also recorded in the millimeter region for C63uCCH and C65uCCH, using a Broida oven source. The combined FTMW and millimeter spectra were analyzed with an effective Hamiltonian, and rotational, electric quadrupole (Cu and D) and copper nuclear spin-rotation constants were determined. From the rotational constants, an rm(2) structure for CuCCH was established, with rCu?C=1.8177(6) Å, rC?C=1.2174(6) Å, and rC?H=1.046(2) Å. The geometry suggests that CuCCH is primarily a covalent species with the copper atom singly bonded to the C?C?H moiety. The copper quadrupole constant indicates that the bonding orbital of this atom may be sp hybridized. The DALAS technique promises to be fruitful in the study of other small, metal-containing molecules of chemical interest.

  9. Foundations of Laser Spectroscopy

    Microsoft Academic Search

    Stig Stenholm; John E. Thomas

    1984-01-01

    Presents the theoretical foundations of steady state laser spectroscopy at an elementary level. General foundations and specific features of nonlinear effects are summarized, laser operation and laser spectroscopy are presented, and laser field fluctuations and the effects of field quantization are dealt with. It gives detailed derivations so the reader can work out all results. References are collected in separate

  10. Generation of Core/shell Nanoparticles with Laser Ablation 

    E-print Network

    Jo, Young Kyong

    2012-10-19

    Two types of core/shell nanoparticles (CS-NPs) generation based on laser ablation are developed in this study, namely, double pulse laser ablation and laser ablation in colloidal solutions. In addition to the study of the generation mechanism of CS...

  11. Generation of Core/shell Nanoparticles with Laser Ablation

    E-print Network

    Jo, Young Kyong

    2012-10-19

    Two types of core/shell nanoparticles (CS-NPs) generation based on laser ablation are developed in this study, namely, double pulse laser ablation and laser ablation in colloidal solutions. In addition to the study of the generation mechanism of CS...

  12. Laser ablation studies in southern Africa

    NASA Astrophysics Data System (ADS)

    McKenzie, Edric; Forbes, A.; Turner, G. R.; Michaelis, Max M.

    2000-08-01

    With the launch of the South African National Laser Centre, new programs will need to be defined. Medical, environmental and industrial laser applications must obviously take top priority -- as opposed to the uranium isotope separation and military applications of the past. We argue however, that a small effort in laser ablation for space propulsion is justifiable, since a few very large CO2 lasers are available and since two tentative propulsion experiments have already been conducted in South Africa. We attempt to give LISP (Laser Impulse Space Propulsion) an equatorial and a Southern dimension.

  13. Laser Ablation for Small Hepatocellular Carcinoma

    PubMed Central

    Pacella, Claudio Maurizio; Francica, Giampiero; Di Costanzo, Giovanni Giuseppe

    2011-01-01

    Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and is increasingly detected at small size (<5?cm) owing to surveillance programmes in high-risk patients. For these cases, curative therapies such as resection, liver transplantation, or percutaneous ablation have been proposed. When surgical options are precluded, image-guided tumor ablation is recommended as the most appropriate therapeutic choice in terms of tumor local control, safety, and improvement in survival. Laser ablation (LA) represents one of currently available loco-ablative techniques: light is delivered via flexible quartz fibers of diameter from 300 to 600??m inserted into tumor lesion through either fine needles (21g Chiba needles) or large-bore catheters. The thermal destruction of tissue is achieved through conversion of absorbed light (usually infrared) into heat. A range of different imaging modalities have been used to guide percutaneous laser ablation, but ultrasound and magnetic resonance imaging are most widely employed, according to local experience and resource availability. Available clinical data suggest that LA is highly effective in terms of tumoricidal capability with an excellent safety profile; the best results in terms of long-term survival are obtained in early HCC so that LA can be proposed not only in unresectable cases but, not differently from radiofrequency ablation, also as the first-line treatment. PMID:22191028

  14. Raman spectroscopy and magnetoelectric properties of laser ablated La and Cr doped BiFeO3 thin films

    Microsoft Academic Search

    R. Palai; R. M. Valdes; S. P. Pavunny; R. S. Katiyar

    2008-01-01

    Epitaxial thin films of multiferroics Bi1-xLaxO3 (x = 0.0, 0.05, 0.10, 0.15 and 0.20)and BiFe1-xCrxO3.....(x = 0.05, 0.10, 0.15 and 0.20) were grown on SrTiO3(100) and (110) substrates by pulsed laser deposition (PLD). X-ray diffraction (XRD)?? was used to study the structure, orientation, and crystallinity of the film. The growth mechanism and microstructure of the films were studied using atomic

  15. Time-resolved diagnostics of excimer laser-generated ablation plasmas used for pulsed laser deposition

    SciTech Connect

    Geohegan, D.B.

    1994-09-01

    Characteristics of laser plasmas used for pulsed laser deposition (PLD) of thin films are examined with four in situ diagnostic techniques: Optical emission spectroscopy, optical absorption spectroscopy, ion probe studies, and gated ICCD (intensified charge-coupled-device array) fast photography. These four techniques are complementary and permit simultaneous views of the transport of ions, excited states, ground state neutrals and ions, and hot particulates following KrF laser ablation of YBCO, BN, graphite and Si in vacuum and background gases. The implementation and advantages of the four techniques are first described in order to introduce the key features of laser plasmas for pulsed laser deposition. Aspects of the interaction of the ablation plume with background gases (i.e., thermalization, attenuation, shock formation) and the collision of the plasma plume with the substrate heater are then summarized. The techniques of fast ICCD photography and gated photon counting are then applied to investigate the temperature, velocity, and spatial distribution of hot particles generated during KrF ablation of YBCO, BN, Si and graphite. Finally, key features of fast imaging of the laser ablation of graphite into high pressure rare gases are presented in order to elucidate internal reflected shocks within the plume, redeposition of material on a surface, and formation of hot nanoparticles within the plume.

  16. Surface properties of femtosecond laser ablated PMMA.

    PubMed

    Marco, Carmela De; Eaton, Shane M; Suriano, Raffaella; Turri, Stefano; Levi, Marinella; Ramponi, Roberta; Cerullo, Giulio; Osellame, Roberto

    2010-08-01

    The effects of femtosecond laser ablation on the physical and chemical properties at the surface of poly methylmethacrylate (PMMA) were studied. Femtosecond laser microfabrication caused the initially wetting behavior of PMMA to become nonwetting, mainly because of the laser-induced surface porosity at the submicroscale. Static and dynamic contact angle measurements along with morphological characterization revealed that after the laser irradiation, the system lies in an intermediate regime between those theorized by Wenzel and Cassie-Baxter. Spectroscopic analysis did not evidence any significant variation in the chemical properties of the processed polymeric surfaces. PMID:20735111

  17. Nanoparticle Formation by Femtosecond Laser Ablation

    Microsoft Academic Search

    Chantal Boulmer-Leborgne; Ratiba Benzerga; Jacques Perrière

    Ultra short femtosecond (fs) pulses for the laser ablation of materials lead to deposited films which are very different from\\u000a those obtained by the well-known classical nanosecond (ns) pulsed laser deposition (PLD). In very specific cases, epitaxial\\u000a thin films can be obtained, whereas in the majority of materials, the films formed by fs PLD are constituted by the random\\u000a stacking

  18. Development and fundamental investigation of Laser Ablation Glow Discharge Time-Of-Flight Mass Spectrometry (LA-GD-TOFMS)

    Microsoft Academic Search

    Mohamed Tarik; Giovanni Lotito; James A. Whitby; Joachim Koch; Katrin Fuhrer; Marc Gonin; Johann Michler; Jean-Luc Bolli; Detlef Günther

    2009-01-01

    Glow Discharge (GD) spectroscopy is a well known and accepted technique for the bulk and surface composition analysis, while laser ablation (LA) provides analysis with high spatial-resolution analysis in LIBS (laser-induced breakdown spectroscopy) or when coupled to inductively coupled plasma spectrometry (ICP-OES or ICP-MS). This work concerns the construction of a Laser Ablation Glow Discharge Time-Of-Flight Mass Spectrometry (LA-GD-TOFMS) instrument

  19. A Review of Laser Ablation Propulsion

    NASA Astrophysics Data System (ADS)

    Phipps, Claude; Bohn, Willy; Lippert, Thomas; Sasoh, Akihiro; Schall, Wolfgang; Sinko, John

    2010-10-01

    Laser Ablation Propulsion is a broad field with a wide range of applications. We review the 30-year history of laser ablation propulsion from the transition from earlier pure photon propulsion concepts of Oberth and Sänger through Kantrowitz's original laser ablation propulsion idea to the development of air-breathing "Lightcraft" and advanced spacecraft propulsion engines. The polymers POM and GAP have played an important rôle in experiments and liquid ablation fuels show great promise. Some applications use a laser system which is distant from the propelled object, for example, on another spacecraft, the Earth or a planet. Others use a laser that is part of the spacecraft propulsion system on the spacecraft. Propulsion is produced when an intense laser beam strikes a condensed matter surface and produces a vapor or plasma jet. The advantages of this idea are that exhaust velocity of the propulsion engine covers a broader range than is available from chemistry, that it can be varied to meet the instantaneous demands of the particular mission, and that practical realizations give lower mass and greater simplicity for a payload delivery system. We review the underlying theory, buttressed by extensive experimental data. The primary problem in laser space propulsion theory has been the absence of a way to predict thrust and specific impulse over the transition from the vapor to the plasma regimes. We briefly discuss a method for combining two new vapor regime treatments with plasma regime theory, giving a smooth transition from one regime to the other. We conclude with a section on future directions.

  20. A Review of Laser Ablation Propulsion

    SciTech Connect

    Phipps, Claude [Photonic Associates, LLC, 200A Ojo de la Vaca Road, Santa Fe NM 87508 (United States); Bohn, Willy [Bohn Laser Consult, Weinberg Weg 43, Stuttgart (Germany); Lippert, Thomas [Paul Scherrer Institut, CH5232 Villigen PSI (Switzerland); Sasoh, Akihiro [Department of Aerospace Engineering, Nagoya University, Chikusa-ku, Nagoya (Japan); Schall, Wolfgang [DLR Institute of Technical Physics, Stuttgart (Germany); Sinko, John [Micro-Nano GCOE, Nagoya University, Furo-cho, Nagoya, Aichi (Japan)

    2010-10-08

    Laser Ablation Propulsion is a broad field with a wide range of applications. We review the 30-year history of laser ablation propulsion from the transition from earlier pure photon propulsion concepts of Oberth and Saenger through Kantrowitz's original laser ablation propulsion idea to the development of air-breathing 'Lightcraft' and advanced spacecraft propulsion engines. The polymers POM and GAP have played an important role in experiments and liquid ablation fuels show great promise. Some applications use a laser system which is distant from the propelled object, for example, on another spacecraft, the Earth or a planet. Others use a laser that is part of the spacecraft propulsion system on the spacecraft. Propulsion is produced when an intense laser beam strikes a condensed matter surface and produces a vapor or plasma jet. The advantages of this idea are that exhaust velocity of the propulsion engine covers a broader range than is available from chemistry, that it can be varied to meet the instantaneous demands of the particular mission, and that practical realizations give lower mass and greater simplicity for a payload delivery system. We review the underlying theory, buttressed by extensive experimental data. The primary problem in laser space propulsion theory has been the absence of a way to predict thrust and specific impulse over the transition from the vapor to the plasma regimes. We briefly discuss a method for combining two new vapor regime treatments with plasma regime theory, giving a smooth transition from one regime to the other. We conclude with a section on future directions.

  1. Surface Characterization of Laser-Ablated Polymers Used for Microfluidics

    Microsoft Academic Search

    D. L. Pugmire; E. A. Waddell; R. Haasch; M. J. Tarlov; L. E. Locascio

    2002-01-01

    Fabrication of microfluidic devices by excimer laser ablation under different atmospheres may provide varia- tions in polymer microchannel surface characteristics. The surface chemistry and electroosmotic (EO) mobility of polymer microchannels laser ablated under different atmospheres were studied by X-ray photoelectron spec- troscopy and current monitoring mobility measurements, respectively. The ablated surfaces of PMMA were very similar to the native material,

  2. Experimental studies on plasma emission spectroscopy of laser ablation of hexahydro-l,3,5-trinitro-l,3,5-triazine

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Shen, Ruiqi; Wu, Lizhi; Ye, Yinghua; Hu, Yan

    2013-05-01

    A Q-switched Nd: YAG laser (with a wavelength of 532 nm and a pulse width of 15 ns) was used to ablate hexahydrol, 3,5-trinitro-l,3,5-triazine (RDX) in the air. The plasma emission spectra were recorded by an intensified charge-coupled device (ICCD) camera. The results showed that the plasma existed in the process of laser ablation of RDX. In the ultraviolet area, the main spectral lines were C I (187.46 nm and 223.01 nm), C II (323.1 nm) and N II (243.72 nm and 332.9 nm), while the dominating emission lines in the visible area were N II (393.9 nm and 454.7 nm), O II (490.75 nm) and O III (401.2 nm). Under experimental conditions, the intensities of the main peaks grew obviously with the increasing of the pulse delay, but laser energy didn't have so much effect on the spectra. The ionization of the air almost did not influence plasma emission lines of RDX.

  3. Ultrafast femtosecond laser ablation of graphite

    NASA Astrophysics Data System (ADS)

    Ionin, Andrey A.; Kudryashov, Sergey I.; Makarov, Sergey V.; Mel’nik, N. N.; Saltuganov, Pavel N.; Seleznev, Leonid V.; Sinitsyn, Dmitry V.

    2015-06-01

    Fluence dependences of IR and UV reflectivity of femtosecond laser pulses on a HOPG surface demonstrate their saturation in a certain fluence range, starting from 0.2?J?cm?2, where single-shot non-linear plasma emission is detected by electric probe measurements. This correlation between prompt solid-state optical/electronic dynamics and electron–ion plasma emission indicates prompt ‘freezing’ of surface electronic dynamics via its plasma-emission cooling and simultaneous ultrafast shallow laser ablation of the surface. Strong HOPG disordering is observed in Raman spectra for laser fluences, exceeding the plasma emission threshold.

  4. Specific Impulse Definition for Ablative Laser Propulsion

    NASA Technical Reports Server (NTRS)

    Herren, Kenneth A.; Gregory, Don A.

    2004-01-01

    The term "specific impulse" is so ingrained in the field of rocket propulsion that it is unlikely that any fundamental argument would be taken seriously for its removal. It is not an ideal measure but it does give an indication of the amount of mass flow (mass loss/time), as in fuel rate, required to produce a measured thrust over some time period This investigation explores the implications of being able to accurately measure the ablation rate and how the language used to describe the specific impulse results may have to change slightly, and recasts the specific impulse as something that is not a time average. It is not currently possible to measure the ablation rate accurately in real time so it is generally just assumed that a constant amount of material will be removed for each laser pulse delivered The specific impulse dependence on the ablation rate is determined here as a correction to the classical textbook definition.

  5. [Laser ablation. Do we still need it?].

    PubMed

    Rosenberg, C; Hoffmann, C O M; Mensel, B; Puls, R; Hosten, N

    2012-01-01

    Laser ablation (LA) is momentarily the only invasive ablation procedure besides radiofrequency ablation (RFA) which can be performed entirely under magnetic resonance imaging (MRI) guidance. The long-term outcome and morbidity profiles are broadly identical for both modalities, excluding the RFA-specific prevalence for skin burns. The technical and logistic disadvantages of LA have been overcome since the introduction of miniaturized two-component applicators. The main advantage of LA is its superior MRI compatibility. Interference-free imaging during LA allows MR thermometric real-time therapy control without the need for RF filters. High-resolution thermometry in the target zone only makes sense without the extinction artifact of a metal probe and this condition is met only by the glass fibers of LA. An independent therapy monitoring is crucial in modern scenarios of oncologic quality management. PMID:22249697

  6. Subcellular analysis by laser ablation electrospray ionization mass spectrometry

    DOEpatents

    Vertes, Akos; Stolee, Jessica A; Shrestha, Bindesh

    2014-12-02

    In various embodiments, a method of laser ablation electrospray ionization mass spectrometry (LAESI-MS) may generally comprise micro-dissecting a cell comprising at least one of a cell wall and a cell membrane to expose at least one subcellular component therein, ablating the at least one subcellular component by an infrared laser pulse to form an ablation plume, intercepting the ablation plume by an electrospray plume to form ions, and detecting the ions by mass spectrometry.

  7. Nanosecond Infrared Laser for Tissue Ablation

    NASA Astrophysics Data System (ADS)

    Edwards, G. S.; Pearlstein, R. D.; Copeland, M. L.; Hutson, M. S.; Latone, K.; Spiro, A.; Pasmanik, G.

    2007-03-01

    The Mark-III Free-Electron Laser (FEL), operating at the 6.45?m wavelength, has been used successfully in human surgery. Due to the FEL's size and cost, there has been interest in the development of a compact, inexpensive infrared laser for human surgical applications. We have investigated the role of the FEL superpulse, leading to the prediction that nanosecond pulses can satisfy the dynamic criteria for tissue ablation. We have developed a laser based on difference frequency mixing and stimulated Raman scattering with four stages of frequency conversion, emitting at a wavelength of 6.45?m with 3-5ns pulse duration, pulse energies of up to 2mJ, and a pulse repetition rate of 3MHz. The laser system successfully ablated tissue, where collateral thermal damage was limited to several microns. In the future, it will be necessary to increase the pulse repetition rate to achieve an ablation rate acceptable for human surgery. We acknowledge the grant support: R43 RR018435, N00014-99-1-0891, and F49620-00-1-0370.

  8. Status of the Ablative Laser Propulsion Studies

    NASA Technical Reports Server (NTRS)

    Herren, Kenneth A.; Lin, Jun; Cohen, Tinothy; Pakhomov, Andrew V.; Thompson, M. Shane

    2004-01-01

    We present a short review of our laser-propulsion research as well as some of the current results of the Ablative Laser Propulsion (ALP) studies currently underway at the University of Alabama in Huntsville. It has been shown that direct surface ablation of a solid material produces high specific impulse (Isp) at relatively high energy conversion efficiency (20 - 40%). We detail measurements of specific impulse, thrust and coupling coefficients for elemental target materials both with single and with double pulse laser shots. We also present measurements taken using three independent methods for determination of Isp. The three methods produce consistent values from ion time-of-flight technique, impulse measurements and imaging of the expansion front of plasma plume. We present a demonstration of our ALP lightcraft, a small free-flying micro-vehicle that is propelled by ablation. For ALP lightcraft we use a subscale thin shell of nickel replicated over a diamond turned mandrel that produces a highly polished self-focusing, truncated at the focus parabolic mirror. The mass of the lightcraft is 54 mg and it is driven by 100-ps wide, 35-mJ laser pulses at 532 nm wavelength. This is an ongoing research. We also present the latest work on laserdriven micro-thrusters and detail some the near term goals of our program.

  9. Modeling CO{sub 2} Laser Ablative Impulse with Polymers

    SciTech Connect

    Sinko, John E. [Micro-Nano Global Center of Excellence (GCOE), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan 464-8603 (Japan); Phipps, Claude R. [Photonic Associates, LLC, 200A Ojo de la Vaca Rd., Santa Fe, NM 87508 (United States); Sasoh, Akihiro [Department of Aerospace Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan, 464-8603 (Japan)

    2010-10-08

    Laser ablation vaporization models have usually ignored the spatial dependence of the laser beam. Here, we consider effects from modeling using a Gaussian beam for both photochemical and photothermal conditions. The modeling results are compared to experimental and literature data for CO{sub 2} laser ablation of the polymer polyoxymethylene under vacuum, and discussed in terms of the ablated mass areal density and momentum coupling coefficient. Extending the scope of discussion, laser ablative impulse generation research has lacked a cohesive strategy for linking the vaporization and plasma regimes. Existing models, mostly formulated for ultraviolet laser systems or metal targets, appear to be inappropriate or impractical for applications requiring CO{sub 2} laser ablation of polymers. A recently proposed method for linking the vaporization and plasma regimes for analytical modeling is addressed here along with the implications of its use. Key control parameters are considered, along with the major propulsion parameters needed for laser ablation propulsion modeling.

  10. A novel method for the identification of inorganic and organic gunshot residue particles of lead-free ammunitions from the hands of shooters using scanning laser ablation-ICPMS and Raman micro-spectroscopy.

    PubMed

    Abrego, Zuriñe; Grijalba, Nagore; Unceta, Nora; Maguregui, Maite; Sanchez, Alicia; Fernández-Isla, Alberto; Goicolea, M Aranzazu; Barrio, Ramón J

    2014-12-01

    A method based on scanning laser ablation and inductively coupled plasma-mass spectrometry (SLA-ICPMS) and Raman micro-spectroscopy for the detection and identification of compounds consistent with gunshot residue particles (GSR) has been developed. The method has been applied to the characterization of particles resulting from the discharge of firearms using lead-free ammunition. Modified tape lifts were used to collect the inorganic and organic residues from skin surfaces in a single sample. Using SLA-ICPMS, aggregates related to the composition of the ammunition, such as Cu-Zn-Sn, Zr-Sr, Cu-Zn, Al-Ti, or Al-Sr-Zr were detected, but this composition is only consistent with GSR from lead-free ammunitions. Additional evidence was provided by micro-Raman spectroscopy, which identified the characteristic organic groups of the particles as centralite, diphenylamine or their nitrated derivatives, which are indicative of GSR. PMID:25303642

  11. Deposition of Er 3+ doped chalcogenide glass films by excimer laser ablation

    Microsoft Academic Search

    E. N. Borisov; V. B. Smirnov; A. Tverjanovich; Yu. S. Tveryanovich

    2003-01-01

    The Ga2S3–GeS2:Er2S3 films of various thicknesses (from 0.3 to 5 ?m) were prepared by laser ablation. The deposed films were characterized with various diagnostic techniques: optical absorption spectroscopy, X-ray fluorescence spectroscopy, secondary ion mass spectroscopy and luminescence spectroscopy. Concentrations of rare-earth ions, gallium and germanium in the target bulk glass and in the films were similar. The composition of deposited

  12. Nanochemical effects in femtosecond laser ablation of metals

    SciTech Connect

    Vorobyev, A. Y.; Guo, Chunlei [The Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)] [The Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)

    2013-02-18

    We study chemical energy released from the oxidation of aluminum in multipulse femtosecond laser ablation in air and oxygen. Our study shows that the released chemical energy amounts to about 13% of the incident laser energy, and about 50% of the ablated material is oxidized. The ablated material mass per laser pulse is measured to be on the nanogram scale. Our study indicates that femtosecond laser ablation is capable of inducing nanochemical reactions since the femtosecond laser pulse can controllably produce nanoparticles, clusters, and atoms from a solid target.

  13. PZT thin films grown by laser ablation

    Microsoft Academic Search

    Tupac Garcia; E. de Posada; Ernesto Jimenez; F. Calderon; P. Bartolo-Perez; J. L. Pena

    1999-01-01

    PZT thin films were deposited by laser ablation at high vacuum and at room temperature. After that, some of the samples were annealed at air in the temperature range 450 degree(s)C - 550 degree(s)C. The samples were characterized by XPS and X-ray diffraction. A decrease in the oxygen composition of the as-deposited sample was observed. In the as-deposited film metallic

  14. Laser concrete ablation scaling effects

    Microsoft Academic Search

    Danny ONeill MacCallum; Jerome T. Norris

    2008-01-01

    Surface scabbling of concrete by laser processing has been demonstrated in the literature for large-area problems (50 mm wide x 10 deep) using physically large, high-power consumption, multi-kW CW laser systems. With large spot diameters (50 mm) and low power densities ( 300 W\\/cm²), large volume thermal stresses are induced which promote concrete cracking. This process is highly power-density and

  15. Solar cell contact formation using laser ablation

    DOEpatents

    Harley, Gabriel; Smith, David D.; Cousins, Peter John

    2014-07-22

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline materiat layer; and forming conductive contacts in the plurality of contact holes.

  16. Solar cell contact formation using laser ablation

    DOEpatents

    Harley, Gabriel; Smith, David; Cousins, Peter

    2012-12-04

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  17. CO2 Laser Absorption in Ablation Plasmas

    SciTech Connect

    Eckel, Hans-Albert; Tegel, Jochen; Schall, Wolfgang O. [DLR-Institute of Technical Physics, D-70503 Stuttgart, Postfach 80 03 20 (Germany)

    2006-05-02

    The impulse formation by laser ablation is limited by the premature absorption of the incident laser radiation in the initially produced cloud of ablation products. The power fraction of a CO2 laser pulse transmitted through a small hole in a POM sample for pulse energies of 35 to 150 J focused on a spot of 2 cm2 has been compared with the incident power. The plasma formation in vacuum and in air of 3500 Pa and the spread of the shock wave with velocities of 1.6 to 2.4 km/s in the low pressure air was observed by Schlieren photography. A sharp edged dark zone with a maximum extension of 10 to 12 mm away from the target surface develops within 5 {mu}s independently of the pressure and is assumed to be a plasma. In order to find out, if this is also the zone where the majority of the incident laser radiation is absorbed, a CO2 probe laser beam was directed through the expansion cloud parallel to and at various distances from the sample surface. The time behavior of the absorption signal of the probe beam has been measured and an absorption wave could be observed.

  18. Laser-Induced Breakdown Spectroscopy---Capabilities and Limitations

    Microsoft Academic Search

    David A. Cremers; Rosemarie C. Chinni

    2009-01-01

    During the past decade there has been intense activity in the field of laser-induced breakdown spectroscopy (LIBS). This activity includes studies of laser ablation and properties of the laser spark, the development of methods to enhance LIBS detection capabilities, and the application of LIBS to specific analysis needs. The unique capabilities of LIBS make it particularly suited for applications that

  19. Laser ablation atmospheric pressure photoionization mass spectrometry imaging of phytochemicals from sage leaves

    E-print Network

    Vertes, Akos

    Laser ablation atmospheric pressure photoionization mass spectrometry imaging of phytochemicals. In this contribution, we explore the feasibility of laser ablation atmospheric pressure photoionization (LAAPPI technique, laser ablation atmospheric pressure photoionization (LAAPPI),[12] for MSI. For microsampling

  20. Effects of laser ablation on cemented tungsten carbide surface quality

    NASA Astrophysics Data System (ADS)

    Tan, J. L.; Butler, D. L.; Sim, L. M.; Jarfors, A. E. W.

    2010-11-01

    Although laser micromachining has been touted as being the most promising way to fabricate micro tools, there has been no proper evaluation of the effects of laser ablation on bulk material properties. The current work demonstrates the effects of laser ablation on the properties of a cemented tungsten carbide surface. Of particular interest is the resultant increase in compressive residual stresses in the ablated surface. From this study it is seen that there are no adverse effects from laser ablation of cemented tungsten carbide that would preclude its use for the fabrication of micro-tools but a finishing process may not be avoidable.

  1. Preparation of nanofluids using laser ablation in liquid technique

    SciTech Connect

    Tran, P.X.; Soong, Yee

    2007-06-01

    In this work we report some results on thermal and transport properties of Ag-di water and Al-di water nanofluids that were prepared using Nd:yag laser to ablate Ag and Al in deionized water. The produced nanofluids were characterized using UV-VIS spectroscopy and TEM analysis. Our results on the UV-VIS spectra of the generated nanofluids demonstrated that using laser ablation in liquid we could generate stable colloids containing well-dispersed nanosized particles without use of any dispersants or surface reactive reagents. For Ag-di water nanofluids, the particles were spherical and the majority of the particles were in the 9 – 21 nm range with some big ones 23 - 26nm in size. The results on Al showed that the amplitude of the UV-VIS absorption spectra of Al-di water changed with time indicating that the ablated Al species reacts with water to yield an amorphous gel that transforms to the crystallized aluminum hydroxides with different shapes and sizes. The shapes were fibrous, triangular, rectangular, spherical shapes and joining of two pieces of triangles. In fact, these triangular and rectangular shapes were indeed pyramidal structures and hexagonal prisms, respectively.

  2. Subsurface ablation of atherosclerotic plaque using ultrafast laser pulses

    PubMed Central

    Lanvin, Thomas; Conkey, Donald B.; Frobert, Aurelien; Valentin, Jeremy; Goy, Jean-Jacques; Cook, Stéphane; Giraud, Marie-Noelle; Psaltis, Demetri

    2015-01-01

    We perform subsurface ablation of atherosclerotic plaque using ultrafast pulses. Excised mouse aortas containing atherosclerotic plaque were ablated with ultrafast near-infrared (NIR) laser pulses. Optical coherence tomography (OCT) was used to observe the ablation result, while the physical damage was inspected in histological sections. We characterize the effects of incident pulse energy on surface damage, ablation hole size, and filament propagation. We find that it is possible to ablate plaque just below the surface without causing surface damage, which motivates further investigation of ultrafast ablation for subsurface atherosclerotic plaque removal.

  3. Nanosecond laser ablation for pulsed laser deposition of yttria

    NASA Astrophysics Data System (ADS)

    Sinha, Sucharita

    2013-09-01

    A thermal model to describe high-power nanosecond pulsed laser ablation of yttria (Y2O3) has been developed. This model simulates ablation of material occurring primarily through vaporization and also accounts for attenuation of the incident laser beam in the evolving vapor plume. Theoretical estimates of process features such as time evolution of target temperature distribution, melt depth and ablation rate and their dependence on laser parameters particularly for laser fluences in the range of 6 to 30 J/cm2 are investigated. Calculated maximum surface temperatures when compared with the estimated critical temperature for yttria indicate absence of explosive boiling at typical laser fluxes of 10 to 30 J/cm2. Material ejection in large fragments associated with explosive boiling of the target needs to be avoided when depositing thin films via the pulsed laser deposition (PLD) technique as it leads to coatings with high residual porosity and poor compaction restricting the protective quality of such corrosion-resistant yttria coatings. Our model calculations facilitate proper selection of laser parameters to be employed for deposition of PLD yttria corrosion-resistive coatings. Such coatings have been found to be highly effective in handling and containment of liquid uranium.

  4. Dynamics of excimer laser ablation of superconductors in an oxygen environment

    SciTech Connect

    Dyer, P.E.; Issa, A.; Key, P.H. (Department of Applied Physics, University of Hull, Hull, HU6 7RX (United Kingdom))

    1990-07-09

    The plume dynamics for excimer laser ablation of Y-Ba-Cu-O in an O{sub 2} atmosphere have been studied using streak photography and spectroscopy. At pressures {approx gt}1 mbar the expansion resembles a blast wave driven by the ablation products with mixing and reaction at the contact surface. A simple model for the plume range is developed which shows agreement with experiments.

  5. Pulsed holmium laser ablation of cardiac valves

    SciTech Connect

    Lilge, L.; Radtke, W.; Nishioka, N.S. (Massachusetts General Hospital, Boston (USA))

    1989-01-01

    Ablation efficiency and residual thermal damage produced by pulsed holmium laser radiation were investigated in vitro for bovine mitral valves and human calcified and noncalcified cardiac valves. Low-OH quartz fibers (200 and 600 microns core diameter) were used in direct contact perpendicular to the specimen under saline or blood. Etch rate was measured with a linear motion transducer. Radiant exposure was varied from 0 to 3 kJ/cm{sup 2}. For 200-microns fibers, the energy of ablation was approximately 5 kJ/cm{sup 3} in noncalcified and 15 kJ/cm{sup 3} in calcified valves. Etch rates were dependent on mechanical tissue properties. Maximum etch rate at 1,000 J/cm{sup 2} was 1-2 mm/pulse at 3 Hz repetition rate. Microscopic examination revealed a zone of thermal damage extending 300 microns lateral into adjacent tissue. Thermal damage was independent of radiant exposure beyond twice threshold.

  6. Dynamics of laser ablation of biological tissues

    NASA Astrophysics Data System (ADS)

    Bor, Z.; Szabó, G.; Hopp, B.; Márton, Zs.; Juhász, T.

    1993-10-01

    We have developed a subnanosecond time resolution ultrafast photographic setup that can be used both as shadowgraph and Schlieren apparatus. With this setup a detailed study of the time history of the plume ejection and shock wave propagation have been preformed. We have shown that the shock wave fronts follow the behaviour predicted by shock wave theories, and that the planar shock wave fronts travel always perpendicular to the ablated surface. In addition to the earlier known hemispherical shock wave a new, head-wave type wave front was found that is presumably caused by a bunch of very fast particles preceding the formation of the main ablation plume. We have shown that the dynamics of short pulse Nd laser induced cavitation bubbles is considerably different in water and bovine cornea.

  7. Ultrashort-pulse laser ablation of indium phosphide in air

    Microsoft Academic Search

    J. Bonse; J. M. Wrobel; J. Krüger; W. Kautek

    2001-01-01

    .   Ablation of indium phosphide wafers in air was performed with low repetition rate ultrashort laser pulses (130 fs, 10 Hz)\\u000a of 800 nm wavelength. The relationships between the dimensions of the craters and the ablation parameters were analyzed. The\\u000a ablation threshold fluence depends on the number of pulses applied to the same spot. The single-pulse ablation threshold value\\u000a was estimated to be

  8. Thermal Ablation for Benign Thyroid Nodules: Radiofrequency and Laser

    PubMed Central

    Lee, Jeong Hyun; Valcavi, Roberto; Pacella, Claudio M.; Rhim, Hyunchul; Na, Dong Gyu

    2011-01-01

    Although ethanol ablation has been successfully used to treat cystic thyroid nodules, this procedure is less effective when the thyroid nodules are solid. Radiofrequency (RF) ablation, a newer procedure used to treat malignant liver tumors, has been valuable in the treatment of benign thyroid nodules regardless of the extent of the solid component. This article reviews the basic physics, techniques, applications, results, and complications of thyroid RF ablation, in comparison to laser ablation. PMID:21927553

  9. Effect of ambient air on femtosecond laser ablation of highly oriented pyrolytic graphite.

    PubMed

    Feng, Peipei; Zhang, Nan; Wu, Han; Zhu, Xiaonong

    2015-01-01

    Highly oriented pyrolytic graphite is ablated by femtosecond laser in air and vacuum, respectively. The morphologies and material components of the ablated target surface are examined by scanning electron microscopy and micro-Raman spectroscopy. For laser fluence no less than 0.5??J/cm(2), the laser-induced periodic surface grooves formed in air are found to be much less clearer than those formed in vacuum; beneath the amorphous carbon debris, the surface ablated in air is composed of nanocrystalline graphite, but in vacuum it retains the ordered graphite structure. The thermal relaxation of the ablated target induced by air-assisted heat transfer is considered to be the main reason for the differences. The transportation of air molecules along the surface, the classical size effect of heat conduction and high solid-air heat transfer coefficient in nanoscale enhance the air-assisted heat transfer. PMID:25531597

  10. Laser-induced breakdown spectroscopy in a biological tissue

    Microsoft Academic Search

    Hanriete P. de Souza; Egberto Munin; Leandro P. Alves; Marcela L. Redígolo; Marcos Tadeu; T. Pacheco

    2003-01-01

    The relative atomic composition of the laser-generated ablation plume in chicken myocardium is investigated by using luminescence spectroscopy. A Q-switched Nd:YAG laser emitting at 1064 nm with 9 ns pulse duration was used for the tissue ablation. The selected ou tput energy was 210 mJ and the beam was focused to a 0.8 mm diameter spot size by using a

  11. Elemental fractionation of glass using laser ablation inductively coupled plasma mass spectrometry

    SciTech Connect

    Figg, D. [CST-9, Chemical Science and Technology Division, Los Alamos National Laboratory, Los Alamos New Mexico, 87545 (United States)] [CST-9, Chemical Science and Technology Division, Los Alamos National Laboratory, Los Alamos New Mexico, 87545 (United States); Kahr, M.S. [CST-9, Chemical Science and Technology Division, Los Alamos National Laboratory, Los Alamos New Mexico, 87545 (United States)] [CST-9, Chemical Science and Technology Division, Los Alamos National Laboratory, Los Alamos New Mexico, 87545 (United States); [Orbital Sciences Corporation, 2771 North Garey Ave., Pomona, California 91767 (United States)

    1997-08-01

    Three laser wavelengths (1064, 532, and 266 nm) were employed for laser ablation at varied laser pulse energies to study the effect of irradiance and wavelength upon analytical results for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Two important results were observed and are reported here: (1) the intensity of the MS signal came to a local minimum when the laser focal point was on the sample surface, and (2) elemental fractionation based upon laser wavelength and laser pulse energy was observed. For the waste glass simulant studied, ablation with 1064-nm (IR) and 532-nm (green) radiation produced elemental fractionation that relates to the melting point of the elemental oxide, whereas with 266-nm (UV) ablation the response was independent of the elemental oxide melting point. At high laser powers, ablation at 266 nm produced an elemental bias based upon the mass of the elements. These observations suggest the use of ultraviolet radiation at low pulse energies to obtain improved analytical results. {copyright} {ital 1997} {ital Society for Applied Spectroscopy}

  12. RESEARCH Open Access Focal Laser Ablation of Prostate Cancer

    E-print Network

    Paris-Sud XI, Université de

    RESEARCH Open Access Focal Laser Ablation of Prostate Cancer: Numerical Simulation of Temperature between simulation and in vivo experiments of FLA for prostate cancer. Simulation is a promising planning surgical method. Keywords: Prostate cancer focal laser ablation, thermal damage, bioheat transfer

  13. Laser Ablation Synthesis and Optical Characterization of Silicon Carbide Nanowires

    E-print Network

    Zheng, Yufeng

    Laser Ablation Synthesis and Optical Characterization of Silicon Carbide Nanowires Wensheng Shi Kong, SAR, China Silicon carbide (SiC) nanowires were synthesized at 900°C by the laser ablation technique. The growth morphology, micro- structure, and defects in SiC nanowires were characterized

  14. ABLATION AND MICROMACHINING OF INP WITH FEMTOSECOND LASER PULSES

    Microsoft Academic Search

    Andrzej Borowiec

    2004-01-01

    This thesis details the results of femtosecond laser ablation and micromachining of indium phosphide (InP). The experimental results presented consist of six sets of investigations divided into two categories: I) single and multiple pulse ablation of stationary samples; 2) laser micromachining and analysis of grooves cut in InP. The first series of experiments dealt with the analysis of the final

  15. Evidence of an implantation process in carbon deposition on Si(100) at high substrate temperature by laser ablation

    Microsoft Academic Search

    J. A. Martín-Gago; F. Comin; S. Ferrer

    1996-01-01

    The growth mode of carbon atoms on a clean and reconstructed Si(100) surface using the laser ablation deposition technique, with the substrate held at high temperature (?500°C) during deposition, has been investigated by means of low energy ion scattering spectroscopy (ISS), Auger electron spectroscopy (AES), electron energy loss spectroscopy (EELS) and scanning tunneling microscopy (STM). In contrast with the room

  16. Laser Surgery: Alternatives To CO2 Ablation

    NASA Astrophysics Data System (ADS)

    Wolbarsht, Myron L.

    1985-11-01

    Laser surgery may be improved by modifications based on similar processes in industrial applications. A major problem in materials processing is minimizing heat diffusion from the site of laser exposure. The same problem exists in tne surgery of tissue with a CO2 laser. A model is described which indicates that radiation at 2.9 ?m (HF laser) in short duration pulses, shorter than the thermal relaxation time (1.7 ps) of its 2 um thick absorption depth in water, will minimize thermal diffusion, and also take advantage of the large amount of heat removed by the phase change of water into steam. This model suggests that, for deep cuts, many short pulses are preferable to a single long duration exposure and that more delicate surgery may be possible with such short pulse, shallow absorption depth types of energy delivery. For coagulation (nemostasis control) as well as ablation, two simultaneous wavelengths are required, 2.9 ?m for cutting, and another, with less absorption, (such as 1.06 ?m from Nu:YAG or 466-J14 nm from Argon lasers) for more penetration and heating of upper layers and blood vessels. Among the secondary benefits of the use of the HF laser at 2.9 ?m is ready availability of flexible optical fibers for a delivery system.

  17. Mechanism study of skin tissue ablation by nanosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Fang, Qiyin

    Understanding the fundamental mechanisms in laser tissue ablation is essential to improve clinical laser applications by reducing collateral damage and laser pulse energy requirement. The motive of this dissertation is to study skin tissue ablation by nanosecond laser pulses in a wide spectral region from near-infrared to ultraviolet for a clear understanding of the mechanism that can be used to improve future design of the pulsed lasers for dermatology and plastic surgery. Multiple laser and optical configurations have been constructed to generate 9 to 12ns laser pulses with similar profiles at 1064. 532, 266 and 213nm for this study of skin tissue ablation. Through measurements of ablation depth as a function cf laser pulse energy, the 589nm spectral line in the secondary radiation from ablated skin tissue samples was identified as the signature of the occurrence of ablation. Subsequently, this spectral signature has been used to investigate the probabilistic process of the ablation near the threshold at the four wavelengths. Measurements of the ablation probability were conducted as a function of the electrical field strength of the laser pulse and the ablation thresholds in a wide spectral range from 1064nm to 213nm were determined. Histology analysis and an optical transmission method were applied in assessing of the ablation depth per pulse to study the ablation process at irradiance levels higher than threshold. Because more than 70% of the wet weight of the skin tissue is water, optical breakdown and backscattering in water was also investigated along with a nonlinear refraction index measurement using a z-scan technique. Preliminary studies on ablation of a gelatin based tissue phantom are also reported. The current theoretical models describing ablation of soft tissue ablation by short laser pulses were critically reviewed. Since none of the existing models was found capable of explaining the experimental results, a new plasma-mediated model was developed. A laser-induced and localized thermal ionization pathway has been investigated and it was found to have significant influence on the initial free electron density during plasma formation due to the combination of strong light absorption by chromophores and confined temperature rise in the chromophores. Good agreements have been found between the new plasma-mediated ablation model and experimental results. The implications of this dissertation research to the future improvement of laser systems in dermatology and plastic surgery are discussed.

  18. Laser ablation loading of a surface-electrode ion trap

    E-print Network

    David R. Leibrandt; Robert J. Clark; Jaroslaw Labaziewicz; Paul Antohi; Waseem Bakr; Kenneth R. Brown; Isaac L. Chuang

    2007-06-22

    We demonstrate loading by laser ablation of $^{88}$Sr$^+$ ions into a mm-scale surface-electrode ion trap. The laser used for ablation is a pulsed, frequency-tripled Nd:YAG with pulse energies of 1-10 mJ and durations of 3-5 ns. An additional laser is not required to photoionize the ablated material. The efficiency and lifetime of several candidate materials for the laser ablation target are characterized by measuring the trapped ion fluorescence signal for a number of consecutive loads. Additionally, laser ablation is used to load traps with a trap depth (40 meV) below where electron impact ionization loading is typically successful ($\\gtrsim$ 500 meV).

  19. Femtosecond laser ablation of brass in air and liquid media

    SciTech Connect

    Shaheen, M. E. [Great Lakes Institute for Environmental Research (GLIER), University of Windsor, Windsor, Ontario N9B 3P4 (Canada) [Great Lakes Institute for Environmental Research (GLIER), University of Windsor, Windsor, Ontario N9B 3P4 (Canada); Department of Physics, Faculty of Sciences, Tanta University, Tanta (Egypt); Gagnon, J. E.; Fryer, B. J. [Great Lakes Institute for Environmental Research (GLIER), University of Windsor, Windsor, Ontario N9B 3P4 (Canada) [Great Lakes Institute for Environmental Research (GLIER), University of Windsor, Windsor, Ontario N9B 3P4 (Canada); Department of Earth and Environmental Sciences, University of Windsor, Windsor, Ontario N9B 3P4 (Canada)

    2013-06-07

    Laser ablation of brass in air, water, and ethanol was investigated using a femtosecond laser system operating at a wavelength of 785 nm and a pulse width less than 130 fs. Scanning electron and optical microscopy were used to study the efficiency and quality of laser ablation in the three ablation media at two different ablation modes. With a liquid layer thickness of 3 mm above the target, ablation rate was found to be higher in water and ethanol than in air. Ablation under water and ethanol showed cleaner surfaces and less debris re-deposition compared to ablation in air. In addition to spherical particles that are normally formed from re-solidified molten material, micro-scale particles with varying morphologies were observed scattered in the ablated structures (craters and grooves) when ablation was conducted under water. The presence of such particles indicates the presence of a non-thermal ablation mechanism that becomes more apparent when ablation is conducted under water.

  20. Band-pass filters for THz spectral range fabricated by laser ablation

    NASA Astrophysics Data System (ADS)

    Voisiat, B.; Bi?i?nas, A.; Kašalynas, I.; Ra?iukaitis, G.

    2011-09-01

    The terahertz resonant metal-mesh filters were fabricated using the laser direct writing technique. UV picosecond laser was employed to cut matrixes of cross-shaped holes in stainless steel foil and molybdenum layer deposited on polyimide substrate. Different laser processing strategies were developed: holes were cut through in the metal foil and the molybdenum film was removed from the polyimide by laser ablation. Band-pass filters with a different center frequency were designed and fabricated. The regular shape, smoothness of edges and sharpness of corners of the cross-shaped holes in the metal were the main attributes for quality assessment for the laser ablation process. Spectral characteristics of the filters, determined by the mesh period, cross-arm length, and its width, were investigated by terahertz time-domain spectroscopy and conventional space-domain Fourier transform spectroscopy. Experimental data were supported by three-dimensional finite-difference time-domain simulations.

  1. Laser ablated copper plasmas in liquid and gas ambient

    SciTech Connect

    Kumar, Bhupesh; Thareja, Raj K. [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)] [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)

    2013-05-15

    The dynamics of copper ablated plasma plumes generated using laser ablation of copper targets in both liquid (de-ionized water) and gas (air) ambients is reported. Using time and space resolved visible emission spectroscopy (450-650 nm), the plasma plumes parameters are investigated. The electron density (n{sub e}) determined using Stark broadening of the Cu I (3d{sup 10}4d{sup 1} {sup 2}D{sub 3/2}-3d{sup 10}4p{sup 1} {sup 2}P{sub 3/2} at 521.8 nm) line is estimated and compared for both plasma plumes. The electron temperature (T{sub e}) was estimated using the relative line emission intensities of the neutral copper transitions. Field emission scanning electron microscopy and energy dispersive x-ray spectral analysis of the ablated copper surface indicated abundance of spherical nanoparticles in liquid while those in air are amalgamates of irregular shapes. The nanoparticles suspended in the confining liquid form aggregates and exhibit a surface plasmon resonance at ?590 nm.

  2. Plume collimation for laser ablation electrospray ionization mass spectrometry

    DOEpatents

    Vertes, Akos; Stolee, Jessica A.

    2014-09-09

    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  3. Medieval glass from the Cathedral in Paderborn: a comparative study using X-ray absorption spectroscopy, X-ray fluorescence, and inductively coupled laser ablation mass spectrometry

    NASA Astrophysics Data System (ADS)

    Hormes, J.; Roy, A.; Bovenkamp, G.-L.; Simon, K.; Kim, C.-Y.; Börste, N.; Gai, S.

    2013-04-01

    We have investigated four stained glass samples recovered from an archaeological excavation at the Cathedral in Paderborn (Germany) between 1978 and 1980. On two of the samples there are parts of paintings. Concentrations of major elements were determined using two independent techniques: LA-ICP-MS (a UV laser ablation microsampler combined with an inductively coupled plasma mass spectrometer) and synchrotron radiation X-ray excited X-ray fluorescence (SR-XRF). The SR-XRF data were quantified by using the program package PyMCA developed by the software group of the ESRF in Grenoble. Significant differences were found between the concentrations determined by the two techniques that can be explained by concentration gradients near the surface of the glasses caused, for example, by corrosion/leaching processes and the different surface sensitivities of the applied techniques. For several of the elements that were detected in the glass and in the colour pigments used for the paintings X-ray absorption near edge structure (XANES) spectra were recorded in order to determine the chemical speciation of the elements of interest. As was expected, most elements in the glass were found as oxides in their most stable form. Two notable exceptions were observed: titanium was not found as rutile—the most stable form of TiO2—but in the form of anatase, and lead was not found in one defined chemical state but as a complex mixture of oxide, sulphate, and other compounds.

  4. Elemental bioimaging of nanosilver-coated prostheses using X-ray fluorescence spectroscopy and laser ablation-inductively coupled plasma-mass spectrometry.

    PubMed

    Blaske, Franziska; Reifschneider, Olga; Gosheger, Georg; Wehe, Christoph A; Sperling, Michael; Karst, Uwe; Hauschild, Gregor; Höll, Steffen

    2014-01-01

    The distribution of different chemical elements from a nanosilver-coated bone implant was visualized, combining the benefits of two complementary methods for elemental bioimaging, the nondestructive micro X-ray fluorescence (?-XRF), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Challenges caused by the physically inhomogeneous materials including bone and soft tissues were addressed by polymer embedding. With the use of ?-XRF, fast sample mapping was achieved obtaining titanium and vanadium signals from the metal implant as well as phosphorus and calcium signals representing hard bone tissue and sulfur distribution representing soft tissues. Only by the use of LA-ICP-MS, the required high sensitivity and low detection limits for the determination of silver were obtained. Metal distribution within the part of cancellous bone was revealed for silver as well as for the implant constituents titanium, vanadium, and aluminum. Furthermore, the detection of coinciding high local zirconium and aluminum signals at the implant surface indicates remaining blasting abrasive from preoperative surface treatment of the nanosilver-coated device. PMID:24320121

  5. Optimization of laser ablation and signal enhancement for nuclear material detection

    NASA Astrophysics Data System (ADS)

    LaHaye, Nicole L.

    The purpose of the study was to investigate the role of different laser parameters on laser ablation properties, specifically in terms of performance in laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Many laser parameters affect laser ablation performance, including laser wavelength and pulse duration, as presented here. It was previously thought that wavelength plays no role in ultrafast laser ablation; however, it was found that shorter wavelength yields lower detection limits and ablation threshold. Our results also demonstrate that in the laser pulse duration range of 40 fs to 1 ps, negligible differences occur in signal intensity, elemental ratios, and detection limits. U/Pb and U/Th ratios, which were examined to ensure limited fractionation, give comparable results at all pulse widths investigated. A parametric study of plasma hydrodynamics will also be presented. An elemental detection method combining laser induced breakdown spectroscopy (LIBS) and LA-ICP-MS is developed, with plasma density and temperature actively monitored to investigate how plasma conditions affect ICP-MS results. The combination of these two methods will help to mitigate the disadvantages of using each technique individually. Depth and spatial analysis of thin films was performed using femtosecond LA-ICP-MS to study the stoichiometric distribution of the films. The thin film-substrate interface was probed, revealing intermixing between the two layers. Lastly, the persistence of uranium emission in laser-produced plasmas (LPP) was investigated under various Ar ambient environments. Plasma collisional effects and confinement play a very important role in emission intensity and persistence, yielding important results for future LIBS and laser absorption spectroscopy (LAS) research. Lastly, suggestions for future work are made, which include extension of the LIBS and LA-ICP-MS systems to other samples like oxide thin films and spatial and depth profiling of known heterogeneous materials.

  6. Dynamics of laser ablation plume penetration through low pressure background gases

    E-print Network

    Geohegan, David B.

    with a simple scattering model effective cross sections 1 10 16 cm2 ).2­4,6 Eventually, ion probe and fast. Puretzky Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Russia Received 13 March 1995 . During expansion into low-pressure background gases, the ion flux in the laser ablation plasma plume

  7. Metal particles produced by laser ablation for ICP-MSmeasurements

    SciTech Connect

    Gonzalez, Jhanis J.; Liu, Chunyi; Wen, Sy-Bor; Mao, Xianglei; Russo, Richard E.

    2007-06-01

    Pulsed laser ablation (266nm) was used to generate metal particles of Zn and Al alloys using femtosecond (150 fs) and nanosecond (4 ns) laser pulses with identical fluences of 50 J cm{sup -2}. Characterization of particles and correlation with Inductively Coupled Plasma Mass Spectrometer (ICP-MS) performance was investigated. Particles produced by nanosecond laser ablation were mainly primary particles with irregular shape and hard agglomerates (without internal voids). Particles produced by femtosecond laser ablation consisted of spherical primary particles and soft agglomerates formed from numerous small particles. Examination of the craters by white light interferometric microscopy showed that there is a rim of material surrounding the craters formed after nanosecond laser ablation. The determination of the crater volume by white light interferometric microscopy, considering the rim of material surrounding ablation craters, revealed that the volume ratio (fs/ns) of the craters on the selected samples was approximately 9 (Zn), 7 (NIST627 alloy) and 5 (NIST1711 alloy) times more ablated mass with femtosecond pulsed ablation compared to nanosecond pulsed ablation. In addition, an increase of Al concentration from 0 to 5% in Zn base alloys caused a large increase in the diameter of the particles, up to 65% while using nanosecond laser pulses. When the ablated particles were carried in argon into an ICP-MS, the Zn and Al signals intensities were greater by factors of {approx} 50 and {approx} 12 for fs vs. ns ablation. Femtosecond pulsed ablation also reduced temporal fluctuations in the {sup 66}Zn transient signal by a factor of ten compared to nanosecond laser pulses.

  8. Plume dynamics in femtosecond laser ablation of metals

    SciTech Connect

    Donnelly, T.; Lunney, J. G. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Amoruso, S.; Bruzzese, R.; Wang, X. [Coherentia CNR-INFM and Dipartimento di Scienze Fisiche, Universita degli Studi di Napoli Fedrico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126, Napoli (Italy)

    2010-10-08

    In femtosecond laser ablation the plume has two components: a faster-moving plasma part and a slower nanoparticle plume which contains most of the ablated material. This paper describes the results of experiments to comprehensively characterize the plume in laser ablation of Ni with {approx_equal}300 fs pulses at 527 nm. Both single-pulse and double-pulse irradiation was used. The laser ablation depth was measured using white light interferometry. The dynamics of the plasma part of the ablation plume was measured using Langmuir ion probes. The shape of the overall ablation plume was recorded by depositing a thin film on a transparent substrate and measuring the thickness distribution. The expansion of the plasma plume is well described by the Anismov isentropic model of plume expansion. Just above the ablation threshold, the nanoparticle plume is also well described by the Anisimov expansion model. However, at higher fluence a wider plume is formed, perhaps due to the pressure exerted by plasma. For double-pulse ablation it is observed that as the second pulse is delayed beyond {approx_equal}20 ps the ablation depth is reduced and the ion yield is increased. This behaviour is due to reheating of the nascent plasma plume produced by the first pulse. This generates a pressure pulse that acts as a tamper which impedes the fragmentation and ablation of deeper layers of material.

  9. CO2 TEA Laser-Enhanced Laser Ablation Molecular Isotopic Spectrometry (TELLAMIS)

    NASA Astrophysics Data System (ADS)

    Brown, Staci R.; Akpovo, Charlemagne A.; Ford, Alan; Herbert, Kenley; Johnson, Lewis

    2014-03-01

    Recently, it has been shown that the relative abundance of isotopes in enriched materials can be determined via laser-induced breakdown spectroscopy (LIBS) in a technique known as laser-ablation molecular isotopic spectroscopy (LAMIS). The original LAMIS work has focused on single-pulse (SP) LIBS for the excitation. However, dual-pulse (DP) LIBS reduces shot-to-shot variation and can lower detection limits of an element by about an order of magnitude or more. It also has the potential to improve the accuracy of the determination of the relative abundances of isotopes in LAMIS by minimizing the signal-to-noise ratio. In this work, a DP-LIBS technique for improving LAMIS relative-abundance information from a sample is presented. The new technique, called (TEA) Transverse-Excited breakdown in Atmosphere Laser-Enhanced Laser Ablation Molecular Isotopic Spectrometry (TELLAMIS), uses a carbon dioxide (CO2) laser to increase the breakdown emission from LIBS in the LAMIS method. This technique is demonstrated on a collection of relative abundance isotopes of boron- 10 and boron-11 in varying concentrations in boric acid. Least-squares fitting to theoretical models are used to deduce plasma parameters and understand reproducibility of results. DTRA.

  10. Infrared diode laser spectroscopy

    Microsoft Academic Search

    S. Civis; J. Cihelka; I. Matulková

    2010-01-01

    Three types of lasers (double-heterostructure 66 K InAsSb\\/InAsSbP laser diode, room temperature, multi quantum wells with\\u000a distributed feedback (MQW with DFB) (GaInAsSb\\/AlGaAsSb based) diode laser and vertical cavity surface emitting lasers (VCSELs)\\u000a (GaSb based) have been characterized using Fourier transform emission spectroscopy and compared. The photoacoustic technique\\u000a was employed to determine the detection limit of formaldehyde (less than 1 ppmV)

  11. A new model of pulsed laser ablation and plasma shielding

    Microsoft Academic Search

    Duanming-Zhang; Dan Liu; Zhihua-Li; Sipu-Hou; Boming-Yu; Li Guan; Xinyu-Tan; Li Li

    2005-01-01

    A new theoretical model of pulsed laser ablation has been developed, which studies the characteristics of laser–plasma interaction and the effect of plasma shielding in the ablation process. Two different absorption processes are considered, namely inverse bremsstrahlung and photoionization of excited species, also plasma radiation is included. The model is used to simulate 25ns square pulsed laser irradiation on YBa2Cu3O7

  12. Renaissance of laser interstitial thermal ablation.

    PubMed

    Missios, Symeon; Bekelis, Kimon; Barnett, Gene H

    2015-03-01

    Laser interstitial thermal therapy (LITT) is a minimally invasive technique for treating intracranial tumors, originally introduced in 1983. Its use in neurosurgical procedures was historically limited by early technical difficulties related to the monitoring and control of the extent of thermal damage. The development of magnetic resonance thermography and its application to LITT have allowed for real-time thermal imaging and feedback control during laser energy delivery, allowing for precise and accurate provision of tissue hyperthermia. Improvements in laser probe design, surgical stereotactic targeting hardware, and computer monitoring software have accelerated acceptance and clinical utilization of LITT as a neurosurgical treatment alternative. Current commercially available LITT systems have been used for the treatment of neurosurgical soft-tissue lesions, including difficult to access brain tumors, malignant gliomas, and radiosurgery-resistant metastases, as well as for the ablation of such lesions as epileptogenic foci and radiation necrosis. In this review, the authors aim to critically analyze the literature to describe the advent of LITT as a neurosurgical, laser excision tool, including its development, use, indications, and efficacy as it relates to neurosurgical applications. PMID:25727222

  13. Wavelength-Dependent Collagen Fragmentation during Mid-IR Laser Ablation

    PubMed Central

    Xiao, Yaowu; Guo, Mingsheng; Parker, Kevin; Hutson, M. Shane

    2006-01-01

    Mid-infrared free-electron lasers have proven adept in surgical applications. When tuned to wavelengths between 6 and 7 ?m, such lasers remove defined volumes of soft tissue with very little collateral damage. Previous attempts to explain the wavelength-dependence of collateral damage have invoked a wavelength-dependent loss of protein structural integrity. However, the molecular nature of this structural failure has been heretofore ill-defined. In this report, we evaluate several candidates for the relevant transition by analyzing the nonvolatile debris ejected during ablation. Porcine corneas were ablated with a free-electron laser tuned to 2.77 or 6.45 ?m—wavelengths with matched absorption coefficients for hydrated corneas that respectively target either tissue water or protein. The debris ejected during these ablations was characterized via gel electrophoresis, as well as Fourier transform infrared spectroscopy, micro-Raman and 13C-NMR spectroscopy. We find that high-fluence (240 J/cm2) ablation at 6.45 ?m, but not at 2.77 ?m, leads to protein fragmentation accompanied by the accumulation of nitrile and alkyne species. The candidate transition most consistent with these observations is scission of the collagen protein backbone at N-alkylamide bonds. Identifying this transition is a key step toward understanding the observed wavelength-dependence of collateral damage in mid-infrared laser ablation. PMID:16714345

  14. Vacuum ultraviolet laser-induced breakdown spectroscopy analysis of polymers

    Microsoft Academic Search

    Juraj Jasik; Johannes Heitz; Johannes D. Pedarnig; Pavel Veis

    2009-01-01

    Laser-induced breakdown spectroscopy (LIBS) in the vacuum ultraviolet range (VUV, ?<200nm) is employed for the detection of trace elements in polyethylene (PE) that are difficult to detect in the UV\\/VIS range. For effective laser ablation of PE, we use a F2 laser (wavelength ?=157nm) with a laser pulse length of 20ns, a pulse energy up to 50mJ, and pulse repetition

  15. Surface structure analysis of ZnO nano-particles fabricated by pulsed Nd: YAG laser ablation under plasma circumstance

    Microsoft Academic Search

    Qiang Ma; A. Ogino; Qiongrong Ou; M. Nagatsu

    2009-01-01

    In this letter, zinc oxide (ZnO) nanophosphors have been fabricated in oxygen\\/nitrogen plasma circumstance by Zn or ZnO targets using pulsed Nd:YAG laser ablation. Cathodoluminescence (CL) technique with energy-controlled electron beams, combined with X-ray diffraction (XRD) and X-ray photoemission spectroscopy (XPS) analyses, was used to study the structure of nano-sized ZnO particles fabricated by YAG laser ablation. The crystalline structure

  16. Laser ablation system, and method of decontaminating surfaces

    DOEpatents

    Ferguson, Russell L. (Idaho Falls, ID); Edelson, Martin C. (Ames, IA); Pang, Ho-ming (Ames, IA)

    1998-07-14

    A laser ablation system comprising a laser head providing a laser output; a flexible fiber optic cable optically coupled to the laser output and transmitting laser light; an output optics assembly including a nozzle through which laser light passes; an exhaust tube in communication with the nozzle; and a blower generating a vacuum on the exhaust tube. A method of decontaminating a surface comprising the following steps: providing an acousto-optic, Q-switched Nd:YAG laser light ablation system having a fiber optically coupled output optics assembly; and operating the laser light ablation system to produce an irradiance greater than 1.times.10.sup.7 W/cm.sup.2, and a pulse width between 80 and 170 ns.

  17. Corneal ablation using the pulse stretched free electron laser

    Microsoft Academic Search

    Mark A. Mackanos; Karen M. Joos; John A. Kozub; E. D. Jansen

    2005-01-01

    The Mark-III Free Electron Laser (FEL), tuned to lambda=6.45 mum has been demonstrated to provide for efficient ablation in ocular and neural tissues with minimal collateral damage. To date, the role of the FEL pulse structure on the mechanism of ablation has not been determined. In an effort to study the role of the FEL micropulse on the ablation of

  18. Picosecond laser ablation of nickel-based superalloy C263

    Microsoft Academic Search

    N. G. Semaltianos; W. Perrie; J. Cheng; M. Sharp; G. Dearden; K. G. Watkins

    2010-01-01

    Picosecond laser (10.4 ps, 1064 nm) ablation of the nickel-based superalloy C263 is investigated at different pulse repetition\\u000a rates (5, 10, 20, and 50 kHz). The two ablation regimes corresponding to ablation dominated by the optical penetration depth\\u000a at low fluences and of the electron thermal diffusion length at high fluences are clearly identified from the change of the\\u000a surface morphology of single

  19. Analysis and removal of ITER relevant materials and deposits by laser ablation

    NASA Astrophysics Data System (ADS)

    Xiao, Qingmei; Huber, Alexander; Philipps, Volker; Sergienko, Gennady; Gierse, Niels; Mertens, Philippe; Hai, Ran; Ding, Hongbin

    2014-12-01

    The analysis of the deposition of eroded wall material on the plasma-facing materials in fusion devices is one of the crucial issues to maintain the plasma performance and to fulfill safety requirements with respect to tritium retention by co-deposition. Laser ablation with minimal damage to the plasma facing material is a promising method for in situ monitoring and removal of the deposition, especially for plasma-shadowed areas which are difficult to reach by other cleaning methods like plasma discharge. It requires the information of ablation process and the ablation threshold for quantitative analysis and effective removal of the different deposits. This paper presents systemic laboratory experimental analysis of the behavior of the ITER relevant materials, graphite, tungsten, aluminum (as a substitution of beryllium) and mixed deposits ablated by a Nd:YAG laser (1064 nm) with different energy densities (1-27 J/cm2, power density 0.3-3.9 GW/cm2). The mixed deposits consisted of W-Al-C layer were deposited on W substrate by magnetron sputtering and arc plasma deposition. The aim was to select the proper parameters for the quantitative analysis and for laser removal of the deposits by investigating the ablation efficiency and ablation threshold for the bulk materials and deposits. The comparison of the ablation and saturation energy thresholds for pure and mixed materials shows that the ablation threshold of the mixed layer depends on the concentration of the components. We propose laser induced breakdown spectroscopy for determination of the elemental composition of deposits and then we select the laser parameters for the layer removal. Comparison of quantitative analysis results from laboratory to that from TEXTOR shows reasonable agreements. The dependence of the spectra on plasma parameters and ambient gas pressure is investigated.

  20. Osteoid Osteoma: Experience with Laser- and Radiofrequency-Induced Ablation

    SciTech Connect

    Gebauer, Bernhard [Charite, Medical University Berlin, Department of Radiology (Germany)], E-mail: bernhard.gebauer@charite.de; Tunn, Per-Ulf [Charite, Medical University Berlin, Department of Surgery and Surgical Oncology (Germany); Gaffke, Gunnar [Charite, Medical University Berlin, Department of Radiology (Germany); Melcher, Ingo [Charite, Medical University Berlin, Campus Virchow-Clinic, Department of Trauma and Reconstructive Surgery (Germany); Felix, Roland; Stroszczynski, Christian [Charite, Medical University Berlin, Department of Radiology (Germany)

    2006-04-15

    The purpose of this study was to analyze the clinical outcome of osteoid osteoma treated by thermal ablation after drill opening. A total of 17 patients and 20 procedures were included. All patients had typical clinical features (age, pain) and a typical radiograph showing a nidus. In 5 cases, additional histological specimens were acquired. After drill opening of the osteoid osteoma nidus, 12 thermal ablations were induced by laser interstitial thermal therapy (LITT) (9F Power-Laser-Set; Somatex, Germany) and 8 ablations by radiofrequency ablation (RFA) (RITA; StarBurst, USA). Initial clinical success with pain relief has been achieved in all patients after the first ablation. Three patients had an osteoid osteoma recurrence after 3, 9, and 10 months and were successfully re-treated by thermal ablation. No major complication and one minor complication (sensible defect) were recorded. Thermal ablation is a safe and minimally invasive therapy option for osteoid osteoma. Although the groups are too small for a comparative analysis, we determined no difference between laser- and radiofrequency-induced ablation in clinical outcome after ablation.

  1. Synthesis of Nickel Nanomaterial by Pulsed Laser Ablation in Liquid Medium and its Characterization

    SciTech Connect

    Gopal, R.; Singh, S. C.; Swarnkar, R. K. [Laser Spectroscopy and Nanomaterials Lab, Department of Physics, University of Allahabad, Allahabad-211002 (India); Singh, M. K.; Agarwal, A. [Department of Physics, M. N. National Institute of Technology, Allahabad-211004 (India)

    2009-06-29

    Laser ablation of nickel nanoparticles suspended in double deionized water has been studied using Nd:YAG laser (355 nm) with energy 30 mJ/pulse. Produced nanoparticles are analyzed by UV-visible absorption spectroscopy at certain interval (0, 20, 40, 60 minute). The particles are characterized by Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). TEM image shows that particles have crystal like structure and these particles are in the range of 20 nm to 50 nm.

  2. Infrared Laser Ablation Atmospheric Pressure Photoionization Mass Spectrometry

    E-print Network

    Vertes, Akos

    Infrared Laser Ablation Atmospheric Pressure Photoionization Mass Spectrometry Anu Vaikkinen ablation atmo- spheric pressure photoionization (LAAPPI), a novel atmospheric pressure ion source for mass analytes are desolvated and ionized in the gas-phase by atmospheric pressure photoionization using a 10 e

  3. Transient States of Matter during Short Pulse Laser Ablation

    Microsoft Academic Search

    K. Sokolowski-Tinten; J. Bialkowski; A. Cavalleri; D. von der Linde; A. Oparin; J. Meyer-Ter-Vehn; S. I. Anisimov

    1998-01-01

    Short pulse laser ablation of semiconductors and metals is studied by means of ultrafast time-resolved microscopy. The characteristic stages of the conversion of solid material into hot fluid matter undergoing ablation are identified. Initially metallic material transforms during the expansion into a transparent state with a high index of refraction.

  4. Boron carbonitride films deposited by pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Perrone, A.; Caricato, A. P.; Luches, A.; Dinescu, M.; Ghica, C.; Sandu, V.; Andrei, A.

    1998-08-01

    Boron carbonitride (BCN) thin films were deposited on Si (100) substrates at room temperature by sequential pulsed laser ablation (PLA) of graphite and hexagonal boron nitride (h-BN) targets in vacuum and in nitrogen atmosphere in the pressure range 1-100 Pa. Different analysis techniques as transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) pointed out the synthesis of h-BCN and c-BCN. The grain size of the crystalline c-BCN phase was estimated to be in the range 30-80 nm. The size of the crystallites in h-BCN phase was 4.6 ?m, with a transversal dimension of about 30 nm. Complementary microhardness measurements evidenced the high microhardness (values up to 2.9 GPa) of the deposited films.

  5. Production of silver nanoparticles by laser ablation in open air

    NASA Astrophysics Data System (ADS)

    Boutinguiza, M.; Comesaña, R.; Lusquiños, F.; Riveiro, A.; del Val, J.; Pou, J.

    2015-05-01

    Silver nanoparticles have attracted much attention as a subject of investigation due to their well-known properties, such as good conductivity, antibacterial and catalytic effects, etc. They are used in many different areas, such as medicine, industrial applications, scientific investigation, etc. There are different techniques for producing Ag nanoparticles, chemical, electrochemical, sonochemical, etc. These methods often lead to impurities together with nanoparticles or colloidal solutions. In this work, laser ablation of solids in open air conditions (LASOA) is used to produce silver nanoparticles and collect them on glass substrates. Production and deposition of silver nanoparticles are integrated in the same step to reduce the process. The obtained particles are analysed and the nanoparticles formation mechanism is discussed. The obtained nanoparticles were characterized by means of transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV/VIS absorption spectroscopy. The obtained nanoparticles consisted of Ag nanoparticles showing rounded shape with diameters ranging from few to 50 nm

  6. Selective material ablation by the TEA CO2 laser

    NASA Astrophysics Data System (ADS)

    Sumiyoshi, Tetsumi; Shiratori, Akira; Ninomiya, Yutaka; Obara, Minoru

    1995-03-01

    This paper reports two topics in the material processing using TEA CO2 lasers. We demonstrated selective ablation of hydrogenated amorphous silicon (a-Si:H) thin layer on a quartz substrate by the second harmonic (SH) radiation of TEA CO2 laser generated by AgGaSe2 nonlinear crystal. Si-H bonds contained in a-Si:H strongly absorb the 5 micrometers SH radiation and resulted in the selective ablation of the a-Si:H layer. The successful ablation processing of ethylenetetrafluoroethylene (ETFE) copolymer by the 9.6 micrometers fundamental wavelength TEA CO2 laser is also reported. Only ETFE thin film adhered to an aluminum substrate can be ablated by the TEA CO2 laser.

  7. Double-pulse nanosecond laser ablation of silicon in water

    NASA Astrophysics Data System (ADS)

    Momeni, A.; Mahdieh, M. H.

    2015-07-01

    This work was conducted experimentally to investigate the material removal rate and its mechanisms during the single-pulse and double-pulse nanosecond laser ablation of a silicon wafer in distilled water. The laser ablation processes were performed under the same experimental conditions with the same total pulse energy (E single pulse = E double pulse). The amount of ablated material was estimated for all of the processes based on measuring the dimensions (depths and widths) and volumes of the laser-induced craters on the silicon wafer. The results indicate that double-pulsed laser processing can result in a higher material removal rate compared to the more common single-pulse process, when the inter-pulse delay time is less than the pulse duration. The higher ablation yield in the double-pulse process can be due to the higher coupling efficiency of the second laser pulse with the melted target induced by the laser pre-pulse, leading to the more efficient laser energy absorption and deposition within the irradiated region. The double-pulse nanosecond laser processing with delay time of ~5?ns not only results in a higher material removal rate, but also leads to preparation of silicon nanoparticles with a greater mean particle size compared to that of the more common single-pulse laser ablation process.

  8. [Transurethral noncontact laser ablation of the large prostate].

    PubMed

    Xue, J; Zhuang, H; Wang, J

    1996-08-01

    42 cases of the large benign hypertrophy of the prostate were treated by transurethral noncontact laser ablation. The results of the patients followed up no less than six months and treatment were reported. The technique of the procedure and its related problems were described and our experience was presented. If we use the technique of the procedure skill fully, noncontact laser ablation of large benign hypertrophy of the prostate is safe and effective. PMID:9594203

  9. Laser ablation of iron: A comparison between femtosecond and picosecond laser pulses

    SciTech Connect

    Shaheen, M. E. [Great Lakes Institute for Environmental Research (GLIER), University of Windsor, Windsor, Ontario N9B 3P4 (Canada) [Great Lakes Institute for Environmental Research (GLIER), University of Windsor, Windsor, Ontario N9B 3P4 (Canada); Department of Physics, Faculty of Sciences, Tanta University, Tanta (Egypt); Gagnon, J. E.; Fryer, B. J. [Great Lakes Institute for Environmental Research (GLIER), University of Windsor, Windsor, Ontario N9B 3P4 (Canada) [Great Lakes Institute for Environmental Research (GLIER), University of Windsor, Windsor, Ontario N9B 3P4 (Canada); Department of Earth and Environmental Sciences, University of Windsor, Windsor, Ontario N9B 3P4 (Canada)

    2013-08-28

    In this study, a comparison between femtosecond (fs) and picosecond (ps) laser ablation of electrolytic iron was carried out in ambient air. Experiments were conducted using a Ti:sapphire laser that emits radiation at 785 nm and at pulse widths of 110 ps and 130 fs, before and after pulse compression, respectively. Ablation rates were calculated from the depth of craters produced by multiple laser pulses incident normally to the target surface. Optical and scanning electron microscopy showed that picosecond laser pulses create craters that are deeper than those created by the same number of femtosecond laser pulses at the same fluence. Most of the ablated material was ejected from the ablation site in the form of large particles (few microns in size) in the case of picosecond laser ablation, while small particles (few hundred nanometers) were produced in femtosecond laser ablation. Thermal effects were apparent at high fluence in both femtosecond and picosecond laser ablation, but were less prevalent at low fluence, closer to the ablation threshold of the material. The quality of craters produced by femtosecond laser ablation at low fluence is better than those created at high fluence or using picosecond laser pulses.

  10. Patterning microconductor using nanosecond laser ablation of metal nanoparticle film

    NASA Astrophysics Data System (ADS)

    Han, Sewoon; Lim, Taewong; Chung, Jaewon; Ko, Seung H.; Grigoropoulos, Costas P.; Kim, Dongjo; Moon, Jooho

    2007-02-01

    Ablation of metal nanoparticle film using frequency doubled Nd:YAG nanosecond laser is explored to apply for trimming drop on demand (DOD) inkjet printed electrical micro-conductor for flexible electronics. While elevated rim structure due to expulsion of molten pool is observed in sintered nanoparticle film, the ablation of unsintered nanoparticle film results in a Gaussian-shaped ablation profile, so that a clean precise patterning is possible. In addition, the ablation fluence threshold of unsintered metal nanoparticle film is at least ten times lower than that of a corresponding metal film. Therefore, by using nanosecond laser ablation, inkjet printed metal nanoparticles compatible for flexible polymer can be patterned efficiently with a high resolution.

  11. Laser ablation of a platinum target in water. I. Ablation mechanisms

    SciTech Connect

    Nichols, William T.; Sasaki, Takeshi; Koshizaki, Naoto [Nanoarchitectonics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan)

    2006-12-01

    This is the first in a series of three papers aimed at better understanding the processes that lead to nanomaterial formation during laser ablation of solid targets in liquids. Here we study the variation of the target surface morphology versus laser fluence and wavelength in order to suggest an ablation mechanism. A key finding is that an explosive ablation mechanism is prominent for a wide range of laser fluences for all wavelengths tested. Interestingly, however, ultraviolet (355 nm) and infrared (1064 nm) wavelengths show characteristically different explosive behaviors. In the infrared case, numerous large craters with diameters around 20 {mu}m form at localized points within the laser irradiated area. In contrast, ultraviolet ablation results in a striking transition to nanoscale surface roughness across the entire irradiated area. This texture is attributed to spinodal decomposition at the molten target surface. We propose that the wavelength and fluence dependence of the ablation craters can be explained by the amount of energy absorbed in the target. The consequences of the ablation mechanism for nanomaterial synthesis are discussed.

  12. Investigation of plumes produced by material ablation with two time-delayed femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Noël, S.; Axente, E.; Hermann, J.

    2009-09-01

    We experimentally investigated and herewith reported the results of laser ablation of copper and gold with two time-delayed femtosecond laser pulses at 800 nm in vacuum. The ablation plume dynamic was monitored by fast plume imaging and time- and space-resolved optical emission spectroscopy. Optical microscopy was used to follow the ablation depth as a function of the delay between the two laser pulses. Nanoparticles deposition on mica substrates was analysed by atomic force microscopy. We estimate roughly the plume's atomization degree - that is the mass fraction of atomized material over the total ablated mass - from the relative intensities of radiation emitted from atoms and nanoparticles. It is shown that the atomization degree depends critically on the time delay between both laser pulses and on the characteristic time of electron-lattice relaxation. The increase of the atomization degree is accompanied by the decrease of the ablation depth. Atomic force microscopy measurements confirm the partial atomization of nanoparticles, as the analyses of particle deposition on mica substrates show a large decrease of the number of nanoparticles for large delay between the two pulses.

  13. An x-ray probe of nickel nanoparticles generated by laser ablation

    NASA Astrophysics Data System (ADS)

    Lehmann, C. S.; Doumy, G.; Southworth, S. H.; March, A. M.; Dichiara, A. D.; Gao, Y.; Kanter, E. P.; Krässig, B.; Moonshiram, D.; Young, L.; Chapman, K. W.; Chupas, P. J.

    2014-05-01

    A plume of nickel atoms and nanoparticles can be generated by an intense laser pulse hitting a solid nickel surface. We set up a Ni ablation source in a vacuum chamber on an x-ray beamline at the Advanced Photon Source and used x-ray absorption, x-ray emission, and ion spectroscopies to probe the ablation plume at x-ray energies above the Ni K-edge at 8.33 keV. The laser and x-ray pulses were overlapped in time and space with variable delay to measure the time evolution of the ablation plume. Measurements of the charge states produced by x-ray absorption were not possible due to the intense prompt ions ejected in the ablation process. However, Ni K ? x-ray emission was measured as functions of laser fluence and pump-probe delay. The fluorescence yield was also used to record the near-edge x-ray absorption spectrum of the nanoparticles in the plume. The nanoparticles were collected and their diameters were determined to be ~9 nm from x-ray scattering pair-distribution-function measurements. The experiments demonstrate the use of x-ray techniques to characterize laser ablation processes. Work supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, US Dept of Energy, Contract DE-AC02-06CH11357.

  14. Reflection of femtosecond laser light in multipulse ablation of metals

    SciTech Connect

    Vorobyev, A. Y.; Guo Chunlei [Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)

    2011-08-15

    The shot-to-shot reflectance of high-intensity laser light is studied as a function of both the number of laser shots and laser fluence in multipulse ablation of a metal when the irradiated surface undergoes structural changes from an initially smooth surface to a deep crater. Our study shows that the reflectance of the irradiated surface significantly decreases due to the high intensity of laser pulses and the laser-induced surface structures in ablation regimes typically used for femtosecond laser processing of materials. The high-intensity effect dominates in the reflection reduction at low numbers of laser shots when laser-induced surface structures do not cause the reflectance to decrease noticeably. With increasing the number of laser shots, the structural effect comes into play, and both high-intensity and structural effects quickly reduce the reflectance of the sample to a low value.

  15. Ablation enhancement of silicon by ultrashort double-pulse laser ablation

    SciTech Connect

    Zhao, Xin; Shin, Yung C. [Center for Laser-Based Manufacturing, School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2014-09-15

    In this study, the ultrashort double-pulse ablation of silicon is investigated. An atomistic simulation model is developed to analyze the underlying physics. It is revealed that the double-pulse ablation could significantly increase the ablation rate of silicon, compared with the single pulse ablation with the same total pulse energy, which is totally different from the case of metals. In the long pulse delay range (over 1?ps), the enhancement is caused by the metallic transition of melted silicon with the corresponding absorption efficiency. At ultrashort pulse delay (below 1?ps), the enhancement is due to the electron excitation by the first pulse. The enhancement only occurs at low and moderate laser fluence. The ablation is suppressed at high fluence due to the strong plasma shielding effect.

  16. Direct laser interference ablating nanostructures on organic crystals.

    PubMed

    Fang, Hong-Hua; Ding, Ran; Lu, Shi-Yang; Wang, Lei; Feng, Jing; Chen, Qi-Dai; Sun, Hong-Bo

    2012-02-15

    Two-beam interference ablation of 1,4-Bis(4-methylstyryl)benzene organic crystal by short laser pulses (10 ns, 355 nm) is presented. The influence of laser fluence, interference period, and pulse number on the morphology have been studied. The morphology is closely associated with the molecular interactions in the crystals, and it could be well controlled by adjusting the laser fluence and pulses number. Through interference ablating the crystals with high fluence pulses, and then treated with low fluence laser pulses, grating structures with smooth surface could be fabricated without any additional process. PMID:22344148

  17. Ultraviolet versus infrared: Effects of ablation laser wavelength on the expansion of laser-induced plasma into one-atmosphere argon gas

    NASA Astrophysics Data System (ADS)

    Ma, Qianli; Motto-Ros, Vincent; Laye, Fabrice; Yu, Jin; Lei, Wenqi; Bai, Xueshi; Zheng, Lijuan; Zeng, Heping

    2012-03-01

    Laser-induced plasma from an aluminum target in one-atmosphere argon background has been investigated with ablation using nanosecond ultraviolet (UV: 355 nm) or infrared (IR: 1064 nm) laser pulses. Time- and space-resolved emission spectroscopy was used as a diagnostics tool to have access to the plasma parameters during its propagation into the background, such as optical emission intensity, electron density, and temperature. The specific feature of nanosecond laser ablation is that the pulse duration is significantly longer than the initiation time of the plasma. Laser-supported absorption wave due to post-ablation absorption of the laser radiation by the vapor plume and the shocked background gas plays a dominant role in the propagation and subsequently the behavior of the plasma. We demonstrate that the difference in absorption rate between UV and IR radiations leads to different propagation behaviors of the plasma produced with these radiations. The consequence is that higher electron density and temperature are observed for UV ablation. While for IR ablation, the plasma is found with lower electron density and temperature in a larger and more homogenous axial profile. The difference is also that for UV ablation, the background gas is principally evacuated by the expansion of the vapor plume as predicted by the standard piston model. While for IR ablation, the background gas is effectively mixed to the ejected vapor at least hundreds of nanoseconds after the initiation of the plasma. Our observations suggest a description by laser-supported combustion wave for the propagation of the plasma produced by UV laser, while that by laser-supported detonation wave for the propagation of the plasma produced by IR laser. Finally, practical consequences of specific expansion behavior for UV or IR ablation are discussed in terms of analytical performance promised by corresponding plasmas for application with laser-induced breakdown spectroscopy.

  18. Photoluminescent zinc oxide polymer nanocomposites fabricated using picosecond laser ablation in an organic solvent

    NASA Astrophysics Data System (ADS)

    Wagener, Philipp; Faramarzi, Shamsolzaman; Schwenke, Andreas; Rosenfeld, Rupert; Barcikowski, Stephan

    2011-06-01

    Nanocomposites made of ZnO nanoparticles dispersed in thermoplastic polyurethane were synthesized using picosecond laser ablation of zinc in a polymer-doped solution of tetrahydrofuran. The pre-added polymer stabilizes the ZnO nanoparticles in situ during laser ablation by forming a polymer shell around the nanoparticles. This close-contact polymer shell has a layer thickness up to 30 nm. Analysis of ZnO polyurethane nanocomposites using optical spectroscopy, high resolution transmission electron microscopy and X-ray diffraction revealed that oxidized and crystalline ZnO nanoparticles were produced. Those nanocomposites showed a green photoluminescence emission centred at 538 nm after excitation at 350 nm, which should be attributed to oxygen defects generated during the laser formation mechanism of the monocrystalline nanoparticles. Further, the influence of pulse energy and polymer concentration on the production rate, laser fluence and energy-specific mass productivity was investigated.

  19. Enhancement of optical emission signal in double-pulse laser ablation of titanium in vacuum

    NASA Astrophysics Data System (ADS)

    Krstulovi?, Nikša; Biš?an, Marijan; Miloševi?, Slobodan

    2015-04-01

    Laser plasma of Ti produced in vacuum was studied by optical emission spectroscopy. The plasma was produced in a single-pulse and a double-pulse mode of ablation in a collinear configuration of laser beams. It was shown that there is a significant enhancement in emission intensity in double-pulse mode. Moreover, depending on the delay time between laser pulses in double-pulse mode signal enhancement (up to 18-fold) was further optimized. Measurement of emission from neutral and ionized Ti atoms showed that there is an optimal delay time for which emission enhancement is maximal, for both ions and neutrals. It was shown that using double-pulse laser ablation the enhancement is mostly pronounced when emission from plasma near the target surface is taken into account. This increases the limit of detection and the signal/background ratio.

  20. Laser ablation inductively coupled plasma atomic emission spectrometry of a uranium-zirconium alloy: ablation properties and analytical behavior

    Microsoft Academic Search

    Phillip Goodall; Stephen G. Johnson; Elon Wood

    1995-01-01

    The ablation properties and analytical behavior of a uranium-zirconium alloy have been examined using tandem laser ablation\\/pneumatic nebulization sample introduction in conjunction with inductively coupled atomic emission spectrometry (LA-ICP-AES). An apparent change in composition of the laser ablation aerosol (1–15 GW cm?2 Zr deficient, 40–250 GW cm?2 Zr rich) is observed. This phenomenon is independent of laser wavelength. After collection

  1. Optical properties of petal-like aggregated nanocrystalline zinc oxide synthesized by laser ablation

    SciTech Connect

    Jafarkhani, P.; Chehrghani, A. [Iranian National Centre for Laser Science and Technology (INLC), PO Box: 14665-576, Tehran (Iran, Islamic Republic of)] [Iranian National Centre for Laser Science and Technology (INLC), PO Box: 14665-576, Tehran (Iran, Islamic Republic of); Torkamany, M.J., E-mail: mjtorkamany@inlc.ir [Iranian National Centre for Laser Science and Technology (INLC), PO Box: 14665-576, Tehran (Iran, Islamic Republic of)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Petal like ZnO nanocrystals are synthesized by high frequency laser ablation in water. Black-Right-Pointing-Pointer Optical band gap of ZnO nanocrystals was tunable by changing the laser pulse energy. Black-Right-Pointing-Pointer Nonlinear optical properties and limiting threshold were obtained by Z-scan technique. -- Abstract: The results of the investigations carried out on the third-order nonlinearity in zinc oxide (ZnO) nanocrystals (NCs) by Z-scan technique are included in this paper. ZnO NCs show negative nonlinearity and good nonlinear absorption behavior at 532 nm. The third-order optical susceptibility {chi}(3) increases with enlargement of NCs due to the size dependent enhancement of exciton oscillator strength. The synthesis of ZnO NCs was performed by laser ablation from a high-purity metallic target of Zn in distilled water medium. For the ablation process, a high frequency pulsed Nd:YAG laser was employed operating at 532 nm with 100 ns pulse duration. UV-vis absorption spectroscopy illustrated the enhancement of the size of ZnO NCs upon increasing the laser pulse energy applied in ablation process. Accordingly the corresponding optical band gap (E{sub g}) decrease by increasing the size of NCs. X-ray diffraction (XRD) associated with transmission electron microscopy (TEM) was utilized to characterize the crystalline phase and also for determining the ZnO NCs morphology.

  2. Ablation behaviors of carbon reinforced polymer composites by laser of different operation modes

    NASA Astrophysics Data System (ADS)

    Wu, Chen-Wu; Wu, Xian-Qian; Huang, Chen-Guang

    2015-10-01

    Laser ablation mechanism of Carbon Fiber Reinforced Polymer (CFRP) composite is of critical meaning for the laser machining process. The ablation behaviors are investigated on the CFRP laminates subject to continuous wave, long duration pulsed wave and short duration pulsed wave lasers. Distinctive ablation phenomena have been observed and the effects of laser operation modes are discussed. The typical temperature patterns resulted from laser irradiation are computed by finite element analysis and thereby the different ablation mechanisms are interpreted.

  3. Femtosecond laser ablation for controlling micro and nano structuration

    E-print Network

    Paris-Sud XI, Université de

    Femtosecond laser ablation for controlling micro and nano structuration Dissertation zur Erlangung of the interaction of femtosecond laser pulses with matter for micro- and nano-structuration and this by having, Nanobiotechnologie und Nanomedizin. Résumé succinct Le développement actuel de la technologie induit une constante

  4. Experimental investigation of ablation mechanisms involved in dry laser cleaning

    Microsoft Academic Search

    D. Grojo; A. Cros; Ph. Delaporte; M. Sentis

    2007-01-01

    The various ablation mechanisms possibly involved in ‘laser-particle-surface’ interaction were investigated by means of in situ diagnostics. Different kind of transparent and absorbing particles were irradiated by UV nanosecond laser pulses. Optical microscopy was employed to measure particle removal efficiencies and fluence thresholds. Fast imaging with the aid of an intensified charged coupled device (ICCD) camera was used to characterize

  5. Generation of low work function, stable compound thin films by laser ablation

    DOEpatents

    Dinh, Long N. (Concord, CA); McLean, II, William (Oakland, CA); Balooch, Mehdi (Berkeley, CA); Fehring, Jr., Edward J. (Dublin, CA); Schildbach, Marcus A. (Livermore, CA)

    2001-01-01

    Generation of low work function, stable compound thin films by laser ablation. Compound thin films with low work function can be synthesized by simultaneously laser ablating silicon, for example, and thermal evaporating an alkali metal into an oxygen environment. For example, the compound thin film may be composed of Si/Cs/O. The work functions of the thin films can be varied by changing the silicon/alkali metal/oxygen ratio. Low work functions of the compound thin films deposited on silicon substrates were confirmed by ultraviolet photoelectron spectroscopy (UPS). The compound thin films are stable up to 500.degree. C. as measured by x-ray photoelectron spectroscopy (XPS). Tests have established that for certain chemical compositions and annealing temperatures of the compound thin films, negative electron affinity (NEA) was detected. The low work function, stable compound thin films can be utilized in solar cells, field emission flat panel displays, electron guns, and cold cathode electron guns.

  6. Nanosecond Laser-Induced Thermal Diffusion during Laser Ablation of Epoxy from a Multilayered Surface

    NASA Astrophysics Data System (ADS)

    Zheng, H. Y.; Chen, Q.; Wang, X. C.; Tan, J. L.; Lim, G. C.

    Interference ring marks were observed on a copper substrate consisting of plated layers of Au, Pd and Ni after laser ablation of epoxy material from the top surface. These ring marks are the result of laser-induced surface oxidation and need to be avoided or minimized in order to improve the solder wettability on the treated surface. Studies of laser-induced thermal diffusion through the plated layers were carried out using a 532 nm Q-switch Nd:YAG laser. The major process variables investigated were the beam profile, pulse repetition rate and beam scan pattern. Secondary ion mass spectroscopy (SIMS) was used to obtain a depth profile of the laser-treated layers. It revealed that interfusion of Pd and Ni by diffusion occurred during laser irradiation. Calculations of thermal diffusion length and temperature rise of the metal layers without considering the accumulated thermal effect of overlapping pulses are presented in this article. The study results are useful for a better understanding of the process of laser removal of epoxy flashes on leadframe heatsink surfaces.

  7. Nonstoichiometric Titanium Oxides via Pulsed Laser Ablation in Water

    NASA Astrophysics Data System (ADS)

    Huang, Chang-Ning; Bow, Jong-Shing; Zheng, Yuyuan; Chen, Shuei-Yuan; Ho, New Jin; Shen, Pouyan

    2010-06-01

    Titanium oxide compounds TiO, Ti2O3, and TiO2 with a considerable extent of nonstoichiometry were fabricated by pulsed laser ablation in water and characterized by X-ray/electron diffraction, X-ray photoelectron spectroscopy and electron energy loss spectroscopy. The titanium oxides were found to occur as nanoparticle aggregates with a predominant 3+ charge and amorphous microtubes when fabricated under an average power density of ca. 1 × 108 W/cm2 and 1011 W/cm2, respectively followed by dwelling in water. The crystalline colloidal particles have a relatively high content of Ti2+ and hence a lower minimum band gap of 3.4 eV in comparison with 5.2 eV for the amorphous state. The protonation on both crystalline and amorphous phase caused defects, mainly titanium rather than oxygen vacancies and charge and/or volume-compensating defects. The hydrophilic nature and presumably varied extent of undercoordination at the free surface of the amorphous lamellae accounts for their rolling as tubes at water/air and water/glass interfaces. The nonstoichiometric titania thus fabricated have potential optoelectronic and catalytic applications in UV-visible range and shed light on the Ti charge and phase behavior of titania-water binary in natural shock occurrence.

  8. Nonstoichiometric Titanium Oxides via Pulsed Laser Ablation in Water.

    PubMed

    Huang, Chang-Ning; Bow, Jong-Shing; Zheng, Yuyuan; Chen, Shuei-Yuan; Ho, Newjin; Shen, Pouyan

    2010-01-01

    Titanium oxide compounds TiO,Ti2O3, and TiO2 with a considerable extent of nonstoichiometry were fabricated by pulsed laser ablation in water and characterized by X-ray/electron diffraction, X-ray photoelectron spectroscopy and electron energy loss spectroscopy. The titanium oxides were found to occur as nanoparticle aggregates with a predominant 3+ charge and amorphous microtubes when fabricated under an average power density of ca. 1 × 108W/cm2 and 1011W/cm2, respectively followed by dwelling in water. The crystalline colloidal particles have a relatively high content of Ti2+ and hence a lower minimum band gap of 3.4 eV in comparison with 5.2 eV for the amorphous state. The protonation on both crystalline and amorphous phase caused defects, mainly titanium rather than oxygen vacancies and charge and/or volume-compensating defects. The hydrophilic nature and presumably varied extent of undercoordination at the free surface of the amorphous lamellae accounts for their rolling as tubes at water/air and water/glass interfaces. The nonstoichiometric titania thus fabricated have potential optoelectronic and catalytic applications in UV-visible range and shed light on the Ti charge and phase behavior of titania-water binary in natural shock occurrence. PMID:20672115

  9. Resonant holographic measurements of laser ablation plume expansion in vacuum and argon gas backgrounds

    SciTech Connect

    Lindley, R.A. [Michigan Univ., Ann Arbor, MI (United States)

    1993-10-01

    This thesis discusses the following on resonant holographic measurements of laser ablation plume expansion: Introduction to laser ablation; applications of laser ablation; The study of plume expansion; holographic interferometry; resonant holographic interferometry; accounting for finite laser bandwidth; The solution for doppler broadening and finite bandwidth; the main optical table; the lumonics laser spot shape; developing and reconstructing the holograms; plume expansion in RF/Plasma Environments; Determining {lambda}{sub o}; resonant refraction effects; fringe shift interpretation; shot-to-shot consistency; laser ablation in vacuum and low pressure, inert, background gas; theoretically modeling plume expansion in vacuum and low pressure, inert, background gas; and laser ablation in higher pressure, inert, background gas.

  10. Nanometer thickness laser ablation for spatial control of cell attachment

    NASA Astrophysics Data System (ADS)

    Thissen, H.; Hayes, J. P.; Kingshott, P.; Johnson, G.; Harvey, E. C.; Griesser, H. J.

    2002-10-01

    We demonstrate here a new method to control the location of cells on surfaces in two dimensions, which can be applied to a number of biomedical applications including diagnostic tests and tissue engineered medical devices. Two-dimensional control over cell attachment is achieved by generation of a spatially controlled surface chemistry that allows control over protein adsorption, a process which mediates cell attachment. Here, we describe the deposition of thin allylamine plasma polymer coatings on silicon wafer and perfluorinated poly(ethylene-co-propylene) substrates, followed by grafting of a protein resistant layer of poly(ethylene oxide). Spatially controlled patterning of the surface chemistry was achieved in a fast, one-step procedure by nanometer thickness controlled laser ablation using a 248 nm excimer laser. X-ray photoelectron spectroscopy and atomic force microscopy were used to confirm the production of surface chemistry patterns with a resolution of approximately 1 µm, which is significantly below the dimensions of a single mammalian cell. Subsequent adsorption of the extracellular matrix proteins collagen I and fibronectin followed by cell culture experiments using bovine corneal epithelial cells confirmed that cell attachment is controlled by the surface chemistry pattern. The method is an effective tool for use in a number of in vitro and in vivo applications.

  11. Optical detection of slow excited neutrals in plasma-assisted excimer laser ablation

    SciTech Connect

    Mukherjee, P.; Sakthivel, P.; Witanachchi, S. [Univ. of South Florida, Tampa, FL (United States). Dept. of Physics

    1996-12-31

    The observation of a slow optically excited component in the excimer laser-ablated YBCO plume due to the presence of a biased ring electrode is reported. The temporal dynamics of the plume were investigated by using time-of-flight (TOF) optical emission spectroscopy (OES). Time-resolved emission signals reveal excitation and resultant fluorescence from slow-moving plume species in the presence of the discharge.

  12. Diagnostic du plasma d'ablation laser pour lacroissance de couches minces

    Microsoft Academic Search

    A. Basillais; R. Benzerga; E. Le Menn; J. Mathias; C. Boulmer-Leborgne; J. Perrière

    2003-01-01

    Dans ce travail, nous nous sommes intéressés à la croissance de films de nitrure d'aluminium par ablation laser d'une cible d'aluminium assistée par un plasma d'azote créé par une décharge RF. Parallèlement, la spectroscopie d'émission a été largement utilisée pour le diagnostic de la plume plasma et du plasma de décharge RF afin de trouver des informations permettant de suivre

  13. Laser ablation rate of hydroxylapatite in different atmospheres

    NASA Astrophysics Data System (ADS)

    Arias, J. L.; Mayor, M. B.; Pou, J.; León, B.; Pérez-Amor, M.

    2003-03-01

    Hydroxylapatite (Ca 10(PO 4) 6(OH) 2) is a calcium phosphate used as coating for dental and orthopaedic implants, because its composition and structure are similar to the mineral part of bone. Pulsed laser deposition has been applied as an alternative to the commercial technique for the production of hydroxylapatite coatings: plasma spraying. Hydroxylapatite targets were ablated at 0.9 J cm -2 using an ArF excimer laser (193 nm) at 20 Hz in order to investigate the ablation rate of hydroxylapatite in different atmospheres: water vapour, Ar and O 2. The ablation rate was measured by profilometry for different pressures in a range of 15-80 Pa. The ablation rate depends on the backscattering of the ablated particles by the molecules of the gas, which produces different amounts of re-deposited material on the target surface for each gas. The ablation rate in a water vapour atmosphere presents a particular behaviour due to the formation of different calcium phosphate phases from the original hydroxylapatite under ArF excimer laser irradiation as compared those formed in other ambient gases.

  14. Investigation of nanoparticle formation in a plasma produced by femtosecond laser ablation of gold

    SciTech Connect

    Spiga, P.; Hermann, J.; Itina, T.; Grojo, D. [LP3, UMR 6182 CNRS-Faculte des Sciences de Luminy, Case 917, F-13288 Marseille (France); Neamtu, D. [NILPRP- Laser Department, P.O. Box MG-36, R-76900 Bucharest (Romania); Pailharey, D.; Marine, W. [CRMCN, UPR CNRS 7251-Faculte des Sciences de Luminy, Case 901, F-13288 Marseille (France)

    2005-10-31

    The formation of nanoparticles in a plasma produced by the interaction of ultrashort laser pulses with gold has been investigated. Three different experimental techniques were employed. (i) The plume expansion was characterized using fast imaging with the aid of an intensified charge-coupled device. (ii) The plasma composition was analyzed using time- and space-resolved optical emission spectroscopy. (iii) The ablated material was deposited on mica substrates and analyzed by means of atomic force microscopy. As a result, the size-distribution and the overall number of nanoparticles were determined as a function of the laser energy density incident on the target surface. The detection of particles with sizes in the nanometer range supports theoretical modeling according to which phase explosion is the dominant mechanism of metal ablation by ultrashort laser pulses.

  15. Pulsed laser ablation of MoSi 2: gas phase analysis

    NASA Astrophysics Data System (ADS)

    Teghil, R.; D'Alessio, L.; Santagata, A.; Zaccagnino, M.; Ferro, D.

    2002-01-01

    The gaseous phase produced by laser ablation of a molybdenum silicide target has been analysed by time-of-flight mass spectrometry, emission spectroscopy and fast imaging performed by an ICCD camera, in order to obtain informations about the mechanisms involved in the laser deposition of MoSi 2 thin films. During laser ablation, the emission spectra indicate a target temperature of about 7200 K, while the mass spectra evidence the presence of clusters corresponding to the formula (MoSi 2) n with n up to 2. The results suggest that the possibility to deposit stoichiometric thin films is related to the composition of the plasma and, in particular to the presence of cluster with the right silicon molybdenum ratio. The presence of a large amount of clusters could be due to reactions in the plasma.

  16. Comparison of tissue ablation with pulsed holmium and thulium lasers

    Microsoft Academic Search

    NORMAN S. NISHIOKA; YACOV DOMANKEVITZ

    1990-01-01

    The ablation rates and tissue effects produced by a pulsed holmium laser (wavelength 2.12 ?m, pulse duration 250 ?s) and a pulsed thulium laser (wavelength 2.01 ?m, pulse duration 250 ?s) were compared. Because the absorption coefficient of water is almost three times greater at the shorter wavelength (65 versus 24 cm-1), the thulium laser should have a significantly lower

  17. Nanoscale patterning of graphene through femtosecond laser ablation

    SciTech Connect

    Sahin, R.; Akturk, S., E-mail: selcuk.akturk@itu.edu.tr [Department of Physics, Istanbul Technical University, Maslak 34469, Istanbul (Turkey); Simsek, E. [Electrical and Computer Engineering, The George Washington University, Washington, DC 20052 (United States)

    2014-02-03

    We report on nanometer-scale patterning of single layer graphene on SiO{sub 2}/Si substrate through femtosecond laser ablation. The pulse fluence is adjusted around the single-pulse ablation threshold of graphene. It is shown that, even though both SiO{sub 2} and Si have more absorption in the linear regime compared to graphene, the substrate can be kept intact during the process. This is achieved by scanning the sample under laser illumination at speeds yielding a few numbers of overlapping pulses at a certain point, thereby effectively shielding the substrate. By adjusting laser fluence and translation speed, 400?nm wide ablation channels could be achieved over 100??m length. Raster scanning of the sample yields well-ordered periodic structures, provided that sufficient gap is left between channels. Nanoscale patterning of graphene without substrate damage is verified with Scanning Electron Microscope and Raman studies.

  18. Nanostructures synthesis by femtosecond laser ablation of glasses

    NASA Astrophysics Data System (ADS)

    Vipparty, D.; Tan, B.; Venkatakrishnan, K.

    2012-10-01

    In this article, we investigate the variations in ablation dynamics that result in diverse nanostructures on SiO2 based glass samples. A three-dimensional fibrous nanoparticle agglomerate was observed on sodalime glass when exposed to femtosecond laser irradiation. The fused nanoparticles have diameters ranging from 30 nm to 70 nm. Long continuous nanofibers of extremely high aspect ratio (certain fibers up to 100 000:1) were obtained by exposing silica glass surface to femtosecond laser irradiation at MHz repetition rate in air. A nanostructure assembly comprising of nanofiber and nanoparticle agglomerates was also observed by ablating silica glass. From our experimental analysis, it was determined that variation in bandgap and material composition alters ablation dynamics and dictates the response of glass to femtosecond laser irradiation, ultimately leading to the formation of structures with varying morphology on silica and sodalime glass. The possible underlying mechanisms that produce such nanostructures on glass specimens have also been explored.

  19. Fabrication of iron oxide nanoparticles using laser ablation in liquids

    NASA Astrophysics Data System (ADS)

    Iwamoto, T.; Ishigaki, T.

    2013-06-01

    Nanoparticles of iron oxides were synthesized through the ablation of the bulk-targets of Fe, Fe3O4, and Fe2O3 in water by the irradiation of a Nd:YAG laser. Our samples prepared via the laser ablation method displayed small (ca. 1 nm in diameter) and large (over 5 nm in diameter) particles. The small particles were well-dispersed, whereas large particles were agglomerated. The FeO and Fe3O4 phases were formed in the synthesized powders irrespective of the kind of targets. The formation of the other phases, Fe and Fe2O3, changed depending on the the kind of targets used in the laser ablation. Poly(N-vinyl-2-pyrrolidone) (PVP) as a protective reagent was employed to disperse large particles in our samples, and accordingly, their dispersibility was improved as mole concentration of PVP increased.

  20. Evolution and imaging of nanoparticles observed in laser ablated carbon plume

    SciTech Connect

    Yadav, Dheerendra; Gupta, Varun; Thareja, Raj K. [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016 (UP) (India)

    2009-09-15

    We report evidence of nanoparticles formation in laser ablated carbon plasma created by irradiating a graphite target with nanosecond neodymium doped yttrium aluminum garnet laser. The temporal evolution and spatial distribution of C{sub 2} molecules in the plasma is studied using optical emission spectroscopy, dynamic imaging and laser induced fluorescence techniques. The laser induced fluorescence spectrum and imaging of C{sub 2} fluorescence corresponding to transition d {sup 3}PI{sub g}-a {sup 3}PI{sub u} (0, 1) (lambda=563.5 nm) is investigated by probing the expanding plume using a dye laser. The temporal evolution of ground state number density of C{sub 2} shows density varying from 2.6x10{sup 20}/m{sup 3} to 1.2x10{sup 22}/m{sup 3} on varying delay between the ablating and probe pulse from 200 to 600 ns. A peculiar bifurcation of carbon plume into two parts at approx270 ns after the formation of plasma is attributed to recombination of carbon species and formation of nanoparticles. This study may help in quantitatively understanding of formation of carbon molecular species and the nanoparticles produced in laser ablated carbon plume.

  1. Visual servoing of a laser ablation based cochleostomy

    NASA Astrophysics Data System (ADS)

    Kahrs, Lüder A.; Raczkowsky, Jörg; Werner, Martin; Knapp, Felix B.; Mehrwald, Markus; Hering, Peter; Schipper, Jörg; Klenzner, Thomas; Wörn, Heinz

    2008-03-01

    The aim of this study is a defined, visually based and camera controlled bone removal by a navigated CO II laser on the promontory of the inner ear. A precise and minimally traumatic opening procedure of the cochlea for the implantation of a cochlear implant electrode (so-called cochleostomy) is intended. Harming the membrane linings of the inner ear can result in damage of remaining organ functions (e.g. complete deafness or vertigo). A precise tissue removal by a laser-based bone ablation system is investigated. Inside the borehole the pulsed laser beam is guided automatically over the bone by using a two mirror galvanometric scanner. The ablation process is controlled by visual servoing. For the detection of the boundary layers of the inner ear the ablation area is monitored by a color camera. The acquired pictures are analyzed by image processing. The results of this analysis are used to control the process of laser ablation. This publication describes the complete system including image processing algorithms and the concept for the resulting distribution of single laser pulses. The system has been tested on human cochleae in ex-vivo studies. Further developments could lead to safe intraoperative openings of the cochlea by a robot based surgical laser instrument.

  2. Trace Element Microanalysis in Iron Meteorites by Laser Ablation ICPMS.

    PubMed

    Campbell, A J; Humayun, M

    1999-03-01

    A laser ablation microanalysis system has been developed that can analyze trace elements with a sensitivity in the ppb range, using a CETAC LSX-200 laser ablation system with a Finnigan Element. This capability has been applied to a set of iron meteorites to demonstrate the laser microprobe's analytical capability for the determination of platinum group elements (PGEs) with a spatial resolution of ?20 ?m, comparable to that of dynamic secondary ion mass spectrometry (SIMS). The laser is shown to provide an accurate means of solid sampling for magnetic sector inductively coupled plasma mass spectrometry (ICPMS), allowing the determination of bulk metal composition, chemical zoning within the sample, and depth profiling. Recovery of the chemical zoning in taenite lamellae was achieved for Ru, Rh, and Pd, which was not previously possible using SIMS. The methods presented here show that magnetic sector ICPMS can be successfully coupled to a laser ablation system, providing the advantages of higher sensitivity of the sector instrument, low background count rates (<0.1 counts/s), and flat-topped spectral peaks, while minimizing tradeoff against the speed of data acquisition required to handle the transient signals from the laser ablation system. PMID:21662764

  3. Combined optical tweezers and laser dissector for controlled ablation of functional connections in neural networks

    NASA Astrophysics Data System (ADS)

    Difato, Francesco; Dal Maschio, Marco; Marconi, Emanuele; Ronzitti, Giuseppe; Maccione, Alessandro; Fellin, Tommasso; Berdondini, Luca; Chieregatti, Evelina; Benfenati, Fabio; Blau, Axel

    2011-05-01

    Regeneration of functional connectivity within a neural network after different degrees of lesion is of utmost clinical importance. To test pharmacological approaches aimed at recovering from a total or partial damage of neuronal connections within a circuit, it is necessary to develop a precise method for controlled ablation of neuronal processes. We combined a UV laser microdissector to ablate neural processes in vitro at single neuron and neural network level with infrared holographic optical tweezers to carry out force spectroscopy measurements. Simultaneous force spectroscopy, down to the sub-pico-Newton range, was performed during laser dissection to quantify the tension release in a partially ablated neurite. Therefore, we could control and measure the damage inflicted to an individual neuronal process. To characterize the effect of the inflicted injury on network level, changes in activity of neural subpopulations were monitored with subcellular resolution and overall network activity with high temporal resolution by concurrent calcium imaging and microelectrode array recording. Neuronal connections have been sequentially ablated and the correlated changes in network activity traced and mapped. With this unique combination of electrophysiological and optical tools, neural activity can be studied and quantified in response to controlled injury at the subcellular, cellular, and network level.

  4. Fundamental Mechanisms of Pulsed Laser Ablation of Biological Tissue

    NASA Astrophysics Data System (ADS)

    Albagli, Douglas

    The ability to cut and remove biological tissue with short pulsed laser light, a process called laser ablation, has the potential to revolutionize many surgical procedures. Ablation procedures using short pulsed lasers are currently being developed or used in many fields of medicine, including cardiology, ophthalmology, dermatology, dentistry, orthopedics, and urology. Despite this, the underlying physics of the ablation process is not well understood. In fact, there is wide disagreement over whether the fundamental mechanism is primarily photothermal, photomechanical, or photochemical. In this thesis, both experimental and theoretical techniques are developed to explore this issue. The photothermal model postulates that ablation proceeds through vaporization of the target material. The photomechanical model asserts that ablation is initiated when the laser-induced tensile stress exceeds the ultimate tensile strength of the target. I have developed a three dimensional model of the thermoelastic response of tissue to short pulsed laser irradiation which allows the time dependent stress distribution to be calculated given the optical, thermal and mechanical properties of the target. A complimentary experimental technique has been developed to verify this model, measure the needed physical properties of the tissue, and record the thermoelastic response of the tissue at the onset of ablation. The results of this work have been widely disseminated to the international research community and have led to significant findings which support the photomechanical model of ablation of tissue. First, the energy deposited in tissue is an order of magnitude less than that required for vaporization. Second, unlike the one-dimensional thermoelastic model of laser-induced stress generation that has appeared in the literature, the full three-dimensional model predicts the development of significant tensile stresses on the surface of the target, precisely where ablation is observed to occur. Third, although the laser-induced temperature rise is modest, the magnitude of the stresses is sufficient to initiate mechanically destructive phenomenon. In hard materials, including bone, a gradual weakening of material with each successive laser pulse is observed and correlated with the formation of permanent microcracks within the material. In meniscus, a representative soft tissue, the growth and collapse of mechanically destructive cavitation bubbles is observed. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).

  5. Wavelength-Dependent Conformational Changes in Collagen after Mid-Infrared Laser Ablation of Cornea

    PubMed Central

    Xiao, Yaowu; Guo, Mingsheng; Zhang, Peng; Shanmugam, Ganesh; Polavarapu, Prasad L.; Hutson, M. Shane

    2008-01-01

    We ablated porcine corneas with a free electron laser tuned to either 2.77 or 6.45 ?m, two matched wavelengths that predominantly target water and protein, respectively. The ejected nonvolatile debris and the crater left behind were examined by circular dichroism, Raman spectroscopy, and scanning electron microscopy to characterize the postablation conformation of collagen proteins. We found near-complete unfolding of collagen secondary and tertiary structure at either ablating wavelength. On the other hand, we found excess fibril swelling and evidence for excess cis-hydroxyproline in the 6.45-?m debris. These results support the hypothesis that the favorable ablative properties of protein-targeting wavelengths rest on selective heating of tissue proteins. PMID:17933877

  6. Laser ablated zirconium plasma: A source of neutral zirconium

    SciTech Connect

    Yadav, Dheerendra; Thareja, Raj K. [Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016, Uttar Pradesh (India)

    2010-10-15

    The authors report spectroscopic investigations of laser produced zirconium (Zr) plasma at moderate laser fluence. At low laser fluence the neutral zirconium species are observed to dominate over the higher species of zirconium. Laser induced fluorescence technique is used to study the velocity distribution of ground state neutral zirconium species. Two-dimensional time-resolved density distributions of ground state zirconium is mapped using planner laser induced fluorescence imaging and total ablated mass of neutral zirconium atoms is estimated. Temporal and spatial evolutions of electron density and temperature are discussed by measuring Stark broadened profile and ratio of intensity of emission lines, respectively.

  7. Aerospace Laser Ignition/Ablation Variable High Precision Thruster

    NASA Technical Reports Server (NTRS)

    Campbell, Jonathan W. (Inventor); Edwards, David L. (Inventor); Campbell, Jason J. (Inventor)

    2015-01-01

    A laser ignition/ablation propulsion system that captures the advantages of both liquid and solid propulsion. A reel system is used to move a propellant tape containing a plurality of propellant material targets through an ignition chamber. When a propellant target is in the ignition chamber, a laser beam from a laser positioned above the ignition chamber strikes the propellant target, igniting the propellant material and resulting in a thrust impulse. The propellant tape is advanced, carrying another propellant target into the ignition chamber. The propellant tape and ignition chamber are designed to ensure that each ignition event is isolated from the remaining propellant targets. Thrust and specific impulse may by precisely controlled by varying the synchronized propellant tape/laser speed. The laser ignition/ablation propulsion system may be scaled for use in small and large applications.

  8. Ultrashort-pulse laser ablation of nanocrystalline aluminum

    SciTech Connect

    Gill-Comeau, Maxime; Lewis, Laurent J. [Departement de Physique et Regroupement Quebecois sur les Materiaux de Pointe (RQMP), Universite de Montreal, C.P. 6128, Succursale Centre-Ville, Montreal, Quebec, H3C 3J7 (Canada)

    2011-12-01

    Molecular-dynamics simulations of the ablation of nanocrystalline Al films by ultrashort laser pulses in the low-fluence (no-ionization) regime (0-2.5 times the ablation threshold, F{sub th}) are reported. The simulations employ an embedded-atom method potential for the dynamics of the ions and a realistic two-temperature model for the electron gas (and its interactions with the ion gas), which confers different electronic properties to the monocrystalline solid, nanocrystalline solid, and liquid regions of the targets. The ablation dynamics in three nanocrystalline structures is studied: two dense targets with different crystallite sizes (d=3.1 and 6.2 nm on average) and a d=6.2 nm porous sample. The results are compared to the ablation of monocrystalline Al. Significant differences are observed, the nanocrystalline targets showing, in particular, a lower ablation threshold and a larger melting depth, and yielding pressure waves of higher amplitude than the monocrystalline targets. Furthermore, it is shown that nanocrystalline targets experience no residual stress associated with thermal expansion and lateral constraints, and that little crystal growth occurs in the solid during and after ablation. Laser-induced spallation of the back surface of the films is also investigated; we find, in particular, that the high-strain fracture resistance of nanocrystalline samples is significantly reduced in comparison to the crystalline material.

  9. Thermal melting and ablation of silicon by femtosecond laser radiation

    NASA Astrophysics Data System (ADS)

    Ionin, A. A.; Kudryashov, S. I.; Seleznev, L. V.; Sinitsyn, D. V.; Bunkin, A. F.; Lednev, V. N.; Pershin, S. M.

    2013-03-01

    The space-time dynamics of thermal melting, subsurface cavitation, spallative ablation, and fragmentation ablation of the silicon surface excited by single IR femtosecond laser pulses is studied by timeresolved optical reflection microscopy. This dynamics is revealed by monitoring picosecond and (sub)nanosecond oscillations of probe pulse reflection, which is modulated by picosecond acoustic reverberations in the dynamically growing surface melt subjected to ablation and having another acoustic impedance, and by optical interference between the probe pulse replicas reflected by the spalled layer surface and the layer retained on the target surface. The acoustic reverberation periods change during the growth and ablation of the surface melt film, which makes it possible to quantitatively estimate the contributions of these processes to the thermal dynamics of the material surface. The results on the thermal dynamics of laser excitation are supported by dynamic measurements of the ablation parameters using noncontact ultrasonic diagnostics, scanning electron microscopy, atomic force microscopy, and optical interference microscopy of the modified regions appearing on the silicon surface after ablation.

  10. Plume dynamics of cross-beam pulsed-laser ablation of graphite

    SciTech Connect

    Sanchez Ake, C.; Sangines de Castro, R.; Sobral, H.; Villagran-Muniz, M. [Laboratorio de Fotofisica, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, Mexico Distrito Federal, 04510 (Mexico)

    2006-09-01

    The dynamics of the interaction between two plasmas induced by cross-beam pulsed-laser ablation was analyzed by time resolved optical emission spectroscopy and fast photography. The plasmas were created in vacuum by irradiating two perpendicular graphite targets with an excimer (248 nm) and a Nd:yttrium-aluminum-garnet (1064 nm) laser. In this configuration, a laser is focused onto a target generating a highly directed plume; subsequently, an additional laser produces a second plasma from the perpendicular target which expands through the first plume. Collisional processes cause a reduction of the kinetic energy of the second plume species as compared to the single pulse experiment. For a fixed delay between lasers of 2 {mu}s, the second plume was divided in two perpendicular directions. The dynamics of this plasma has been compared with laser-induced plume propagation through a background gas in terms of the drag model.

  11. CO{sub 2} Laser Ablation Propulsion Tractor Beams

    SciTech Connect

    Sinko, John E. [Micro-Nano Global Center of Excellence, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan); Schlecht, Clifford A. [Institute for Materials and Complexity, Saint Louis, MO 63112 (United States)

    2010-05-06

    Manipulation of objects at a distance has already been achieved with no small measure of success in the realm of microscopic objects on the scale size of nanometers to micrometers in applications including laser trapping and laser tweezers. However, there has been relatively little effort to apply such remote control to macroscopic systems. A space tractor beam could be applied to a wide range of applications, including removal of orbital debris, facilitation of spacecraft docking, adjustment of satellite attitude or orbital position, etc. In this paper, an ablative laser propulsion tractor beam is demonstrated based on radiation from a CO{sub 2} laser. Cooperative, layered polymer targets were used for remote impulse generation using a CO{sub 2} laser. The use of a structured ablatant enabling switching between thrust directional parity (i.e., forward or reverse) and imparting torque to a remote target. Fluence-dependent results are presented in the context of polymer ablation modeling work and with consideration of confined ablation effects.

  12. Surface quality of excimer laser corneal ablation with different frequencies.

    PubMed

    Liang, F Q; Ishikawa, T; Kim, J; del Cerro, M; Park, S B; Aquavella, J V

    1993-11-01

    To test the effects of different frequencies of a 193-nm excimer laser on the surface smoothness of the ablated materials and the damage to the adjacent structure, four different frequencies (5, 10, 15, and 20 Hz) of a 193-nm excimer laser were used to perform ablations on 20 rabbit corneas and four polymethylmethacrylate blocks at a fluence of 160 mJ/cm2. Each frequency was tested five times on five corneas. The ablated materials were processed and examined with scanning electron microscopy (SEM) and light and transmission electron microscopy (TEM) and a Zygo interference microscope, which quantitatively evaluates the surface smoothness. The results from the Zygo microscope show that there is no statistically significant difference in surface smoothness between any two different frequencies. The SEM reveals similar regularity and uniformity on the ablated surfaces, with no relationship between the laser frequencies and the amount of surface deposits. The TEM demonstrates no correlation between the various frequencies and the thickness of the superficial pseudomembrane and the amount of collateral damage in the adjacent stroma. It appears that the higher frequencies are comparable to the lower one (5 Hz) as to ablation quality, with the benefit of curtailing surgical time and decreasing the chances of eye movement. PMID:8261781

  13. Cluster Generation Under Pulsed Laser Ablation Of Compound Semiconductors

    SciTech Connect

    Bulgakov, Alexander V.; Evtushenko, Anton B.; Shukhov, Yuri G. [Institute of Thermophysics SB RAS, Lavrentyev Ave. 1, 630090 Novosibirsk (Russian Federation); Ozerov, Igor; Marine, Wladimir [Universite de la Mediterranee, CINaM, UPR CNRS 3118, 13288 Marseille (France)

    2010-10-08

    A comparative experimental study of pulsed laser ablation in vacuum of two binary semiconductors, zinc oxide and indium phosphide, has been performed using IR- and visible laser pulses with particular attention to cluster generation. Neutral and cationic Zn{sub n}O{sub m} and In{sub n}P{sub m} particles of various stoichiometry have been produced and investigated by time-of-flight mass spectrometry. At ZnO ablation, large cationic (n>9) and all neutral clusters are mainly stoichiometric in the ablation plume. In contrast, indium phosphide clusters are strongly indium-rich with In{sub 4}P being a magic cluster. Analysis of the plume composition upon laser exposure has revealed congruent vaporization of ZnO and a disproportionate loss of phosphorus by the irradiated InP surface. Plume expansion conditions under ZnO ablation are shown to be favorable for stoichiometric cluster formation. A delayed vaporization of phosphorus under InP ablation has been observed that results in generation of off-stoichiometric clusters.

  14. Laser-Energy Coupling, Mass Ablation Rate, and Shock-Heating in Direct-Drive ICF

    NASA Astrophysics Data System (ADS)

    Regan, S. P.

    2006-10-01

    Direct-drive laser-energy coupling, mass ablation rate, and shock-heating are experimentally studied on the OMEGA Laser System to validate hydrodynamics simulations. High-gain, direct-drive inertial confinement fusion (ICF) target implosions require accurate predictions of the shell adiabat ? (entropy), defined as the pressure in the main fuel layer to the Fermi-degenerate pressure. Since the minimum energy for ignition scales as Emin˜ ?^1.9 and the Rayleigh--Taylor ablative stabilization term is proportional to the ablation velocity Va˜ ?^3/5; a balance must be struck. The temporal pulse shape of the laser irradiation determines the adiabat. A series of experiments in spherical and planar geometries with CH targets have measured the laser absorption, mass ablation rate, and the amount of shock heating in the target. Time-resolved measurements of laser absorption in the corona are performed on spherical implosion experiments. The mass ablation rate is inferred from time-resolved Ti K-shell spectroscopic measurements of nonaccelerating, solid CH spherical targets with a buried tracer layer of Ti. The amount of shock heating is diagnosed in planar-CH-foil targets using two techniques: time-resolved x-ray absorption spectroscopy and noncollective spectrally resolved x-ray scattering. The predicted shell conditions are close to the experimental results. A detailed comparison of the experimental results and the simulations will be presented. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460. Contributors: H. Sawada, D. Li, V. N. Goncharov, R. Epstein, J. A. Delettrez, J. P. Knauer, J. A. Marozas, F. J. Marshall, R. L. McCrory, P. W. McKenty, D. D. Meyerhofer, P. B. Radha, W. Seka, T. C. Sangster, S. Skupsky, V. A. Smalyuk, LLE/UR, R. Mancini, University of Nevada, S.H. Glenzer, O. Landen LLNL, G. Gregori, RAL

  15. Effect of intensity clamping on laser ablation by intense femtosecond laser pulses.

    PubMed

    Xu, Z J; Liu, W; Zhang, N; Wang, M W; Zhu, X N

    2008-03-17

    We have experimentally demonstrated that because of intensity clamping, when the laser peak power is higher than the critical power for self-focusing, further increase of the laser power cannot result in corresponding increase of the laser ablation rate of a metallic sample placed in gases. The ablation rate will finally approach a stabilized value. Also, the experimental technique implemented in our work could be potentially used to measure the self-focusing critical power and the nonlinear refractive index. PMID:18542453

  16. Laser ablative surface treatment for enhanced bonding of Ti-6Al-4V alloy.

    PubMed

    Palmieri, Frank L; Watson, Kent A; Morales, Guillermo; Williams, Thomas; Hicks, Robert; Wohl, Christopher J; Hopkins, John W; Connell, John W

    2013-02-01

    Adhesive bonding offers many advantages over mechanical fastening, but requires certification before it can be incorporated in primary structures for commercial aviation without disbond-arrestment features or redundant load paths. Surface preparation is widely recognized as the key step to producing robust and predictable adhesive bonds. Surface preparation by laser ablation provides an alternative to the expensive, hazardous, polluting, and less precise practices used currently such as chemical-dip, manual abrasion and grit blast. This report documents preliminary testing of a surface preparation technique using laser ablation as a replacement for the chemical etch and abrasive processes currently applied to Ti-6Al-4V alloy adherends. Surface roughness and surface chemical composition were characterized using interference microscopy and X-ray photoelectron spectroscopy, respectively. A technique for fluorescence visualization was developed which allowed for quantitative failure mode analysis. Wedge crack extension testing in a hot, humid environment indicated the relative effectiveness of various surface treatments. Increasing ablation duty cycle reduced crack propagation and adhesive failure. Single lap shear testing showed an increase in strength and durability as laser ablation duty cycle and power were increased. Chemical analyses showed trends for surface chemical species, which correlated with improved bond strength and durability. PMID:23317556

  17. Temperature dependent ablation threshold in silicon using ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Thorstensen, Jostein; Erik Foss, Sean

    2012-11-01

    We have experimentally investigated the ablation threshold in silicon as a function of temperature when applying ultrashort laser pulses at three wavelengths. By varying the temperature of a silicon substrate from room temperature to 320 °C, we observe that the ablation threshold for a 3 ps pulse using a wavelength of 1030 nm drops from 0.43 J/cm2 to 0.24 J/cm2, a reduction of 43%. For a wavelength of 515 nm, the ablation threshold drops from 0.22 J/cm2 to 0.15 J/cm2, a reduction of 35%. The observed ablation threshold for pulses at 343 nm remains constant with temperature, at 0.10 J/cm2. These results indicate that substrate heating is a useful technique for lowering the ablation threshold in industrial silicon processing using ultrashort laser pulses in the IR or visible wavelength range. In order to investigate and explain the observed trends, we apply the two-temperature model, a thermodynamic model for investigation of the interaction between silicon and ultrashort laser pulses. Applying the two-temperature model implies thermal equilibrium between optical and acoustic phonons. On the time scales encountered herein, this need not be the case. However, as discussed in the article, the two-temperature model provides valuable insight into the physical processes governing the interaction between the laser light and the silicon. The simulations indicate that ablation occurs when the number density of excited electrons reaches the critical electron density, while the lattice remains well below vaporization temperature. The simulated laser fluence required to reach critical electron density is also found to be temperature dependent. The dominant contributor to increased electron density is, in the majority of the investigated cases, the linear absorption coefficient. Two-photon absorption and impact ionization also generate carriers, but to a lesser extent. As the linear absorption coefficient is temperature dependent, we find that the simulated reduction in ablation threshold with increased substrate temperature is linked to the temperature dependence of the linear absorption coefficient. Another factor influencing the ablation threshold is the wavelength dependence of the interaction with the excited electron plasma. This wavelength dependence can explain that we observe experimentally similar ablation thresholds for a wavelength of 1030 nm at 320 °C and for 515 nm at room temperature, even though the linear absorption coefficient in the latter case is much higher.

  18. Endometrial laser ablation in rabbits: A comparative study of three laser types

    SciTech Connect

    Rosenberg, C.; Tadir, Y.; Braslavsky, D.; Fisch, B.; Karni, Z.; Ovadia, J. (Beilinson Medical Center, Tel Aviv (Israel))

    1990-01-01

    Endometrial laser ablation is one of the alternatives to hysterectomy in cases of intractable uterine bleeding. It is currently performed using the Nd:YAG laser at 1.06 microns. The aim of this study was to compare the tissue effect of three types of laser irradiation (Nd:YAG laser at 1.06 and 1.32 microns and holmium laser at 2.12 microns) on the rabbit endometrium. Crater formation, coagulation necrosis, and muscle necrosis were evaluated at the time of ablation, as well as at 1 week and 4 weeks postablation. The results were assessed by determining the depth and width of the affected portion in the uterine wall (lumen to serosa). It was shown that Nd:YAG laser at 1.32 microns caused more generalized and extended effects as compared with the other laser types examined. Endometrial regeneration was faster after ablation by the Nd:YAG laser at 1.06 microns and the holmium laser than by the Nd:YAG laser at 1.32 microns. The widest range of ablation energy (defined as that causing ablation without muscle damage) was achieved by applying the holmium laser. Further evaluation of the holmium laser for this indication is recommended.

  19. Effect of sampling geometry on elemental emissions in laser-induced breakdown spectroscopy

    Microsoft Academic Search

    Rosalie A. Multari; Leeann E. Foster; David A. Cremers; Monty J. Ferris

    1996-01-01

    In laser-induced breakdown spectroscopy (LIBS), a focused laser pulse is used to ablate material from a surface and form a laser plasma that excites the vaporized material. Geometric factors, such as the distance between the sample and the focusing lens and the method of collecting the plasma light, can greatly influence the analytical results. To obtain the best quantitative results,

  20. Laser ablation in a liquid-confined environment using a nanosecond laser pulse

    SciTech Connect

    Kang, Hyun Wook [American Medical Systems, Minnetonka, Minnesota 55343 (United States); Lee, Ho [School of Mechanical Engineering, Kyungpook National University, Dae-gu 702-701 (Korea, Republic of); Welch, Ashley J. [Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas 78712 (United States)

    2008-04-15

    Laser ablation of aluminum metal with 1 ns, 800 nm pulse at low radiant exposures was investigated in air (dry) and water (wet) environments. Compared to dry ablation, an approximately eight times increase in material removal rate was associated with wet ablation. Based on optical reflectance and scanning electron microscope images, bubble formation/collapse was responsible for augmented acoustic pressure and ablation performance. Numerically simulated temperature distributions during wet ablation were consistent with the occurrence of explosive water vaporization near the critical temperature of water. Strong pressure emission during liquid vaporization and jet formation can account for enhanced ablation process. Radial expansion of bubbles minimized the redeposition of debris, leading to improvements in energy coupling to the target and ablation performance.

  1. Spin-offs from laser ablation in art conservation

    NASA Astrophysics Data System (ADS)

    Asmus, J.; Elford, J.; Parfenov, V.

    2013-05-01

    In 1973 The Center for Art Conservation Studies (CASS) was established at the University of California, San Diego (UCSD). This was in response to demonstrations that were conducted during January-March 1972 in Venice for UNESCO, Venice in Peril, International Fund for Monuments, and the Italian Petroleum Institute (ENI). The feasibility investigation explored in-situ pulsed holography, holographic interferometry, and laser ablation divestment for applications in art conservation practice. During subsequent decades scores of UCSD graduate and undergraduate students as well as conservators, conservation scientists, academics, and engineers who resided in CASS as "Visiting Scholars" contributed to advancing the understanding and performance of radiation technologies in the arts. Several technologies in addition to those involving optical wavelengths were also investigated to aid in art conservation and conservation science. Magnetic Resonance Imaging (MRI) and Nuclear Magnetic Resonance (NMR) were employed to detect and map moisture within masonry. Lead isotopic analyses revealed authenticity and provenance of Benin bronzes. Inside-out x-ray radiography facilitated the detection of defects in stone. Ultrasonic imaging was introduced for the mapping of fresco strata. Photoacoustic Spectroscopy (PAS) was used to characterize varnish layers on paintings. Digital image processing was introduced in order to detect and visualize pentimenti within paintings as well as to perform virtual restoration and provide interactive museum displays. Holographic images were employed as imaginary theater sets. In the years that followed the graduation of students and the visits of professional collaborators, numerous other applications of radiation ablation began appearing in a wide variety of other fields such as aircraft maintenance, ship maintenance, toxic chemical remediation, biological sterilization, food processing, industrial fabrication, industrial maintenance, nuclear decontamination, dermatology, nuclear weapons effects simulation, and graffiti control. It was readily apparent that the customary diffusion of advanced technologies from science and industry into the art conservation field had been reversed. In this paper we trace the migration and adaptation of radiation divestment developments in art conservation to numerous applications in science, industry, and consumer products. Examples described include the robotized hybrid "Flashjet" aircraft paint stripping system, the "Novotronic" anthrax remediation installation in the Pentagon Building, the InTa automated graffiti removal system employing a carbon dioxide TEA laser, the Bellalite body hair removal product incorporating flashlamp technology, and the Foodco line of optical radiation products for the sterilization of food products. The Foodco products are also applied to the sterilization and/or pasteurization of beverages and beverage containers. A similar device has been adapted to seafood irradiation in order to increase shelf life, as well as for the ablative removal of skin and scales. The Goodyear Tire and Rubber Company, to etch logos and identification information into the sidewalls of pneumatic tires, also developed a flashlamp-based ablation technology. The founders of the CYMER Corporation applied UV irradiation technology to the manufacture of high-performance integrated circuits (viz., memory chips, etc.) In several instances former CASS students and Visiting Fellows consciously adapted the above-learned art conservation methodologies to still other purposes. Thus, these examples of technology transfer may be termed: "Art in the service of Science." Alternatively, it is evident that many associated innovations developed from independent activities, unconnected serendipity, or through the normal diffusion of information and knowledge across disciplines.

  2. Nanosecond and femtosecond laser spectroscopy of molecules of biological interest

    NASA Astrophysics Data System (ADS)

    Villani, P.; Orlando, S.; Santagata, A.; De Bonis, A.; Veronesi, S.; Giardini, A.

    2007-07-01

    This paper mainly concerns on nanosecond and femtosecond laser spectroscopy of aromatic organic compounds as neurotransmitters, and plume diagnostics of the ablated species, in order to characterize the plasma dynamics, i.e. the temporal and spatial evolution of the plume. Optical emission spectroscopy has been applied to characterize the transient species produced in the femtosecond (fs) and nanosecond (ns) regimes. The laser sources employed for optical emission spectroscopy are a frequency-doubled Nd:YAG Handy ( ? = 532 nm, ? = 5 ns) and a frequency-doubled Nd:glass ( ? = 527 nm, ? = 250 fs). These studies aim to detect and give information on the photoexcitation and photodissociation of these biological molecules and to compare the plasma characteristics in the two ablation regimes.

  3. Laser Ablation ICPMS Laboratory Department of Geosciences Virginia Tech

    E-print Network

    Bodnar, Robert J.

    Laser Ablation ICPMS Laboratory Department of Geosciences ­ Virginia Tech Facility Rates (Approved for Virginia Tech Faculty, Staff and Students properly trained. We are not allowed to offer those rates to people not affiliated with Virginia Tech; 2) Internal rates are available only for Virginia Tech users; 3

  4. Perfluorocarbon compounds: transmitting liquids for infrared laser tissue ablation

    NASA Astrophysics Data System (ADS)

    Frenz, Martin; Pratisto, Hans S.; Toth, Cynthia A.; Jansen, E. Duco; Altermatt, Hans J.; Welch, Ashley J.; Weber, Heinz P.

    1996-05-01

    One concern during IR-laser ablation of tissue under water is the mechanical injury that may be induced in tissue due to rapid bubble expansion and collapse or due to strong laser-induced pressure waves. The objective of this study was to evaluate the feasibility of using a liquid which is transparent to the IR-region of the spectrum in order to minimize these undesired mechanical side-effects. As transmitting medium perfluorocarbon liquid was used. Free- running Er:YAG and Ho:YAG laser pulses were delivered into the liquid via a 400 micrometers fiber. Bubble formation during the ablation process was recorded with fast flash photography while pressure transients were measured with a needle hydrophone. The effect of the surrounding material (air, water, perfluorooctane) on the tissue response of chicken breast was evaluated in vitro using histology. It was observed that a large bubble (up to 6 mm in diameter) was formed under perfluorooctane driven by the ablation products. This bubble, however, does not generate a pressure wave when collapsing. Although perfluorooctane only shows a weak absorption for infrared radiation, laser-induced thermal lensing in the liquid strongly decreases the radiant exposure and therefore the ablation efficiency.

  5. Particle Generation by Ultraviolet-Laser Ablation during Surface Decontamination

    Microsoft Academic Search

    Doh-Won Lee; Meng-Dawn Cheng

    2006-01-01

    A novel photonic decontamination method was developed for removal of pollutants from material surfaces. Such a method relies on the ability of a high-energy laser beam to ablate materials from a contaminated surface layer, thus producing airborne particles. In this paper, the authors presented the results obtained using a scanning mobility particle sizer (SMPS) system and an aerosol particle sizer

  6. Polymers designed for laser ablation-inuence of photochemical properties

    E-print Network

    Dickinson, J. Thomas

    Polymers designed for laser ablation-in¯uence of photochemical properties T. Lipperta,* , J as 25 mJ cmÀ2 ) and the highest etch rates (up to 3 mm/pulse), followed by the designed polyesters mechanisms range from thermal, over photothermal to photochemical [10±12]. In recent publications

  7. Laser ablation assisted adhesive bonding of automotive structural composites

    SciTech Connect

    Boeman, R.G.; Paulauskas, F.L.; Warren, C.D.

    1999-07-03

    Laser ablation has been evaluated as a surface pretreatment prior to adhesive bonding. In prior experimental work, it was observed that when adhesively bonded, composite, single lap shear samples fail, the fracture often occurs at either the adhesive/adherend interface or in the resin rich surface layer of the composite. These two areas represent the weakest portion of the joint. Laser ablation pretreatment generates areas where the resin on the composite surface is selectively removed leaving behind exposed reinforcing fibers which are the major load bearing members of the composite. In a subsequent adhesive bonding operation, this allows portions of the fibers to be encapsulated in the adhesive while other portions of the fiber remain in the composite resin. This type of pretreatment permits fibers to bridge and reinforce the interface between adhesive and adherend. A secondary benefit is the removal of surface contaminantes by pyrolysis. Microscopic observation of laser ablated surfaces indicates a prominent, fiber rich area. Results of the mechanical evaluation indicated that the lap shear strength for laser ablated samples was significantly higher than specimens with no pretreatment or with solvent cleaning only, but were slightly lower than specimens that were mechanically roughened and cleaned with solvents prior to bonding.

  8. Ablation by ultrashort laser pulses: Atomistic and thermodynamic analysis of the processes at the ablation threshold

    SciTech Connect

    Upadhyay, Arun K. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Inogamov, Nail A. [Landau Institute for Theoretical Physics, Russian Academy of Science, Kosygina 2, 117940 Moscow (Russian Federation); Rethfeld, Baerbel; Urbassek, Herbert M. [Fachbereich Physik, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany)

    2008-07-15

    Ultrafast laser irradiation of solids may ablate material off the surface. We study this process for thin films using molecular-dynamics simulation and thermodynamic analysis. Both metals and Lennard-Jones (LJ) materials are studied. We find that despite the large difference in thermodynamical properties between these two classes of materials--e.g., for aluminum versus LJ the ratio T{sub c}/T{sub tr} of critical to triple-point temperature differs by more than a factor of 4--the values of the ablation threshold energy E{sub abl} normalized to the cohesion energy, {epsilon}{sub abl}=E{sub abl}/E{sub coh}, are surprisingly universal: all are near 0.3 with {+-}30% scattering. The difference in the ratio T{sub c}/T{sub tr} means that for metals the melting threshold {epsilon}{sub m} is low, {epsilon}{sub m}<{epsilon}{sub abl}, while for LJ it is high, {epsilon}{sub m}>{epsilon}{sub abl}. This thermodynamical consideration gives a simple explanation for the difference between metals and LJ. It explains why despite the universality in {epsilon}{sub abl}, metals thermomechanically ablate always from the liquid state. This is opposite to LJ materials, which (near threshold) ablate from the solid state. Furthermore, we find that immediately below the ablation threshold, the formation of large voids (cavitation) in the irradiated material leads to a strong temporary expansion on a very slow time scale. This feature is easily distinguished from the acoustic oscillations governing the material response at smaller intensities, on the one hand, and the ablation occurring at larger intensities, on the other hand. This finding allows us to explain the puzzle of huge surface excursions found in experiments at near-threshold laser irradiation.

  9. Preparation and characterization of bismuth nanostructures deposited by pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Escobar-Alarcón, L.; Morales-Mendez, J. G.; Solís-Casados, D. A.; Romero, S.; Fernández, M.; Haro-Poniatowski, E.

    2015-01-01

    Bismuth nanostructures, from nanoparticles to quasi-percolated films, were deposited by pulsed laser ablation (PLA) on different substrates using the 355 nm line of a Nd:YAG laser. The morphology and size distribution of the obtained nanostructures were investigated, as a function of the number of ablation pulses, by high resolution electron microscopy (HRTEM) and atomic force microscopy (AFM). Deposits with a small number of pulses, 50, are formed of separated isolated particles with diameters in the range from 5 to 20 nm. Further increase in the number of pulses (>100) results in coalescence of individual particles with the formation of dendritic structures and finally, for 500 pulses, quasi-percolated Bi films are obtained. Additionally, the nanostructures formed were characterized by XPS, and Raman spectroscopy in order to determine the physical and chemical properties of the deposited material.

  10. Pulsed laser ablation plasmas generated in CO{sub 2} under high-pressure conditions up to supercritical fluid

    SciTech Connect

    Kato, Toru; Stauss, Sven; Kato, Satoshi; Urabe, Keiichiro; Terashima, Kazuo [Department of Advanced Materials Science, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Baba, Motoyoshi; Suemoto, Tohru [Division of Advanced Spectroscopy, Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

    2012-11-26

    Pulsed laser ablation of solids in supercritical media has a large potential for nanomaterials fabrication. We investigated plasmas generated by pulsed laser ablation of Ni targets in CO{sub 2} at pressures ranging from 0.1 to 16 MPa at 304.5 K. Plasma species were characterized by optical emission spectroscopy, and the evolution of cavitation bubbles and shockwaves were observed by time-resolved shadowgraph imaging. Ni and O atomic emissions decreased with increasing gas pressure; however, near the critical point the intensities reached local maxima, probably due to the enhancement of the plasma excitation and effective quenching resulting from the large density fluctuation.

  11. Surfactant-free small Ni nanoparticles trapped on silica nanoparticles prepared by pulsed laser ablation in liquid

    NASA Astrophysics Data System (ADS)

    Mafuné, Fumitaka; Okamoto, Takumi; Ito, Miho

    2014-01-01

    Small Ni nanoparticles supported on silica nanoparticles were formed by pulsed laser ablation in liquid. Water dispersing surfactant-free silica particles was used here as a solvent, and a bulk Ni metal plate as a target. The nanoparticles formed by laser ablation in water were readily stabilized by the silica particles, whereas Ni nanoparticles prepared in water without silica were found to be precipitated a few hours after aggregation into 5-30 nm particles. The nanoparticles were characterized by TEM, dark-field STEM and optical absorption spectroscopy, which indicated that small 1-3 nm Ni nanoparticles were adsorbed on the surface of silica.

  12. Determining Optimum Propellants, Pulse Lengths, and Laser Intensity for Ablative Laser Propulsion Using the Pals Laser

    Microsoft Academic Search

    Frederick P. Boody

    2004-01-01

    Ablative Laser Propulsion (ALP) can potentially reduce the cost of launching payloads into near earth orbit by a factor of 100. Preliminary experiments have demonstrated high efficiency, coupling coefficient, and specific impulse that would be suitable for applications. These experiments, however, were performed at wavelengths not usable in the atmosphere and at pulse energies and spot sizes much smaller than

  13. Recent advances in laser ablation modelling for asteroid deflection methods

    NASA Astrophysics Data System (ADS)

    Thiry, Nicolas; Vasile, Massimiliano

    2014-09-01

    Over the past few years, a series of studies have demonstrated the theoretical benefits of using laser ablation in order to mitigate the threat of a potential asteroid on a collision course with earth. Compared to other slow-push mitigation strategies, laser ablation allows for a significant reduction in fuel consumption since the ablated material is used as propellant. A precise modelling of the ablation process is however difficult due to the high variability in the physical parameters encountered among the different asteroids as well as the scarcity of experimental studies available in the literature. In this paper, we derive a new thermal model to simulate the efficiency of a laser-based detector. The useful material properties are first derived from thermochemical tables and equilibrium thermodynamic considerations. These properties are then injected in a 3D axisymetrical thermal model developed in Matlab. A temperature-dependent conduction flux is imposed on the exterior boundary condition that takes into account the balance between the incident power and the power losses due to the vaporization process across the Knudsen layer and the radiations respectively. A non-linear solver is finally used and the solution integrated over the ablation front to reconstruct the net thrust and the global mass flow. Compared to an initial 1D model, this new approach shows the importance of the parietal radiation losses in the case of a CW laser. Despite the low energy conversion efficiency, this new model still demonstrates the theoretical benefit of using lasers over more conventional low-thrust strategies.

  14. Laser optogalvanic spectroscopy of molecules

    NASA Technical Reports Server (NTRS)

    Webster, C. R.; Rettner, C. T.

    1983-01-01

    In laser optogalvanic (LOG) spectroscopy, a tunable laser is used to probe the spectral characteristics of atomic or molecular species within an electrical discharge in a low pressure gas. Optogalvanic signals arise when the impedance of the discharge changes in response to the absorption of laser radiation. The technique may, therefore, be referred to as impedance spectroscopy. This change in impedance may be monitored as a change in the voltage across the discharge tube. LOG spectra are recorded by scanning the wavelength of a chopped CW dye laser while monitoring the discharge voltage with a lock-in amplifier. LOG signals are obtained if the laser wavelength matches a transition in a species present in the discharge (or flame), and if the absorption of energy in the laser beam alters the impedance of the discharge. Infrared LOG spectroscopy of molecules has been demonstrated and may prove to be the most productive application in the field of optogalvanic techniques.

  15. Momentum transfer in laser-induced ablation of hard tissue measured by laser Doppler vibrometry

    NASA Astrophysics Data System (ADS)

    Foth, Hans-Jochen; Barton, Thomas G.; Meyer, Dirk H.; Postel, Adriaen

    1998-07-01

    A laser Doppler vibrometer was used in a pendulum experiment to measure the recoil momentum induced in hard tissue by pulsed infrared laser exposure. A Holmium:YAG laser was irradiated at bone and a superpulsed CO2 laser irradiated at dentin. Since the masses of the samples were known and the ablated masses were measured, this method allowed an indirect determination of the velocity of the ablated particles. In a second experiment performed with the CO2 laser the velocities of the ablated particles were measured directly by the time of flight detected by the laser beam of the vibrometer. The results of both methods are in good agreement; at a mean power of 0.5 Watt of the CO2 laser the velocity was 50 - 60 m/s increasing at higher mean powers.

  16. Pulsed laser ablation of Germanium under vacuum and hydrogen environments at various fluences

    NASA Astrophysics Data System (ADS)

    Iqbal, Muhammad Hassan; Bashir, Shazia; Rafique, Muhammad Shahid; Dawood, Asadullah; Akram, Mahreen; Mahmood, Khaliq; Hayat, Asma; Ahmad, Riaz; Hussain, Tousif; Mahmood, Arshad

    2015-07-01

    Laser fluence and ambient environment play a significant role for the formation and development of the micro/nano-structures on the laser irradiated targets. Single crystal (1 0 0) Germanium (Ge) has been ablated under two environments of vacuum (10-3 Torr) and hydrogen (100 Torr) at various fluences ranging from 4.5 J cm-2 to 6 J cm-2. For this purpose KrF Excimer laser with wavelength of 248 nm, pulse duration of 18 ns and repetition rate of 20 Hz has been employed. Surface morphology has been observed by Scanning Electron Microscope (SEM). Whereas, structural modification of irradiated targets was explored by Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. Electrical conductivity of the irradiated Ge is measured by four probe method. SEM analysis exhibits the formation of laser-induced periodic surface structures (LIPSS), cones and micro-bumps in both ambient environments (vacuum and hydrogen). The formation as well as development of these structures is strongly dependent upon the laser fluence and environmental conditions. The periodicity of LIPSS or ripples varies from 38 ?m to 60 ?m in case of vacuum whereas in case of hydrogen environment, the periodicity varies from 20 ?m to 45 ?m. The difference in number of ripples and periodicity as well as in shape and size of cones and bumps in vacuum and hydrogen is explained on the basis of confinement and shielding effect of plasma. FTIR spectroscopy reveals that no new bands are formed for laser ablated Ge under vacuum, whereas Csbnd H stretching vibration band is formed for two moderate fluences (5 J cm-2 and 5.5 J cm-2) in case of ablation in hydrogen. Raman spectroscopy shows that no new bands are formed in case of ablation in both environments; however a slight Raman shift is observed which is attributed to laser-induced stresses. The electrical conductivity of the irradiated Ge increases with increasing fluence and is also dependent upon the environment as well as grown structures.

  17. Comparison of ablation stake measurements and Airborne Laser Scanning results

    NASA Astrophysics Data System (ADS)

    Rieg, Lorenzo; Galos, Stephan; Klug, Christoph; Sailer, Rudolf

    2014-05-01

    Ablation measurements using ablation stakes are a well-established method in glaciology, which sees a lot of use. However, ablation stakes cannot always be installed and read at a sufficient number of points on a glacier or on multiple glaciers, due to limited personnel and financial capacities or because of inaccessible areas due to dangerous zones (crevasses, rock falls, avalanches) or remote terrain. Furthermore, ablation stakes only enable measurements of surface melt, whereas basal or internal melt processes as well as surface change related to glacier dynamics cannot be measured. Multi temporal Airborne laser scanning (ALS) can provide high resolution and very accurate topographic information for the whole glacier area, which allows the calculation of the difference in surface height and therefore - if the density profile is known or can be estimated - the determination of the local mass balance, including processes like basal melt at least to a certain degree. To gain a better understanding of the differences between ablation stake readings and differential ALS data at the stake locations, the results of both methods have been compared in detail. At Langenferner, a glacier in the Italian Eastern Alps, where mass balance measurements have been carried out since 2004, three ALS campaigns have been conducted at the end of the hydrological year in 2005, 2010 and 2013. There are about 30 ablation stakes installed at the glacier, which have been read during or very close to the time of the flight campaigns. The ablation measurements are then compared to the surface differences calculated from ALS data at the locations of the ablation stakes. To take the movement of the stakes due to glacier dyanmics into account, the position of the stakes has been measured with a differential GPS.

  18. Correlation of laser ablation plasma emission with ICP-AES signal intensity

    SciTech Connect

    Fernandez, A.J.; Mao, X.L.; Shannon, M.A. [Lawrence Berkeley Lab., CA (United States)] [and others

    1994-12-31

    Laser ablation offers many favorable characteristics for direct solid sample chemical analysis. However, the technique usually provides poor precision in comparison to solution nebulization. The primary contributor to this imprecision is the irreproducibility of the laser material interaction. This paper describes a technique for monitoring changes in the laser material interaction directly, and using these data to improve inductively coupled atomic emission spectroscopy (ICP-AES). Simultaneous measurements of the spectral emission intensity in the laser-induced plasma (LIP) and the ICP-AES were made under different power density conditions. The LIP spatial profile and excitation temperature was measured. The data from the LIP show a strong correlation with ICP-AES signal intensity. Both emission signals increase linearly with the laser power density (log-log) and show a change in the slope for different spot sizes and laser powers. These results support the occurrence of two different ablation mechanisms, a less efficient interaction dominating at the higher power densities (> 1 GW/cm2) and a more efficient interaction in the lower power density regimes. The benefits of using simultaneous monitoring of the laser induced plasma for chemical analysis by ICP-AES will be discussed.

  19. Acoustic transients following excimer laser ablation of the cornea.

    PubMed

    Gobbi, P G; Carones, F; Brancato, R; Pini, R; Siano, S

    1995-01-01

    Pressure transients occurring inside the eyeball as a consequence of excimer laser ablation of the cornea were measured at various distances along the optical axis, on enucleated porcine eyes. Positive (compressive) pressure spikes up to 90 bars were observed, lasting 100 ns, and developing, as they propagated in the eyeball, satellite rarefaction pulses with negative pressure as high as -40 bar. Such rarefaction wavefronts can trigger the formation of cavitation bubbles, in both the anterior and posterior chamber, depending on the ablation geometry. The potential risks associated with these photoacoustic phenomena, particularly for retina and corneal endothelium, are outlined. PMID:8963167

  20. Ablation of Submicrometer Holes Using an Extreme-Ultraviolet Laser

    NASA Astrophysics Data System (ADS)

    Rossall, Andrew K.; Aslanyan, Valentin; Tallents, Greg J.; Kuznetsov, Ilya; Rocca, Jorge J.; Menoni, Carmen S.

    2015-06-01

    Simulations and experiments are used to study extreme-ultraviolet (EUV) laser drilling of submicrometer holes. The ablation process is studied with a 2D Eulerian hydrodynamic code that includes bound-free absorption processes relevant to the interaction of EUV lasers with a solid material. Good agreement is observed between the simulated and measured ablated depths for on-target irradiances of up to 1×10 10 W cm-2 . An increase in the irradiance to 1×10 12 W cm-2 is predicted to ablate material to a depth of 3.8 ? m from a single pulse with a hole diameter 3 to 4 times larger than the focal spot size. The model allows for the simulation of the interaction of a laser pulse with the crater created by a previous shot. Multiple-pulse lower-fluence irradiation configurations under optimized focusing conditions, i.e., approaching the diffraction limit, are shown to be advantageous for applications requiring mesoscale [(100 nm )- (1 ? m ) ] features and a high level of control over the ablation profile.

  1. Synthesis efficiency of heavy carbon clusters from ETFE ablated by different numbers of laser pulse in vacuum

    Microsoft Academic Search

    K. Shibagaki; N. Takada; K. Sasaki; K. Kadota

    2002-01-01

    We have carried out mass spectral analysis of positive ions produced by laser ablation of a copolymer of ethylene and tetrafluoroethylene (ETFE: [?CH2?CH2?CF2?CF2?]n) in vacuum using time-of-flight mass spectrometry (TOF-MS). The surfaces of the ETFE targets irradiated by different numbers of laser pulse were analyzed by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Heavy carbon cluster ions Cn+

  2. Protein structural failure in mid-IR laser ablation of cornea

    NASA Astrophysics Data System (ADS)

    Hutson, M. Shane; Xiao, Yaowu; Guo, Mingsheng

    2006-05-01

    Researchers have previously observed that tissue ablation with a free electron laser tuned to wavelengths between 6-7 ?m is accompanied by remarkably little collateral damage. Attempts to explain these observations have invoked a wavelength-dependent loss of protein structural integrity; however, the molecular nature of this structural failure has been heretofore ill-defined. In this report, we evaluate several candidates for the relevant transition by analyzing the non-volatile debris ejected during ablation. Porcine corneas were ablated with a free electron laser tuned to either 2.77 or 6.45 ?m - wavelengths that are equally well absorbed by hydrated corneas, but that respectively target water or protein as the primary chromophore. The ejected debris was characterized via gel electrophoresis, as well as FTIR, micro-Raman and 13C-NMR spectroscopy. We find that high-fluence (240 J/cm2) ablation at 6.45 ?m, but not at 2.77 ?m, leads to protein fragmentation. This fragmentation is accompanied by the accumulation of nitrile and alkyne species. Although these initial experiments did not detect significant protein unfolding, the loss of collagen triple-helix structure was evident using UV and vibrational circular dichroism. The candidate transition most consistent with all these observations is scission of the collagen protein backbone at N-alkylamide bonds. Identifying this transition is a key step towards understanding the observed wavelength-dependence of collateral damage.

  3. Higher Order Chemistry Models in the CFD Simulation of Laser-Ablated Carbon Plumes

    NASA Technical Reports Server (NTRS)

    Greendyke, R. B.; Creel, J. R.; Payne, B. T.; Scott, C. D.

    2005-01-01

    Production of single-walled carbon nanotubes (SWNT) has taken place for a number of years and by a variety of methods such as laser ablation, chemical vapor deposition, and arc-jet ablation. Yet, little is actually understood about the exact chemical kinetics and processes that occur in SWNT formation. In recent time, NASA Johnson Space Center has devoted a considerable effort to the experimental evaluation of the laser ablation production process for SWNT originally developed at Rice University. To fully understand the nature of the laser ablation process it is necessary to understand the development of the carbon plume dynamics within the laser ablation oven. The present work is a continuation of previous studies into the efforts to model plume dynamics using computational fluid dynamics (CFD). The ultimate goal of the work is to improve understanding of the laser ablation process, and through that improved understanding, refine the laser ablation production of SWNT.

  4. A Proton Source via Laser Ablation of Hydrogenated Targets

    NASA Astrophysics Data System (ADS)

    Delle Side, D.; Nassisi, V.; Velardi, L.

    2014-04-01

    In this work we present results on the extraction of proton beams from a plasma generated by pulsed laser ablation of solid hydrogenated targets. The laser used was an excimer KrF operating at low irradiances (108-109 W/cm2) and nanosecond pulse duration. The ablated targets were disks obtained by compression of TiH2 powder. The ion emission was analyzed by the time-of-flight technique using a Faraday cup as ion collector. In order to improve the ion yield, an electrostatic extraction system was applied. Studies on the produced plasma for different laser irradiances and accelerating voltages have been performed. The results obtained show that this setup is suitable for a high yield proton source.

  5. Thrust Measurements in Ballistic Pendulum Ablative Laser Propulsion Experiments

    SciTech Connect

    Brazolin, H. [Instituto Tecnologico de Aeronautica 12.228-900-Sao Jose dos Campos (Brazil); Rodrigues, N. A. S.; Minucci, M. A. S. [Instituto de Estudos Avancados 12.228-001-Sao Jose dos Campos (Brazil)

    2008-04-28

    This paper describes a setup for thrust measurement in ablative laser propulsion experiments, based on a simple ballistic pendulum associated to an imaging system, which is being assembled at IEAv. A light aluminium pendulum holding samples is placed inside a 100 liters vacuum chamber with two optical windows: the first (in ZnSe) for the laser beam and the second (in fused quartz) for the pendulum visualization. A TEA-CO{sub 2} laser beam is focused to the samples providing ablation and transferring linear moment to the pendulum as a whole. A CCD video camera captures the oscillatory movement of the pendulum and the its trajectory is obtained by image processing. By fitting the trajectory of the pendulum to a dumped sinusoidal curve is possible to obtain the amplitude of the movement which is directly related to the momentum transfered to the sample.

  6. Ablation by ultrashort laser pulses: Atomistic and thermodynamic analysis of the processes at the ablation threshold

    Microsoft Academic Search

    Arun K. Upadhyay; Nail A. Inogamov; Bärbel Rethfeld; Herbert M. Urbassek

    2008-01-01

    Ultrafast laser irradiation of solids may ablate material off the surface. We study this process for thin films using molecular-dynamics simulation and thermodynamic analysis. Both metals and Lennard-Jones (LJ) materials are studied. We find that despite the large difference in thermodynamical properties between these two classes of materials---e.g., for aluminum versus LJ the ratio Tc\\/Ttr of critical to triple-point temperature

  7. Ablation by ultrashort laser pulses: Atomistic and thermodynamic analysis of the processes at the ablation threshold

    Microsoft Academic Search

    Arun K. Upadhyay; Nail A. Inogamov; Baerbel Rethfeld; Herbert M. Urbassek

    2008-01-01

    Ultrafast laser irradiation of solids may ablate material off the surface. We study this process for thin films using molecular-dynamics simulation and thermodynamic analysis. Both metals and Lennard-Jones (LJ) materials are studied. We find that despite the large difference in thermodynamical properties between these two classes of materials--e.g., for aluminum versus LJ the ratio T{sub c}\\/T{sub tr} of critical to

  8. Endometrial laser ablation in rabbits: A comparative study of three laser types

    Microsoft Academic Search

    Carlos Rosenberg; Yona Tadir; Diana Braslavsky; Benjamin Fisch; Ziv Karni; Jardena Ovadia

    1990-01-01

    Endometrial laser ablation is one of the alternatives to hysterectomy in cases of intractable uterine bleeding. It is currently performed using the Nd:YAG laser at 1.06 microns. The aim of this study was to compare the tissue effect of three types of laser irradiation (Nd:YAG laser at 1.06 and 1.32 microns and holmium laser at 2.12 microns) on the rabbit

  9. Next generation Er:YAG fractional ablative laser

    NASA Astrophysics Data System (ADS)

    Heinrich, A.; Vizhanyo, A.; Krammer, P.; Summer, S.; Gross, S.; Bragagna, T.; Böhler, C.

    2011-03-01

    Pantec Biosolutions AG presents a portable fractional ablative laser system based on a miniaturized diode pumped Er:YAG laser. The system can operate at repetition rates up to 500 Hz and has an incorporated beam deflection unit. It is smaller, lighter and cost efficient compared to systems based on lamp pumped Er:YAG lasers and incorporates a skin layer detection to guarantee precise control of the microporation process. The pulse parameters enable a variety of applications in dermatology and in general medicine, as demonstrated by first results on transdermal drug delivery of FSH (follicle stimulating hormone).

  10. Temperature profiles of 980- and 1,470-nm endovenous laser ablation, endovenous radiofrequency ablation and endovenous steam ablation.

    PubMed

    Malskat, W S J; Stokbroekx, M A L; van der Geld, C W M; Nijsten, T E C; van den Bos, R R

    2014-03-01

    Endovenous thermal ablation (EVTA) techniques are very effective for the treatment of varicose veins, but their exact working mechanism is still not well documented. The lack of knowledge of mechanistic properties has led to a variety of EVTA protocols and a commercially driven dissemination of new or modified techniques without robust scientific evidence. The aim of this study is to compare temperature profiles of 980-and 1,470-nm endovenous laser ablation (EVLA), segmental radiofrequency ablation (RFA), and endovenous steam ablation (EVSA). In an experimental setting, temperature measurements were performed using thermocouples; raw potato was used to mimic a vein wall. Two laser wavelengths (980 and 1,470 nm) were used with tulip-tip fibers and 1,470 nm also with a radial-emitting fiber. Different powers and pullback speeds were used to achieve fluences of 30, 60, and 90 J/cm. For segmental RFA, 1 cycle of 20 s was analyzed. EVSA was performed with two and three pulses of steam per centimeter. Maximum temperature increase, time span of relevant temperature increase, and area under the curve of the time of relevant temperature increase were measured. In all EVLA settings, temperatures increased and decreased rapidly. High fluence is associated with significantly higher temperatures and increased time span of temperature rise. Temperature profiles of 980- and 1,470-nm EVLA with tulip-tip fibers did not differ significantly. Radial EVLA showed significantly higher maximum temperatures than tulip-tip EVLA. EVSA resulted in mild peak temperatures for longer durations than EVLA. Maximum temperatures with three pulses per centimeter were significantly higher than with two pulses. RFA temperature rises were relatively mild, resulting in a plateau-shaped temperature profile, similar to EVSA. Temperature increase during EVLA is fast with a high-peak temperature for a short time, where EVSA and RFA have longer plateau phases and lower maximum temperatures. PMID:24292197

  11. Laser-induced-plasma-assisted ablation for glass microfabrication

    NASA Astrophysics Data System (ADS)

    Hong, Minghui; Sugioka, Koji; Wu, Ding J.; Wong, L. L.; Lu, Yongfeng; Midorikawa, Katsumi; Chong, Tow Chong

    2001-10-01

    Glass is a hard transparent material with many applications in Photonics and advanced display industries. It is a high challenge to achieve crack-free glass microfabrication due to its special material characteristics. Laser-induced-plasma- assisted ablation is applied in this study to get the high quality glass microfabrication. In this processing, the laser beam goes through the glass substrate first and then irradiates on a solid target behind. For laser fluence above ablation threshold for the target, the generated plasma flies forward at a high speed. At a small target-to-substrate distance, there are strong interactions among laser light, target plasma and glass materials at the rear side of the substrate. Light absorption characteristic at the glass substrate is modified since the plasma may soften and dope into the glass in the interaction area. To have a better understanding of this processing, signal diagnostics are carried out to study the dynamic interaction. It is found that glass microfabrication is closely related to laser fluence, target-to-substrate distance, laser spot size and laser beam scanning speed. With proper control of the processing parameters, glass surface marking patterning and cutting can be achieved. With different materials as the targets, color marking of glass substrate can be obtained.

  12. Excimer laser ablation of plasma polymers for cell and tissue culture applications

    NASA Astrophysics Data System (ADS)

    Thissen, Helmut; Hayes, Jason P.; Hartley, Patrick G.; Johnson, Graham; Harvey, Erol C.; Griesser, Hans J.

    2001-04-01

    The two-dimensional control of cell adhesion is desired for a number of cell- and tissue culture applications. Thus, a suitable method for the two-dimensional control over surface chemistry, which leads to the display of cell-adhesive and non-adhesive signals is required. In our study, allylamine plasma polymer (ALAPP) deposition has been used to provide a cell-adhesive substrate, while additional grafting of poly(ethylene oxide) (PEO) on ALAPP surfaces has been used to prevent cell adhesion. Two-dimensional control over the surface chemistry was achieved using excimer laser ablation. Ablation experiments were carried out using a 248 nm excimer laser with energy densities of 17 - 1181 mJ/cm2 and 1 - 16 pulses per area. Results obtained by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) show controlled thickness ablation of the plasma polymer and the additional PEO graft polymer. Cell culture experiments using bovine corneal epithelial cells show that two-dimensional control of cell adhesion can be achieved by using appropriate masks in the laser beam.

  13. Ablative skin resurfacing with a novel microablative CO2 laser.

    PubMed

    Gotkin, Robert H; Sarnoff, Deborah S; Cannarozzo, Giovanni; Sadick, Neil S; Alexiades-Armenakas, Macrene

    2009-02-01

    Carbon dioxide (CO2) laser skin resurfacing has been a mainstay of facial rejuvenation since its introduction in the mid 1990s. Recently, a new generation of fractional or microablative CO2 lasers has been introduced to the marketplace. According to the concept of fractional photothermolysis, these lasers ablate only a fraction of the epidermal and dermal architecture in the treatment area. An array of microscopic thermal wounds is created that ablates the epidermis and dermis within very tiny zones; adjacent to these areas, the epidermis and dermis are spared. This microablative process of laser skin resurfacing has proven safe and effective not only for facial rejuvenation, but elsewhere on the body as well. It is capable of improving wrinkles, acne scars, and other types of atrophic scars and benign pigmented lesions associated with elastotic, sun-damaged skin. Because of the areas of spared epidermis and dermis inherent in a procedure that employs fractional photothermolysis, healing is more rapid compared to fully ablative CO2 laser skin resurfacing and downtime is proportionately reduced. A series of 32 consecutive patients underwent a single laser resurfacing procedure with the a new microablative CO2 laser. All patients were followed for a minimum of 6 months and were asked to complete patient satisfaction questionnaires; a 6 month postoperative photographic evaluation by an independent physician, not involved in the treatment, was also performed. Both sets of data were graded and reported on a quartile scale. Results demonstrated greater than 50% improvement in almost all patients with those undergoing treatment for wrinkles, epidermal pigment or solar elastosis deriving the greatest change for the better (>75%). PMID:19213229

  14. Reassembling Solid Materials by Femtosecond Laser Ablation: Case of Aluminum Nitride

    NASA Astrophysics Data System (ADS)

    Kobayashi, Tohru; Matsuo, Yukari

    2013-06-01

    Through atomization and ionization, we could completely alter the composition of a nonconductive material, aluminum nitride, by femtosecond laser ablation. Preferential production of pure aluminum cluster cations Aln+ (n?32) reflects not only their higher energetic stability compared with mixed clusters AlnNm+ but also completion of thermal relaxation in ablation plasma. Observation of metastable dissociation of Aln+ indicates that cluster cations have still enough internal energy for dissociation to occur, although the process is much slower than the cluster formation. Almost no cluster formation has been observed after nanosecond laser ablation of aluminum nitride, which highlights the distinct nature of ablation plasma produced by femtosecond laser ablation.

  15. Comparison of soft and hard tissue ablation with sub-ps and ns pulse lasers

    SciTech Connect

    Da Silva, L.B.; Stuart, B.C.; Celliers, P.M.; Feit, M.D.; Glinsky, M.E.; Heredia, N.J.; Herman, S.; Lane, S.M.; London, R.A.; Matthews, D.L.; Perry, M.D.; Rubenchik, A.M. [Lawrence Livermore National Lab., CA (United States); Chang, T.D. [Veterans Administration Hospital, Martinez, CA (United States); Neev, J. [Beckman Laser Inst. and Medical Clinic, Irvine, CA (United States)

    1996-05-01

    Tissue ablation with ultrashort laser pulses offers several unique advantages. The nonlinear energy deposition is insensitive to tissue type, allowing this tool to be used for soft and hard tissue ablation. The localized energy deposition lead to precise ablation depth and minimal collateral damage. This paper reports on efforts to study and demonstrate tissue ablation using an ultrashort pulse laser. Ablation efficiency and extent of collateral damage for 0.3 ps and 1000 ps duration laser pulses are compared. Temperature measurements of the rear surface of a tooth section is also presented.

  16. Hydrodynamic simulation of ultrashort pulse laser ablation of gold film

    NASA Astrophysics Data System (ADS)

    Yu, Dong; Jiang, Lan; Wang, Feng; Shi, Xuesong; Qu, Liangti; Lu, Yongfeng

    2015-06-01

    The electron collision frequency in a hydrodynamic model was improved to match the laser energy absorbed with experimental data. The model calculation was used to investigate the ablation depth and the dependence of the threshold fluence of gold film on pulse width and wavelength. Two methods for estimating the ablation depth are introduced here with their respective scope of application. The dependence of the threshold fluence of gold film on the pulse width of the laser with a 1053 nm center wavelength agreed well with the experimental data. It was also observed that for pulses shorter than ~200 ps, the threshold fluence showed linear dependence on the logarithm of pulse width and increased with the wavelength, which was different from previous results.

  17. Targets on superhydrophobic surfaces for laser ablation ion sources

    NASA Astrophysics Data System (ADS)

    Renisch, D.; Beyer, T.; Blaum, K.; Block, M.; Düllmann, Ch. E.; Eberhardt, K.; Eibach, M.; Nagy, Sz.; Neidherr, D.; Nörtershäuser, W.; Smorra, C.

    2012-06-01

    Target preparation techniques for a laser ablation ion source at the Penning-trap mass spectrometer TRIGA-TRAP have been investigated with regard to future experiments with actinides. To be able to perform mass measurements on these nuclides considering their limited availability, an efficient target preparation technique is mandatory. Here, we report on a new approach for target production using backings, which are pretreated in a way that a superhydrophobic surface is formed. This resulted in improved targets with a more homogeneous distribution of the target material compared to standard techniques with unmodified backings. It was demonstrated that the use of these new targets in a laser ablation ion source improved the ion production significantly.

  18. Investigation of laser ablation of CVD diamond film

    NASA Astrophysics Data System (ADS)

    Chao, Choung-Lii; Chou, W. C.; Ma, Kung-Jen; Chen, Ta-Tung; Liu, Y. M.; Kuo, Y. S.; Chen, Ying-Tung

    2005-04-01

    Diamond, having many advanced physical and mechanical properties, is one of the most important materials used in the mechanical, telecommunication and optoelectronic industry. However, high hardness value and extreme brittleness have made diamond extremely difficult to be machined by conventional mechanical grinding and polishing. In the present study, the microwave CVD method was employed to produce epitaxial diamond films on silicon single crystal. Laser ablation experiments were then conducted on the obtained diamond films. The underlying material removal mechanisms, microstructure of the machined surface and related machining conditions were also investigated. It was found that during the laser ablation, peaks of the diamond grains were removed mainly by the photo-thermal effects introduced by excimer laser. The diamond structures of the protruded diamond grains were transformed by the laser photonic energy into graphite, amorphous diamond and amorphous carbon which were removed by the subsequent laser shots. As the protruding peaks gradually removed from the surface the removal rate decreased. Surface roughness (Ra) was improved from above 1?m to around 0.1?m in few minutes time in this study. However, a scanning technique would be required if a large area was to be polished by laser and, as a consequence, it could be very time consuming.

  19. Pre-ignition laser ablation of nanocomposite energetic materials

    SciTech Connect

    Stacy, S. C.; Massad, R. A.; Pantoya, M. L. [Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)] [Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)

    2013-06-07

    Laser ignition of energetic material composites was studied for initiation with heating rates from 9.5 Multiplication-Sign 10{sup 4} to 1.7 Multiplication-Sign 10{sup 7} K/s. This is a unique heating rate regime for laser ignition studies because most studies employ either continuous wave CO{sub 2} lasers to provide thermal ignition or pulsed Nd:YAG lasers to provide shock ignition. In this study, aluminum (Al) and molybdenum trioxide (MoO{sub 3}) nanoparticle powders were pressed into consolidated pellets and ignited using a Nd:YAG laser (1064 nm wavelength) with varied pulse energy. Results show reduced ignition delay times corresponding to laser powers at the ablation threshold for the sample. Heating rate and absorption coefficient were determined from an axisymmetric heat transfer model. The model estimates absorption coefficients from 0.1 to 0.15 for consolidated pellets of Al + MoO{sub 3} at 1064 nm wavelength. Ablation resulted from fracturing caused by a rapid increase in thermal stress and slowed ignition of the pellet.

  20. Modeling of laser ablation and fragmentation of human calculi

    SciTech Connect

    Gitomer, S.; Jones, R.D.; Howsare, C.

    1989-01-01

    The large-scale radiation-hydrodynamics computer code LASNEX, has been used to model experimental results in the laser ablation and fragmentation of renal and biliary calculi. Recent experiments have demonstrated laser ablation and fragmentation of human calculi in vitro and in vivo. In the interaction, laser light incident upon the calculus is of sufficient intensity to produce a plasma (a hot ionized gas). The physical picture which emerges is as follows. The plasma couples to acoustic and shear waves which then propagate through the dense stone material, causing spall and fracture by reflection from material discontinuities or boundaries. Experiments have thus far yielded data on the interaction against which models can be tested. Data on the following have been published: (1) light emission, (2) absorption and emission spectra, (3) fragmentation efficiency, (4) cavitation bubble dynamics and (5) mass removal. We have performed one dimensional simulations of the laser-matter interaction to elucidate the important physical mechanisms. We find that good quantitative fits between simulation and experiment are obtained for visible light emission, electron temperature, electron density, plasma pressure and cavitation bubble growth. With regard to mass removal, experiment and simulation are consistent with each other and give an excellent estimate of the ablation threshold. The modeling indicates that a very small ablation layer at the surface of the calculus is responsible for significant mass loss by fragmentation within the bulk of the calculus. With such quantitative fits in hand, we believe this type of modeling can now be applied to the study of other procedures involving plasma formation of interest to the medical community. 25 refs., 7 figs.

  1. Growth of epitaxial thin films by pulsed laser ablation

    SciTech Connect

    Lowndes, D.H.

    1992-10-01

    High-quality, high-temperature superconductor (HTSc) films can be grown by the pulsed laser ablation (PLA) process. This article provides a detailed introduction to the advantages and curent limitations of PLA for epitaxial film growth. Emphasis is placed on experimental methods and on exploitation of PLA to control epitaxial growth at either the unit cell or the atomic-layer level. Examples are taken from recent HTSc film growth. 33 figs, 127 refs. (DLC)

  2. Growth of epitaxial thin films by pulsed laser ablation

    SciTech Connect

    Lowndes, D.H.

    1992-01-01

    High-quality, high-temperature superconductor (HTSc) films can be grown by the pulsed laser ablation (PLA) process. This article provides a detailed introduction to the advantages and curent limitations of PLA for epitaxial film growth. Emphasis is placed on experimental methods and on exploitation of PLA to control epitaxial growth at either the unit cell or the atomic-layer level. Examples are taken from recent HTSc film growth. 33 figs, 127 refs. (DLC)

  3. Nanosecond Infrared Laser for Tissue Ablation

    Microsoft Academic Search

    G. S. Edwards; R. D. Pearlstein; M. L. Copeland; M. S. Hutson; K. Latone; A. Spiro; G. Pasmanik

    2007-01-01

    The Mark-III Free-Electron Laser (FEL), operating at the 6.45mum wavelength, has been used successfully in human surgery. Due to the FEL's size and cost, there has been interest in the development of a compact, inexpensive infrared laser for human surgical applications. We have investigated the role of the FEL superpulse, leading to the prediction that nanosecond pulses can satisfy the

  4. Laser ablation lithography on thermoelectric semiconductor

    NASA Astrophysics Data System (ADS)

    Semchuk, O. Yu.; Semioshko, V. N.; Grechko, L. G.; Willander, M.; Karlsteen, M.

    2006-04-01

    In this paper, experimental results of the investigation of the periodic structure on thermoelectric semiconductor Cu 2Se are presented. Periodic structures were formed on surfaces of semiconductors due to multi-beam interaction of Q-switched Nd:YAG laser, which was operated in the lowest order of Gaussian mode and pulse duration 7 ns. Surface temperature evolution and transient reflectivity are studied during laser treatment. Creation of Cu islands in the maximal intensity of interference pattern was found.

  5. Characteristics of optical emission intensities and bubblelike phenomena induced by laser ablation in supercritical fluids

    NASA Astrophysics Data System (ADS)

    Takada, Noriharu; Machmudah, Siti; Goto, Hiroshi; Wahyudiono; Goto, Motonobu; Sasaki, Koichi

    2014-01-01

    We investigated the characteristics of laser ablation phenomena in supercritical fluids by optical emission and shadowgraph imaging. In comparison with laser ablation in liquid H2O, the optical emission of a laser ablation plasma produced in supercritical H2O had a longer lifetime and a larger transport length. It was found in supercritical CO2 that laser ablation plasmas with bright optical emissions were produced at a mass density of approximately 300 kg/m3. A clear correlation between the optical emission intensity and the density fluctuation was not observed in our experimental results, which were obtained in a regime deviated from the critical point. Bubblelike hollows were observed by shadowgraph imaging in both supercritical H2O and CO2. The dynamics of the bubblelike hollows were different from the dynamics of a cavitation bubble induced by laser ablation in a liquid medium but relatively similar to the dynamics of ambient gas in gas-phase laser ablation.

  6. Update On CO{sub 2} Laser Ablation Of Polyoxymethylene At 101 kPa

    SciTech Connect

    Sinko, John E. [Micro-Nano Global Center of Excellence, Nagoya University, Nagoya, 464-8603 (Japan); Scharring, Stefan; Eckel, Hans-Albert [Studies and Concepts Group, German Aerospace Center (DLR), D-70569 Stuttgart, Pfaffenwaldring 38-40 (Germany); Ogita, Naoya; Sasoh, Akihiro [Department of Aerospace Engineering, Nagoya University, Nagoya, 464-8603 (Japan); Roeser, Hans-Peter [Institute of Space Systems, University of Stuttgart, D-70569 Stuttgart, Pfaffenwaldring 31 (Germany)

    2010-10-08

    Recent work has brought about a renewed interest in CO{sub 2} laser ablation studies of polyoxymethylene, due to its potential as a test target for enhancing modern understanding of the laser ablation process. In this paper, new results taken in air at atmosphere pressure are reported, including data measured at institutions in Germany and Japan, which increase the body of literature data on CO{sub 2} laser ablation of polyoxymethylene. The results are discussed in terms of aerospace parameters such as the momentum coupling coefficient and specific impulse, and are compared to a previous literature study. The threshold fluence is specified for ablation of polyoxymethylene by CO{sub 2} laser radiation. Fluences higher (and lower) than previously tested for CO{sub 2} laser ablation were studied herein, and record specific impulse values for CO{sub 2} laser ablation of flat polyoxymethylene are also reported here.

  7. Experimental and computational study of complex shockwave dynamics in laser ablation plumes in argon atmosphere

    SciTech Connect

    Harilal, S. S.; Miloshevsky, G. V.; Diwakar, P. K.; LaHaye, N. L.; Hassanein, A. [Center for Materials under Extreme Environment, and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2012-08-15

    We investigated spatio-temporal evolution of ns laser ablation plumes at atmospheric pressure, a favored condition for laser-induced breakdown spectroscopy and laser-ablation inductively coupled plasma mass-spectrometry. The 1064 nm, 6 ns pulses from a Nd:YAG laser were focused on to an Al target and the generated plasma was allowed to expand in 1 atm Ar. The hydrodynamic expansion features were studied using focused shadowgraphy and gated 2 ns self-emission visible imaging. Shadowgram images showed material ejection and generation of shock fronts. A secondary shock is observed behind the primary shock during the time window of 100-500 ns with instabilities near the laser cone angle. By comparing the self-emission images obtained using fast photography, it is concluded that the secondary shocks observed in the shadowgraphy were generated by fast moving target material. The plume front estimates using fast photography exhibited reasonable agreement with data obtained from shadowgraphy at early times {<=}400 ns. However, at later times, fast photography images showed plume confinement while the shadowgraphic images showed propagation of the plume front even at greater times. The structure and dynamics of the plume obtained from optical diagnostic tools were compared to numerical simulations. We have shown that the main features of plume expansion in ambient Ar observed in the experiments can be reproduced using a continuum hydrodynamics model which provided valuable insight into the expansion dynamics and shock structure of the plasma plume.

  8. Spectroscopic evidence of positive clusters in Ag colloids obtained by laser ablation in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Giorgetti, E.; Marsili, P.; Muniz-Miranda, M.; Gellini, C.; Giammanco, F.

    2014-10-01

    We have found evidence of positive cluster formation during the laser ablation process of a silver target in aqueous solutions. In particular, by employing in situ shot-by-shot UV-vis spectroscopy in the early stages of the ablation, we observed a weak and unstable absorption band around 266 nm and a more stable one around 290 nm, which could be assigned to charged clusters like Ag{3/2+} and Ag{4/2+}, respectively. Surface-enhanced Raman scattering experiments performed with a test molecule adsorbed on a silver colloid obtained in pure water were compatible with the presence of Ag{4/2+} active sites on the surface of the Ag nanoparticles.

  9. Optical probe investigation of laser ablated carbon plasma plume in nitrogen ambient

    SciTech Connect

    Singh, Ravi Pratap; Gupta, Shyam L.; Thareja, Raj K. [Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016 Uttar Pradesh (India)] [Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016 Uttar Pradesh (India)

    2013-12-15

    We report the study of carbon plasma produced using 1064 nm laser in nitrogen ambient at atmospheric pressure using 2-dimensional fast imaging of ablated plume, optical emission spectroscopy, and optical probe at 532 nm for interferometry and shadowgraphy. The dominance of C{sub 2} and CN molecules over ionic species at later stages of expanding carbon plasma plume is reported. The observed ring structure in shadowgrams and change in the direction of fringe shift from positive to negative in recorded interferograms are correlated with the relative abundance of different species in the plasma plume as function of time delay with respect to ablating pulse. An agreement in observed onset time of formation of clusters/atomic species or low ionic species using different diagnostic techniques has been reported.

  10. Laser induced effects on ZnO targets upon ablation at 266 and 308 nm wavelengths

    SciTech Connect

    Jadraque, Maria; Martin, Margarita [Instituto de Quimica Fisica 'Rocasolano', C.S.I.C. Serrano 119, 28006 Madrid (Spain); Domingo, Concepcion [Instituto de Estructura de la Materia, C.S.I.C. Serrano 121, 28006 Madrid (Spain)

    2008-07-15

    The development of structural changes in ZnO targets, upon laser irradiation at the wavelengths of 266 and 308 nm, is studied by Raman spectroscopy. At the wavelength of 308 nm, oxygen vacancies are found to develop monotonically with increasing laser intensity. At 266 nm, a structural change in the irradiated ZnO targets, possibly related to nanostructuring, is observed above the laser fluence of 0.45 J cm{sup -2}. The different natures of the laser target interaction processes taking place at both wavelengths are investigated through the characterization of the composition and energy distribution of the species ejected in the ablation. The energy of the neutral Zn and Zn{sub 2} present in the ablation at 308 nm shows a smooth dependence on laser fluence which is consistent with the observed smooth development of oxygen vacancies. At 266 nm, the average kinetic energy of the ejected fragments is higher than at 308 nm and changes abruptly with the ablating laser fluence, consistently with the presence of a fluence threshold above which structural transform is observed at this wavelength. The plume shows the same neutral composition (Zn, ZnO, and Zn{sub 2}) at both wavelengths but the dependence on fluence of the ratio of neutral atomic Zn to the dimer Zn{sub 2} shows significant differences. From the latter, different temperature regimes can be inferred in the plume generated at both wavelengths. At 266 nm the cationic composition of the plume is mainly stoichiometric whereas at 308 nm ZnO{sub 2(3)}H{sub 2(1)}{sup +} cations have the highest intensity.

  11. Phase explosion in atmospheric pressure infrared laser ablation from water-rich targets

    E-print Network

    Vertes, Akos

    Phase explosion in atmospheric pressure infrared laser ablation from water-rich targets Zhaoyang for preparative, medical,13 and analytical applications11 e.g., atmospheric pressure matrix-assisted laser at atmospheric pressure in the presence of phase ex- plosion. Compared to laser ablation in vacuum, in a back

  12. Pulsed laser ablation of borax target in vacuum and hydrogen DC glow discharges

    NASA Astrophysics Data System (ADS)

    Kale, A. N.; Miotello, A.; Mosaner, P.

    2006-09-01

    The aim of our experiment was to produce a material with B sbnd H bonds for applications in hydrogen storage and generation. By using KrF excimer laser ( ? = 248 nm) ablation of borax (Na 2B 4O 7) target, thin films were deposited on KBr and silicon substrates. Ablation was performed both in vacuum and in hydrogen atmosphere. DC glow discharge technique was utilized to enhance hydrogen gas ionization. Experiments were performed using laser fluence from 5 to 20 J/cm 2. Films were deposited under gas pressure of 1 × 10 -5 to 5 × 10 -2 mbar and substrate temperatures of 130-450 °C. Scanning electron microscopy analysis of films showed presence of circular particulates. Film thickness, roughness and particulates number increased with increase in laser fluence. Energy dispersive X-ray spectroscopy analysis shows that sodium content in the particulates is higher than in the target. This effect is discussed in terms of atomic arrangements (both at surface and bulk) in systems where ionic and covalent bonds are present and by looking at the increased surface/bulk ratio of the particulates with respect to the deposited films. The Fourier transform infrared spectroscopy measurements showed presence of B sbnd O stretching and B sbnd O sbnd B bending bonds. Possible reasons for absence of B sbnd H bonds are attributed to binding enthalpy of the competing molecules.

  13. Laser microprobe and resonant laser ablation for depth profile measurements of hydrogen isotope atoms contained in graphite

    Microsoft Academic Search

    Masafumi Yorozu; Tatsuya Yanagida; Terunobu Nakajyo; Yasuhiro Okada; Akira Endo

    2001-01-01

    We measured the depth profile of hydrogen atoms in graphite by laser microprobing combined with resonant laser ablation. Deuterium-implanted graphite was employed for the measurements. The sample was ablated by a tunable laser with a wavelength corresponding to the resonant wavelength of1S-2S of deuterium with two-photon excitation. The ablated deuterium was ionized by a 2 + 1 resonant ionization process.

  14. Therapeutic ratio quantifies laser antisepsis: Ablation ofPorphyromonas gingivalis with dental lasers

    Microsoft Academic Search

    David M. Harris; Michael Yessik

    2004-01-01

    Background and Objectives: It is established that both pulsed Nd:YAG (1,064 nm) and continuous diode (810 nm) dental lasers kill pathogenic bacteria (laser antisepsis), but a quantitative method for determining clinical dosimetry does not exist. The purpose of this study was to develop a method to quantify the efficacy of ablation of Porphyromo- nas gingivalis (Pg) in vitro for two

  15. Excimer laser patterned dielectric masks for the fabrication of diffractive optical elements by laser ablation

    Microsoft Academic Search

    D. Schäfer; J. Ihlemann; K. Mann; G. Marowsky

    1999-01-01

    Masks for laser processing are generated by laser ablation patterning of dielectric layer systems. The application of these masks for the rapid fabrication of diffractive optical elements (DOEs) is presented. The diffractive optical elements are designed as phase-only elements, assuming an illumination with a plane wave. A continuous phase function is calculated using an iterative Fourier transform algorithm (IFTA). This

  16. Corneal ablation using the pulse stretched free electron laser

    NASA Astrophysics Data System (ADS)

    Mackanos, Mark A.; Joos, Karen M.; Kozub, John A.; Jansen, E. D.

    2005-04-01

    The Mark-III Free Electron Laser (FEL), tuned to ?=6.45 ?m has been demonstrated to provide for efficient ablation in ocular and neural tissues with minimal collateral damage. To date, the role of the FEL pulse structure on the mechanism of ablation has not been determined. In an effort to study the role of the FEL micropulse on the ablation of corneal tissue, the native pulse structure of the FEL, a 2.85 gigahertz repetition of picosecond pulses within a five microsecond macropulse envelope, was changed using a a pulse stretcher. This device changes the duration of the micropulse from 1 picosecond to 30-200 picoseconds in length, thus reducing the peak intensity of the micropulse by as much as 200x the original intensity, while the macropulse energy remains unchanged. Two basic metrics were studied: the ablation threshold on water and the ablation crater depth on gelatin. These metrics were employed at ?=6.45 and 6.1 ?m for 1, 100, and 200 picoseconds in micropulse duration. The results showed a very slight difference between the 1, 100, and 200 picosecond micropulse duration, given a 200 fold decrease in peak energy for both the threshold and crater depth measurements. Brightfield imaging was also performed to probe the ablation dynamics and showed no difference between the 1 and 200 ps micropulses. The effect of changing the micropulse duration was studied on the ablation of canine cornea. Craters (500 micron diameter) were created with 25 pulses at three times the ablation threshold as determined for water on freshly enucleated corneas within 12 hours of removal. Three rows of seven craters were created on the center of each cornea. The native one picosecond micropulse and 200 picosecond stretched micropulse were compared at ?=6.1 and 6.45 ?m. Histological data shows that less thermal damage is present at 6.1 ?m compared with 6.45 ?m however, there is no significant difference between the native and stretched pulses with respect to thermal damage.

  17. Femtosecond laser bone ablation with a high repetition rate fiber laser source.

    PubMed

    Mortensen, Luke J; Alt, Clemens; Turcotte, Raphaël; Masek, Marissa; Liu, Tzu-Ming; Côté, Daniel C; Xu, Chris; Intini, Giuseppe; Lin, Charles P

    2015-01-01

    Femtosecond laser pulses can be used to perform very precise cutting of material, including biological samples from subcellular organelles to large areas of bone, through plasma-mediated ablation. The use of a kilohertz regenerative amplifier is usually needed to obtain the pulse energy required for ablation. This work investigates a 5 megahertz compact fiber laser for near-video rate imaging and ablation in bone. After optimization of ablation efficiency and reduction in autofluorescence, the system is demonstrated for the in vivo study of bone regeneration. Image-guided creation of a bone defect and longitudinal evaluation of cellular injury response in the defect provides insight into the bone regeneration process. PMID:25657872

  18. Periodic patterning of silicon by direct nanosecond laser interference ablation

    NASA Astrophysics Data System (ADS)

    Tavera, T.; Pérez, N.; Rodríguez, A.; Yurrita, P.; Olaizola, S. M.; Castaño, E.

    2011-11-01

    The production of periodic structures in silicon wafers by four-beam is presented. Because laser interference ablation is a single-step and cost-effective process, there is a great technological interest in the fabrication of these structures for their use as antireflection surfaces. Three different laser fluences are used to modify the silicon surface (0.8 J cm-2, 1.3 J cm-2, 2.0 J cm-2) creating bumps in the rim of the irradiated area. Laser induced periodic surface structures (LIPSS), in particular micro and nano-ripples, are also observed. Measurements of the reflectivity show a decrease in the reflectance for the samples processed with a laser fluence of 2.0 J cm-2, probably caused by the appearance of the nano-ripples in the structured area, while bumps start to deteriorate.

  19. Laser intracavity absorption spectroscopy

    Microsoft Academic Search

    V. M. Baev; T. Latz; P. E. Toschek

    1999-01-01

    .   Emission spectra of multimode lasers are very sensitive to spectrally selective extinction in their cavity. This phenomenon\\u000a allows the quantitative measurement of absorption. The sensitivity of measurements of intracavity absorption grows with the\\u000a laser pulse duration. The ultimate sensitivity obtained with a cw laser is set by various perturbations of the light coherence,\\u000a such as quantum noise, Rayleigh scattering,

  20. Production of nanoparticles by laser-induced ablation of metals in liquids

    SciTech Connect

    Bozon-Verduraz, F; Brayner, R [ITODYS, Universite Paris (France); Voronov, Valerii V [Laser Materials and Technology Research Center, A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Kirichenko, N A; Simakin, Aleksandr V; Shafeev, Georgii A [Wave Research Centre, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2003-08-31

    The production of noble metal (Ag and Au) nanoparticles upon the ablation of metal targets in liquids (H{sub 2}O, C{sub 2}H{sub 5}OH, etc.) caused by irradiation by a copper vapour laser is studied. The nanoparticles emerging in a liquid are investigated using X-ray diffractometry, optical absorption spectroscopy, and high-resolution transmission electron microscopy. The colloidal nanoparticle solutions exhibits a distinct plasmon resonance at 520 and 400 nm for Au and Ag, respectively. It is shown that the proximity of laser wavelength to the resonance makes it possible to decrease the dimension of nanoparticles by irradiating the colloidal solution. The size distribution function of nanoparticles is simulated taking into account the production, coagulation, and splitting of nanopartiles in the laser beam. (special issue devoted to the memory of academician a m prokhorov)

  1. Effect of laser parameters on laser ablation and laser-induced plasma formation: A numerical modeling investigation

    Microsoft Academic Search

    Annemie Bogaerts; Zhaoyang Chen

    2005-01-01

    A comprehensive numerical model has recently been developed for nanosecond (ns) laser ablation of metallic targets, describing the processes of target heating, melting and vaporization, the resulting plume expansion in 1 atm helium gas, as well as plasma formation in the plume. In the present paper, we investigate the influence of laser parameters, i.e., laser irradiance, pulse duration and wavelength,

  2. Femtosecond laser plasma plume characteristics in the nanojoule ablation regime

    SciTech Connect

    Banerjee, S. P.; Chen, Zhijiang; Fedosejevs, R. [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G2V4 (Canada)] [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G2V4 (Canada)

    2013-05-14

    Laser ablation of chromium with nanojoule energy UV femtosecond pulses under background pressure conditions between 0.3 Torr and 700 Torr is studied and the corresponding plasma plume images at different times after irradiation are measured. The ablation focal spot is less than or the order of a micron when 170 nJ of laser pulse energy is used. This low pulse energy leads to short lifetimes of the plasma of the order of tens of nanoseconds. The plume shape changes with ambient pressure due to the collision with background gas. An axially stretched plume changes to a more circular plume as the pressure increases. In addition, a separation of the ionic and atomic components is observed at lower pressure. These two components move at significantly different velocities as well. The plasma plume expands at almost constant velocity at very low pressure but exhibits significant deceleration at higher pressure reaching an asymptotic stopping distance. Plume images are also obtained near the ablation threshold pulse energy. The plume characteristics are compared to different models of plume expansion.

  3. Laser ablation of a platinum target in water. III. Laser-induced reactions

    SciTech Connect

    Nichols, William T.; Sasaki, Takeshi; Koshizaki, Naoto [Nanoarchitectonics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan)

    2006-12-01

    This is the third paper in our series studying the laser-target-liquid interactions occurring in laser ablation in liquids (LAL). Here, laser ablation of a platinum target in pure water at 355 nm wavelength is studied as a function of laser energy. We describe three distinct reaction regimes between the ablated target species and water at different laser focusing conditions. At low laser fluence (<10 J/cm{sup 2}), material removal is caused by laser heating of the platinum surface and the primary products are small clusters with a large percentage of platinum atoms in a nonzero oxidation state. At intermediate fluences (10-70 J/cm{sup 2}), platinum nanoparticles are the primary products. Our previous studies demonstrated that in this fluence regime ablation occurs through both thermal vaporization and explosive ejection of molten droplets. In both cases reactivity is small due to the low reactivity of platinum with water. At high fluences (>70 J/cm{sup 2}), we find large, faceted particles that are attributed to the drying of PtO{sub x} gels formed by reactive plasma etching of the target. Taken together these results demonstrate that significant tunability in the target-liquid interaction is possible during nanomaterial synthesis by LAL.

  4. Laser ablation of polymer coatings allows for electromagnetic field enhancement mapping around nanostructures

    SciTech Connect

    Fiutowski, J.; Maibohm, C.; Kjelstrup-Hansen, J.; Rubahn, H.-G. [Mads Clausen Institute, NanoSYD, University of Southern Denmark, Alsion 2, DK-6400, Soenderborg (Denmark)

    2011-05-09

    Subdiffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures. The accompanying field enhancement substantially lowers the ablation threshold of the polymer film and thus creates local ablation spots and corresponding topographic modifications of the polymer film. Such modifications are quantified straightforwardly via scanning electron microscopy and atomic force microscopy. Thickness variation in the polymer film enables the investigation of either the initial ablation phase or ablation induced by collective enhancement effects.

  5. Femtosecond laser ablation characteristics of nickel-based superalloy C263

    Microsoft Academic Search

    N. G. Semaltianos; W. Perrie; M. Sharp; G. Dearden; S. Logothetidis; K. G. Watkins

    2009-01-01

    Femtosecond laser (180 fs, 775 nm, 1 kHz) ablation characteristics of the nickel-based superalloy C263 are investigated. The\\u000a single pulse ablation threshold is measured to be 0.26±0.03 J\\/cm2 and the incubation parameter ?=0.72±0.03 by also measuring the dependence of ablation threshold on the number of laser pulses.\\u000a The ablation rate exhibits two logarithmic dependencies on fluence corresponding to ablation determined

  6. A study of particle generation during laser ablation withapplications

    SciTech Connect

    Liu, Chunyi

    2005-08-12

    A study has been made of the generation of particles during laser ablation and has included size distribution measurements and observation of the formation processes. The particle size distribution with respect to different laser parameters was obtained in-line using a differential mobility analyzer (DMA) and a particle counter. The experimental results show that the particle size varies with laser energy, laser pulsewidth, ambient gas flow rate and sample properties. The results serve as a basis for controlling the size of nanoparticles generated by laser ablation. Laser shadowgraph imaging was used to study mass ejection processes and mechanisms. At higher laser irradiance, some particles were ejected in the liquid and even in the solid phase. Time-resolved images show the propagation of the shockwaves: external shockwaves propagate outward and decelerate, and internal shockwaves reflect back and forth between the gas contact surface and the sample surface. The internal shockwave is proposed to cause the ejection of liquid particles when the internal shockwave strikes the liquid molten layer. A simulation based on vapor plume expansion was carried out and provides satisfactory agreement with experimental results. Different material properties result in different particle ejection behavior:particle ejection for most materials including metals result in a conically shaped envelope for the ejected material while ejection for silicon resembles a liquid jet. The difference in density change when the materials melt was proposed to be an important factor in the different ejection behavior. The characteristics of particles generated by laser ablation have a strong influence on the chemical analysis of the irradiated sample. Large particles are more difficult to completely vaporize and ionize, and induced preferential vaporization causes fractionation (i.e. a detected chemical composition that differs from the sample material). Large particles also result in spikes in measurements using inductively coupled plasma mass spectrometry (ICP-MS) which result in errors. Three different methods were employed to study the effects of particle size on chemical analysis: generating smaller particles utilizing a fs laser, filtering out larger particles with a cascade impactor and altering the size distribution by using a second pulse to fracture particles generated from the first pulse. It was found that the chemical composition of the particles varies with particle size. The variation of the composition with respect to particle size was analyzed and it was proposed that it was related to the vapor formed particles condensing on larger ejected liquid droplets.

  7. Simulation of laser interaction with ablative plasma and hydrodynamic behavior of laser supported plasma

    SciTech Connect

    Tong Huifeng; Yuan Hong [Institute of Fluid Physics, Chinese Academy of Engineering Physics, P.O. Box 919-101, Mianyang, Sichuan 621900 (China); Tang Zhiping [CAS Key Laboratory for Mechanical Behavior and Design of Materials, Department of Mechanics and Mechanical Engineering, University of Science and Technology of China, Hefei 230026 (China)

    2013-01-28

    When an intense laser beam irradiates on a solid target, ambient air ionizes and becomes plasma, while part of the target rises in temperature, melts, vaporizes, ionizes, and yet becomes plasma. A general Godunov finite difference scheme WENO (Weighted Essentially Non-Oscillatory Scheme) with fifth-order accuracy is used to simulate 2-dimensional axis symmetrical laser-supported plasma flow field in the process of laser ablation. The model of the calculation of ionization degree of plasma and the interaction between laser beam and plasma are considered in the simulation. The numerical simulations obtain the profiles of temperature, density, and velocity at different times which show the evolvement of the ablative plasma. The simulated results show that the laser energy is strongly absorbed by plasma on target surface and that the velocity of laser supported detonation (LSD) wave is half of the ideal LSD value derived from Chapman-Jouguet detonation theory.

  8. Simulation of laser interaction with ablative plasma and hydrodynamic behavior of laser supported plasma

    NASA Astrophysics Data System (ADS)

    Tong, Huifeng; Yuan, Hong; Tang, Zhiping

    2013-01-01

    When an intense laser beam irradiates on a solid target, ambient air ionizes and becomes plasma, while part of the target rises in temperature, melts, vaporizes, ionizes, and yet becomes plasma. A general Godunov finite difference scheme WENO (Weighted Essentially Non-Oscillatory Scheme) with fifth-order accuracy is used to simulate 2-dimensional axis symmetrical laser-supported plasma flow field in the process of laser ablation. The model of the calculation of ionization degree of plasma and the interaction between laser beam and plasma are considered in the simulation. The numerical simulations obtain the profiles of temperature, density, and velocity at different times which show the evolvement of the ablative plasma. The simulated results show that the laser energy is strongly absorbed by plasma on target surface and that the velocity of laser supported detonation (LSD) wave is half of the ideal LSD value derived from Chapman-Jouguet detonation theory.

  9. Heat accumulation in microdrilled glass from ultraviolet laser ablation

    NASA Astrophysics Data System (ADS)

    Hidai, Hirofumi; Matsusaka, Souta; Chiba, Akira; Morita, Noboru

    2015-07-01

    We present numerical and experimental studies of heat accumulation during high-aspect-ratio ultraviolet laser microdrilling of glass. The dependence on pulse repetition rate of the ablation threshold was studied. The rate determines the amount of heat accumulation and temperature variation across the illuminated area. No change in the glass was observed for pulse energies below 1 µJ at 1 kHz; melting occurred at 0.3 µJ, with ablation at 0.7 µJ at 20 kHz. Also, the hole depth doubled when the pulse repetition rate was increased from 1 to 20 kHz. Moreover, the fluence of ~4 J/cm2 that passed through drilled holes at 1 kHz decreased to ~1 J/cm2 at 20 kHz.

  10. Heat accumulation in microdrilled glass from ultraviolet laser ablation

    NASA Astrophysics Data System (ADS)

    Hidai, Hirofumi; Matsusaka, Souta; Chiba, Akira; Morita, Noboru

    2015-04-01

    We present numerical and experimental studies of heat accumulation during high-aspect-ratio ultraviolet laser microdrilling of glass. The dependence on pulse repetition rate of the ablation threshold was studied. The rate determines the amount of heat accumulation and temperature variation across the illuminated area. No change in the glass was observed for pulse energies below 1 µJ at 1 kHz; melting occurred at 0.3 µJ, with ablation at 0.7 µJ at 20 kHz. Also, the hole depth doubled when the pulse repetition rate was increased from 1 to 20 kHz. Moreover, the fluence of ~4 J/cm2 that passed through drilled holes at 1 kHz decreased to ~1 J/cm2 at 20 kHz.

  11. Ultrasensitive Laser Spectroscopy.

    ERIC Educational Resources Information Center

    Kliger, David S.

    1985-01-01

    Examines techniques used to make ultrasensitive spectroscopic measurements. They include excitation, thermal lens, photo acoustic, and ionization spectroscopies. Guidelines and methods are provided for each technique; common uses and applications are explained. (DH)

  12. Hamdi et al, Laser Spectroscopy with nanometric gas cells: ... Laser spectroscopy with nanometric gas cells

    E-print Network

    Paris-Sud XI, Université de

    Hamdi et al, Laser Spectroscopy with nanometric gas cells: ... Laser spectroscopy with nanometric The high sensitivity of Laser Spectroscopy has made possible the exploration of atomic resonances in newly of interatomic collisions processes under the effect of confinement. 1 #12;Hamdi et al, Laser Spectroscopy

  13. Evaluation of the analytical capability of NIR femtosecond laser ablation-inductively coupled plasma mass spectrometry.

    PubMed

    Hirata, Takafumi; Kon, Yoshiaki

    2008-03-01

    A laser ablation-inductively coupled plasma-mass spectrometric (LA-ICPMS) technique utilizing a titanium-sapphire (TiS) femtosecond laser (fs-laser) has been developed for elemental and isotopic analysis. The signal intensity profile, depth of the ablation pit and level of elemental fractionation were investigated in order to evaluate the analytical capability of the present fs-laser ablation-ICPMS technique. The signal intensity profile of (57)Fe, obtained from iron sulfide (FeS(2)), demonstrated that the resulting signal intensity of (57)Fe achieved by the fs-laser ablation was almost 4-times higher than that obtained by ArF excimer laser ablation under a similar energy fluence (5 J/cm(2)). In fs-laser ablation, there is no significant difference in a depth of the ablation pit between glass and zircon material, while in ArF laser ablation, the resulting crater depth on the zircon crystal was almost half the level than that obtained for glass material. Both the thermal-induced and particle size-related elemental fractionations, which have been thought to be main sources of analytical error in the LA-ICPMS analysis, were measured on a Harvard 91500 zircon crystal. The resulting fractionation indexes on the (206)Pb/(238)U (f(Pb/U)) and (238)U/(232)Th (f(U/Th)) ratios obtained by the present fs-laser ablation system were significantly smaller than those obtained by a conventional ArF excimer laser ablation system, demonstrative of smaller elemental fractionation. Using the present fs-laser ablation technique, the time profile of the signal intensity of (56)Fe and the isotopic ratios ((57)Fe/(54)Fe and (56)Fe/(54)Fe) have been measured on a natural pyrite (FeS(2)) sample. Repeatability in signal intensity of (56)Fe achieved by the fs-laser ablation system was significantly better than that obtained by ArF excimer laser ablation. Moreover, the resulting precision in (57)Fe/(54)Fe and (56)Fe/(54)Fe ratio measurements could be improved by the fs-laser ablation system. The data obtained here clearly demonstrate that, even with the fundamental wavelength (NIR operating at 780 nm), the fs-laser ablation system has the potential to become a significant tool for in-situ elemental and isotopic analysis of geochemical samples including heavy minerals and metallic materials. PMID:18332541

  14. Testing of concrete by laser ablation

    DOEpatents

    Flesher, Dann J. (Benton City, WA); Becker, David L. (Kennewick, WA); Beem, William L. (Kennewick, WA); Berry, Tommy C. (Kennewick, WA); Cannon, N. Scott (Kennewick, WA)

    1997-01-01

    A method of testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed.

  15. Testing of concrete by laser ablation

    DOEpatents

    Flesher, D.J.; Becker, D.L.; Beem, W.L.; Berry, T.C.; Cannon, N.S.

    1997-01-07

    A method is disclosed for testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed. 1 fig.

  16. Mechanism of dye-enhanced enamel ablation by Alexandrite laser radiation

    NASA Astrophysics Data System (ADS)

    Esenaliev, Rinat O.; Oraevsky, Alexander A.; Motamedi, Massoud; Rastegar, Sohi; Tittel, Frank K.

    1995-05-01

    Insufficient light absorption in hard dental tissues makes laser ablation in near UV, visible or near IR spectral ranges very inefficient to be employed for tooth cavity preparations. We used deposition of a liquid absorber, indocyanine green (ICG) dye, to overcome this problem. Experiments employed Alexandrite laser anticipating that future near IR diode laser technology will replace existing medical lasers. Ablation kinetics and mechanisms for both free-running and Q-switched modes of Alexandrite laser were studied with the aim to determine optimal parameters of laser irradiation and optimal volume of the dye. Four experimental parameters were monitored during each ablation event: (1) incident laser fluence, (2) temporal profile of the laser pulse, (3) temporal profile and magnitude of laser-induced stress transients, (4) temporal profile and spectrum of plasma emission. We also examined kinetics of plume by probing ablation products with CW He-Ne laser beam. Results depicted ablation process as a complex multistage phenomenon. Two distinct stages associated with the tooth ablation are revealed in the free-running mode: (1) ablation of a dye droplet from a tooth surface by the first laser micropulse of a 250-microsecond(s) macropulse, (2) plasma mediated ablation of a melted layer of enamel produced by thermal explosion of the dye. Plasma jet formation was delayed 10-100 microsecond(s) against the beginning of free-running pulse. Ablation stages and their efficiency are defined by laser irradiation parameters, dye concentration and its total volume. In contrast, Q-switched (nanosecond) laser ablation occurs as a one stage process, and, therefore, less efficient. In addition, Q-switched mode irradiation induces shock waves amplitudes that are about an order of magnitude higher compared with that induced by the free-running irradiation. Experimental comparison of Q-switched and free-running modes of irradiation is evident in favor of free-running mode that produces a nice smooth crater without noticeable thermomechanical damage to surrounding tissues.

  17. Effect of ZrO2 Powders on the Pyrolysis of Polycarbosilanes Coating Under Laser Ablation

    NASA Astrophysics Data System (ADS)

    Cheng, Han; Chen, Zhaofeng; Tao, Jie; Yan, Bo; Li, Cong; Wang, Liangbing; Zhang, Ying; Fang, Dan; Wan, Shuicheng; Wu, Wangping

    Aircrafts hold the outstanding mastery of the sky in modern wars, however the laser beam weapons can carry out laser attacking to aircrafts. The purpose of the present paper is to research on a new type laser protective material. Polycarbosilanes (PCS)/divinylbenzene mixtures containing ZrO2 powders were brushed to the surface of the aluminum alloy plates and then cured at 150°C for 6 h. The PCS-coated plates were ablated by laser for 3 s. The phase identification of as-ablated powders was examined by X-ray diffraction. The results indicated that the as-ablated powders of cured PCS were composed of major phase ?-SiC and smaller amounts of free carbon. The PCS composite coating played a certain role of laser ablation resistance. The effect of added ZrO2 powders on the pyrolysis of PCS-coating under laser ablation is conspicuous.

  18. Deposition of potassium–oxygen on silicon surfaces by pulsed laser ablation of potassium superoxide: Study of work function changes

    Microsoft Academic Search

    Cheow-Keong Choo; Daisuke Suzawa; Katsumi Tanaka

    2006-01-01

    Potassium–oxygen species were deposited on pure, Si nanoparticles coated and H-terminated Si nanoparticles coated p-Si(100) surfaces by pulsed laser ablation of potassium superoxide (KO2) target. The deposition properties, composition and the work function changes of the deposited species were investigated in situ using an X-ray photoelectron spectroscopy (XPS) and a Kelvin probe measurement. The deposited species were assigned to K2O2

  19. Synchronized videography of plasma plume expansion during femtosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Paolasini, Steven; Kietzig, Anne

    2014-03-01

    Femtosecond lasers are gaining industrial interest for surface patterning and structuring because of the reduced heat effects to the surrounding material, resulting in a good quality product with a high aspect ratio. Analysis of the plasma plume generated during ablation can provide useful information about the laser-material interactions and thereby the quality of the resulting surface patterns. As a low-cost alternative to rather complicated ICCD camera setups, presented here is an approach based on filming the laser machining process with a high speed camera and tuning the frame rate of the camera to slightly lower than the laser pulse frequency. The delay in frequency between the laser and camera results in frames taken from sequential pulses. Each frame represents a later phase of plume expansion although taken from different pulses. Assuming equal plume evolution processes from pulse to pulse, the sequence of images obtained completes a plume expansion video. To test the assumption of homogeneity between sequential plumes, the camera can be tuned to the frequency of the laser, as to capture consecutive plumes at the same phase in their evolution. This approach enables a relatively low-cost, high resolution visualization of plasma plume evolution suitable for industrial micromachining applications with femtosecond lasers. Using this approach we illustrate differences in plume expansion at the example of machining homogeneous surface patterns in different liquid and gaseous processing environments.

  20. Morphological comparison between nano- and picosecond laser ablation in enamel

    NASA Astrophysics Data System (ADS)

    Lizarelli, Rosane F. Z.; Kurachi, Cristina; Misoguti, Lino; Bagnato, Vanderlei S.

    2000-03-01

    Human enamel tissue has been exposed to Nd:YAG pulsed laser operating in nanosecond and picosecond pulse regime. Morphological comparison between the regimes of operation have been investigated special attention to preservation of structure was taken. Trains of pulses with picosecond duration from a Q-switched and mode-locked Nd:YAG laser and pulses with nanosecond duration from a Q-switched Nd:YAG laser both operating at 15 Hz kept at in same average power, were focused in human sound molar during 30 s. Drilled holes with different morphological characteristics were observed for several laser intensity regime. Enamel surfaces were examined in a scanning electron microscope and their morphological characteristics compared. Contrast between the morphology of the enamel when treated with different powers and lasers pulse duration were observed. Picosecond pulses promote a better defined material removal while nanosecond pulses at the equivalent average power level causes a large intermediate modified region between ablated and normal tissue, as well as a complete superficial modification of the existent original structure. Results show an important correlation between the surface morphology and the pulse width of the lasers, giving indications towards the use of ultrashort laser pulses in Dentistry.

  1. Laser spectroscopy and quantum optics

    Microsoft Academic Search

    T. W. Hänsch; H. Walther

    1999-01-01

    In this paper the authors discuss recent advances and trends in laser spectroscopy and quantum optics. It is obvious that both are fields that experienced a tremendous development in the last twenty years. Therefore the survey must be incomplete, and only a few highlights are touched on.

  2. Matrix Effects on Boron Containing Materials due to Laser Ablation Molecular Isotopic Spectrometry (LAMIS)

    NASA Astrophysics Data System (ADS)

    Brown, Staci R.; Akpovo, Charlemagne A.; Martinez, Jorge; Ford, Alan; Herbert, Kenley; Johnson, Lewis

    2014-03-01

    Laser Induced Breakdown Spectroscopy (LIBS) is a spectroscopic technique that is used for the qualitative and quantitative analysis of materials in the liquid, solid, or gas phase. LIBS can also be used for the detection of isotopic shifts in atomic and diatomic species via Laser-Ablation Molecular Isotopic Spectroscopy (LAMIS). However, any additional elements that are entrained into the plasma other than the element of interest, can affect the extent of ablation and quality of spectra and hence, potentially obscure or aid in the relative abundance assessment for a given element. To address the importance of matrix effects, the isotopic analysis of boron obtained from boron oxide (BO) emission originating from different boron-containing compounds, such as boron nitride (BN), boric acid (H3BO3) , and borax (Na2B4O710H2O), via LIBS has been performed here. Each of these materials has different physical properties and elemental composition in order to illustrate possible challenges for the LAMIS method. A calibration-free model similar to that for the original LAMIS work is used to determine properties of the plasma as the matrix is changed. DTRA

  3. The effect of free-electron laser pulse structure on mid-infrared soft-tissue ablation: ablation metrics

    Microsoft Academic Search

    Mark A. Mackanos; John A. Kozub; E. Duco Jansen

    2005-01-01

    Pulsed mid-infrared (6.45 µm) radiation has been shown to cut soft tissue with minimal collateral damage (<40 µm) however, the mechanism of ablation has not been elucidated to date. The goal of this research was to examine the role of the unique pulse structure of the Vanderbilt Mark-III free-electron laser (FEL) and its role in the efficient ablation of soft

  4. The effect of free-electron laser pulse structure on mid-infrared soft-tissue ablation: ablation metrics

    Microsoft Academic Search

    Mark A Mackanos; John A Kozub; E Duco Jansen

    2005-01-01

    Pulsed mid-infrared (6.45 m) radiation has been shown to cut soft tissue with minimal collateral damage (<40 m); however, the mechanism of ablation has not been elucidated to date. The goal of this research was to examine the role of the unique pulse structure of the Vanderbilt Mark-III free-electron laser (FEL) and its role in the efficient ablation of soft

  5. Efficiency and Plume Dynamics for Mid-IR Laser Ablation of Cornea

    Microsoft Academic Search

    Aroshan Jayasinghe; Borislav Ivanov; M. Shane Hutson

    2009-01-01

    This paper reports ablation experiments on porcine corneal tissue using the Vanderbilt Mark III Free Electron Laser (FEL) and a tabletop Raman-shifted Alexandrite laser. These experiments were designed to test previous models that suggested wavelength and intensity dependent ablation mechanisms. In one test, we compare ablation efficiency and plume dynamics for two FEL wavelengths (lambda=2.77, 6.45 mum) chosen such that

  6. Particle Generation by Ultraviolet-Laser Ablation during Surface Decontamination

    SciTech Connect

    Cheng, Mengdawn [ORNL

    2006-01-01

    A novel photonic decontamination method was developed by removal of pollutants from material surfaces. Such a method relies on the ability of a high-energy laser beam to ablate materials from a contaminated surface layer, thus producing airborne particles. In this paper, the authors presented the results obtained using a scanning mobility particle sizer (SMPS) system and an aerosol particle sizer (APS). Particles generated by laser ablation from the surfaces of cement, chromium-embedded cement, and alumina were experimentally investigated. Broad particle distributions from nanometer to micrometer in size were measured. For stainless steel, virtually no particle >500 nm in aerodynamic size was detected. The generated particle number concentrations of all three of the materials were increased as the 266-nm laser fluence (milijoules per square centimeter) increased. Among the three materals tested, cement was found to be the most favorable for particle removal, alumina next, and stainless steel the least. Chromium (dropped in cement) showed almost no effects on particle production. For all of the materials tested except for stainless steel, bimodal size distributions were observed; a smaller mode peaked at ~50-70 nm was detected by SMPS and a larger mode (peaked at ~0.70-0.85 m) by APS. Based on transmission electron microscopy observations, the authors concluded that particles in the range of 50-70 nm were aggregates of primary particles, and those of size larger than a few hundred nanometers were produced by different mechanisms, for example, massive object ejection from the material surfaces.

  7. Organic semiconductor distributed feedback laser fabricated by direct laser interference ablation

    NASA Astrophysics Data System (ADS)

    Stroisch, Marc; Woggon, Thomas; Lemmer, Uli; Bastian, Georg; Violakis, Georg; Pissadakis, Stavros

    2007-04-01

    We use a pulsed, frequency tripled picosecond Nd:YAG laser for holographic ablation to pattern a surface relief grating into an organic semiconductor guest-host system. The resulting second order distributed feedback lasers exhibit laser action with laser thresholds being comparable to those obtained with resonators structured by standard lithographic techniques. The details of the interference ablation of tris-(8-hydroxyquinoline) aluminum (Alq3) doped with the laser dye 4- dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) are presented and discussed. Lasing action is demonstrated at a wavelength of 646.6 nm, exploiting second order Bragg reflection in a relief grating with a period of 399 nm.

  8. Improved analytical characterization of solid waste-forms by fundamental development of laser ablation technology. 1998 annual progress report

    SciTech Connect

    Russo, R.E.

    1998-06-01

    'This EMSP research endeavors to understand fundamental laser-ablation sampling processes and to determine the influence of these processes on analytical characterization of EM waste-site samples. The issues germane to the EMSP are sensitivity and accuracy of analysis. These issues are researched by studying fractionation, sample transport, mass loading, and analytical system optimization. Inductively coupled plasma-mass spectroscopy (ICP-MS) is emphasized in this research because of its use throughout the DOE labs and sites. This report summarizes research performed over the first half of this three-year program. Four issues were emphasized to improve analytical sensitivity and accuracy, including the time dependent laser removal of mass from a solid sample, fractionation, particle generation and transport, and optimization of the ICP-MS for laser ablation sampling. This research has led to six journal publications.'

  9. Femtosecond laser ablation of indium tin-oxide narrow grooves for thin film solar cells

    E-print Network

    Van Stryland, Eric

    Femtosecond laser ablation of indium tin-oxide narrow grooves for thin film solar cells Qiumei Bian in revised form 15 June 2012 Accepted 18 June 2012 Keywords: Ablation Femtosecond laser Indium tin oxide a b s t r a c t Finding ways to scribe indium-tin oxide (ITO) coating plays an important role

  10. Brief Communication Ultra fine carbon nitride nanocrystals synthesized by laser ablation

    E-print Network

    Bristol, University of

    Brief Communication Ultra fine carbon nitride nanocrystals synthesized by laser ablation in liquid, University of Bristol, CantockÕs Close, Bristol, BS8 1TS, UK; 2 Department of Aero- space Engineering form 15 October 2006 Key words: carbon nitride, laser ablation, liquid-solid interface, nanoparticle

  11. Urethroscopic holmium: YAG laser ablation for acquired posterior urethral diverticulum after repair of anorectal malformations.

    PubMed

    Takazawa, Shinya; Uchida, Hiroo; Kawashima, Hiroshi; Tanaka, Yujiro; Masuko, Takayuki; Deie, Kyoichi; Amano, Hizuru; Kobayashi, Kenichiro; Tada, Minoru; Iwanaka, Tadashi

    2014-09-01

    Two patients with acquired posterior urethral diverticulum that is a complication of laparoscopic assisted anorectoplasty underwent urethroscopic holmium: YAG laser ablation. After the ablation therapies, the size of the diverticulum markedly decreased in both patients. Holmium: YAG laser is safe and easy to handle in the small pediatric urethra. PMID:25062769

  12. Real-time measurement of ArF excimer laser corneal tissue ablation rates using cross-

    E-print Network

    Hahn, David W.

    Real-time measurement of ArF excimer laser corneal tissue ablation rates using cross- correlation of bovine cornea over a range of clinically relevant laser fluences. A linear relationship was observed between several cross-correlation metrics and the directly measured corneal ablation rate, yielding

  13. Measurement of depth profile of hydrogen isotope atom contained in solid material using resonant laser ablation

    Microsoft Academic Search

    Masafumi Yorozu; Yasuhiro Okada; Terunobu Nakajyo; Akira Endo

    1999-01-01

    The depth profile of hydrogen isotope atoms was measured by using mass spectrometry combined with resonant laser ablation. A graphite sample was implanted with deuterium by a cyclotron and was employed for the measurements. The graphite sample was ablated by a tunable laser which wavelength was corresponding to the resonant wavelength of 1S - 2S for deuterium with two- photon

  14. Determination of intratest variability of trace elements in foraminifera by laser ablation inductively coupled

    E-print Network

    Demouchy, Sylvie

    inductively coupled plasma-mass spectrometry E. C. Hathorne, O. Alard, R. H. James, and N. W. Rogers, Mg, Mn, Cu, Zn, Sr and Ba) within foraminifera tests using laser ablation inductively coupled plasma of trace elements in foraminifera by laser ablation inductively coupled plasma-mass spectrometry, Geochem

  15. Laser Ablation Electrospray Ionization for Atmospheric Pressure Molecular Imaging Mass Spectrometry

    E-print Network

    Vertes, Akos

    -IR) MALDI (3), laser ablation S.S. Rubakhin, J.V. Sweedler (eds.), Mass Spectrometry Imaging, MethodsChapter 9 Laser Ablation Electrospray Ionization for Atmospheric Pressure Molecular Imaging Mass method for the direct imaging of biological tis- sues by mass spectrometry. By performing ionization

  16. Laser Ablation (LA-ICPMS) at the Institute of Mineralogy, University of WÃrzburg

    NSDL National Science Digital Library

    University of W& uuml Institute of Mineralogy

    This website from the University of Wuerzburg briefly describes laser ablation, the most versatile in-situ solid sampling technique for ICP mass spectrometry. The website also features a section detailing applications for laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), including trace element concentration and chemical zoning, and others.

  17. Production and acceleration of ion beams by laser ablation.

    PubMed

    Velardi, L; Siciliano, M V; Delle Side, D; Nassisi, V

    2012-02-01

    In this work, we present a new pulsed laser ablation technique to obtain energetic ion beams. The accelerator we made is a compact device able to extract and accelerate the ionic components of plasma up to 160 keV per charge state. It is composed by a generating chamber containing an expansion chamber used like first electrode. Next, a second electrode connected to ground and a third electrode connected to negative voltage are used. The third electrode is used also as Faraday cup. By the analysis of the ion signals we studied the plume parameters such as TOF accelerated signals, charge state, and divergence. PMID:22380322

  18. Production and acceleration of ion beams by laser ablation

    SciTech Connect

    Velardi, L.; Siciliano, M. V.; Delle Side, D.; Nassisi, V. [Department of Physics and I.N.F.N., LEAS Laboratory, University of Salento, Via Provinciale Lecce-Monteroni, 73100 Lecce (Italy)

    2012-02-15

    In this work, we present a new pulsed laser ablation technique to obtain energetic ion beams. The accelerator we made is a compact device able to extract and accelerate the ionic components of plasma up to 160 keV per charge state. It is composed by a generating chamber containing an expansion chamber used like first electrode. Next, a second electrode connected to ground and a third electrode connected to negative voltage are used. The third electrode is used also as Faraday cup. By the analysis of the ion signals we studied the plume parameters such as TOF accelerated signals, charge state, and divergence.

  19. Towards redistribution laser cooling of molecular gases: Production of candidate molecules SrH by laser ablation

    E-print Network

    Simon, Philipp; Weller, Lars; Sass, Anne; Weitz, Martin; 10.1117/12.2002379

    2013-01-01

    Laser cooling by collisional redistribution of radiation has been successfully applied in the past for cooling dense atomic gases. Here we report on progress of work aiming at the demonstration of redistribution laser cooling in a molecular gas. The candidate molecule strontium monohydride is produced by laser ablation of strontium dihydride in a pressurized noble gas atmosphere. The composition of the ablation plasma plume is analyzed by measuring its emission spectrum. The dynamics of SrH molecular density following the ablation laser pulse is studied as a function of the buffer gas pressure and the laser intensity.

  20. An observation of ablation effect of soft biotissue by pulsed Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Zhang, Xianzeng; Xie, Shusen; Ye, Qing; Zhan, Zhenlin

    2007-02-01

    Because of the unique properties with regard to the absorption in organic tissue, pulsed Er:YAG laser has found most interest for various application in medicine, such as dermatology, dentistry, and cosmetic surgery. However, consensus regarding the optimal parameters for clinical use of this tool has not been reached. In this paper, the laser ablation characteristics of soft tissue by Er:YAG laser irradiation was studied. Porcine skin tissue in vitro was used in the experiment. Laser fluences ranged from 25mJ/mm2 to 200mJ/mm2, repetition rates was 5Hz, spot sizes on the tissue surface was 2mm. The ablation effects were assessed by the means of optical microscope, ablation diameters and depths were measured with reading microscope. It was shown that the ablation of soft biotissue by pulsed Er:YAG laser was a threshold process. With appropriate choice of irradiation parameters, high quality ablation with clean, sharp cuts following closely the spatial contour of the incident beam can be achieved. The curves of ablation crater diameter and depth versus laser fluence were obtained, then the ablation threshold and ablation yield were calculated subsequently, and the influence of the number of pulses fired into a crater on ablation crater depth was also discussed.

  1. Picosecond laser ablation of poly-L-lactide: Effect of crystallinity on the material response

    SciTech Connect

    Ortiz, Rocio; Quintana, Iban; Etxarri, Jon [Manufacturing Processes Department, Fundacion TEKNIKER, Av. Otaola 20, 20600, Eibar, Guipuzcoa (Spain); Lejardi, Ainhoa; Sarasua, Jose-Ramon [Department of Mining and Metallurgy Engineering and Materials Science, School of Engineering, University of the Basque Country (EHU-UPV), Alameda de Urquijo s/n, 48013 Bilbao (Spain)

    2011-11-01

    The picosecond laser ablation of poly-L-lactide (PLLA) as a function of laser fluence and degree of crystallinity was examined. The ablation parameters and the surface modifications were analyzed under various irradiation conditions using laser wavelengths ranging from the ultraviolet through the visible. When processing the amorphous PLLA, both energy threshold and topography varied considerably depending on laser wavelength. Laser irradiation showed a reduction in the energy ablation threshold as the degree of crystallinity increased, probably related to photomechanical effects involved in laser ablation with ultra-short pulses and the lower stress accommodation behavior of semicrystalline polymers. In particular, cooperative chain motions are impeded by the higher degree of crystallinity, showing fragile mechanical behavior and lower energy dissipation. The experimental results on ablation rate versus laser energy showed that UV laser ablation on semicrystalline PLLA was more efficient than the visible ablation, i.e., it exhibits higher etch rates over a wide range of pulse energy conditions. These results were interpreted in terms of photo-thermal and photo-chemical response of polymers as a function of material micro-structure and incident laser wavelength. High quality micro-grooves were produced in amorphous PLLA, reveling the potential of ultra-fast laser processing technique in the field of micro-structuring biocompatible and biodegradable polymers for biomedical applications.

  2. Laser ablative cutting of ceramics for electronics applications

    SciTech Connect

    Warner, B. E., LLNL

    1996-03-01

    Pulsed, high-beam quality lasers offer unique materials processing characteristics. In processing metals, copper vapor and pulsed Nd:YAG lasers have produced micron-scale cuts and holes with submicron heat-affected zones. Since the cost of laser photons is high and average material removal rates can be slow with ablation, high value-added applications are necessary to justify processing costs. Ceramics present a special challenge for manufacturing because of their high hardness, relatively low thermal conductivity, and brittle nature. Surface damage typically limits the strength of a ceramic part to a small fraction of its bulk strength. This work investigates the use of copper vapor and pulsed diode-pumped Nd:YAG lasers to cut precision features in ceramic substrates. Variations in laser wavelength and power, processing speed, ceramic type, and assist gas were investigated with the goal of producing <100-{mu}m wide by 600-{mu}m deep cuts through silicon-carbide and alumina/titanium-carbide substrates for potential use in electronics. Silicon-carbide bars 250-{mu}m wide by 600-{mu}m high by 2.5-cm long were laser cut from substrates without fracture.

  3. Glow-discharge-assisted laser-induced breakdown spectroscopy: increased sensitivity in solid analysis.

    PubMed

    Tereszchuk, K A; Vadillo, J M; Laserna, J J

    2008-11-01

    A glow discharge operating in steady-state and pulsed temporal conditions is used to excite the material previously excited by a pulsed laser ablation system. The system provides a simple means by which to potentially excite the material ablated by the incident laser pulse by taking advantage of enhanced collisional excitation. In this way, one can effectively reduce laser pulse energies below the excitation and ionization thresholds to potentially those required solely for laser ablation of the material, reducing sample damage and improving the lateral resolution. Several critical parameters such as the gas pressure, gas type, and discharge voltage were evaluated, demonstrating the potential of the technique for spatially resolved analysis. The new dual glow-discharge laser-induced breakdown spectroscopy (GD-LIBS) synchronous scheme provides significant signal enhancements when compared to LIBS or GD under identical conditions. PMID:19007470

  4. Ultra-fast movies of thin-film laser ablation

    NASA Astrophysics Data System (ADS)

    Domke, Matthias; Rapp, Stephan; Schmidt, Michael; Huber, Heinz P.

    2012-11-01

    Ultra-short-pulse laser irradiation of thin molybdenum films from the glass substrate side initiates an intact Mo disk lift off free from thermal effects. For the investigation of the underlying physical effects, ultra-fast pump-probe microscopy is used to produce stop-motion movies of the single-pulse ablation process, initiated by a 660-fs laser pulse. The ultra-fast dynamics in the femtosecond and picosecond ranges are captured by stroboscopic illumination of the sample with an optically delayed probe pulse of 510-fs duration. The nanosecond and microsecond delay ranges of the probe pulse are covered by an electronically triggered 600-ps laser. Thus, the setup enables an observation of general laser ablation processes from the femtosecond delay range up to the final state. A comparison of time- and space-resolved observations of film and glass substrate side irradiation of a 470-nm molybdenum layer reveals the driving mechanisms of the Mo disk lift off initiated by glass-side irradiation. Observations suggest that a phase explosion generates a liquid-gas mixture in the molybdenum/glass interface about 10 ps after the impact of the pump laser pulse. Then, a shock wave and gas expansion cause the molybdenum layer to bulge, while the enclosed liquid-gas mixture cools and condenses at delay times in the 100-ps range. The bulging continues for approximately 20 ns, when an intact Mo disk shears and lifts off at a velocity of above 70 m/s. As a result, the remaining hole is free from thermal effects.

  5. Single molecule laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Atta, Diaa; Okasha, Ali

    2015-01-01

    In this article, we discussed some single molecule spectroscopy techniques and methods. We have chosen the simplicity in this survey based on our laboratory experience in this field. We concentrated on the imaging by both techniques the wide field and the scanning microscopes. Other imaging enhancements on the technique like extended resolution wide field, the total internal reflection imaging, and its derivatives are also reviewed. In addition to the imaging techniques, some diffusion techniques also are discussed like fluorescence correlation spectroscopy. The related methods like Forester resonance transfer, photo-induced electron transfer and anisotropy (steady state and time decay) are also discussed. In addition, we elucidated some simple details about the theory behind the FCS and its resulting curve fitting. This review is preceded by general introduction and ended with the conclusion.

  6. Calibration free laser-induced breakdown spectroscopy of oxide materials

    NASA Astrophysics Data System (ADS)

    Praher, B.; Palleschi, V.; Viskup, R.; Heitz, J.; Pedarnig, J. D.

    2010-08-01

    The quantitative determination of oxide concentration by laser-induced breakdown spectroscopy is relevant in various fields of applications (e.g.: analysis of ores, concrete, slag). Calibration free laser-induced breakdown spectroscopy and the multivariate calibration are among the methods employed for quantitative concentration analysis of complex materials. We measured the intensity of neutral and ionized atomic emission lines of oxide materials by laser-induced breakdown spectroscopy and we modified the calibration free laser-induced breakdown spectroscopy method to increase the accuracy. The concentration of oxides was obtained by using stoichiometric relations. Sample materials were prepared from oxide powder (Fe 2O 3, MgO, CaO) by mixing and pressing. The concentration was 9.8-33.3 wt.% Fe 2O 3, 7.6-33.3 wt.% MgO and 33.3-81.2 wt.% CaO for different samples. Nd:YAG laser (wavelength 1064 nm, pulse duration ? 6 ns) ablation was performed in air. The laser-induced plasma emission was measured by an Echelle spectrometer equipped with a sensitivity calibrated ICCD camera. The numerical calibration free laser-induced breakdown spectroscopy algorithm included the fast deconvolution of instrumental function, and the correction of self-absorption effects. The oxide concentration CCF calculated from calibration free laser-induced breakdown spectroscopy results and the nominal concentration CN were very close for all samples investigated. The relative error in concentration, | CCF- CN|/ CN, was < 10%, < 20%, and < 5% for Fe 2O 3, MgO, and CaO, respectively. The results indicate that this method can be employed for the analysis of major elements in multi-component technical materials.

  7. Antibacterial activity of magnetic iron oxide nanoparticles synthesized by laser ablation in liquid.

    PubMed

    Ismail, Raid A; Sulaiman, Ghassan M; Abdulrahman, Safa A; Marzoog, Thorria R

    2015-08-01

    In this study, (50-110nm) magnetic iron oxide (?-Fe2O3) nanoparticles were synthesized by pulsed laser ablation of iron target in dimethylformamide (DMF) and sodium dodecyl sulfate (SDS) solutions. The structural properties of the synthesized nanoparticles were investigated by using Fourier Transform Infrared (FT-IR) spectroscopy, UV-VIS absorption, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). The effect of laser fluence on the characteristics of these nanoparticles was studied. Antibacterial activities of iron oxide nanoparticles were tested against Gram-positive; Staphylococcus aureus and Gram-negative; Escherichia coli, Pseudomonas aeruginosa and Serratia marcescens. The results showed a noteworthy inhibition on both bacterial strains. The preparation conditions were found to affect significantly the antibacterial activity of these nanoparticles. The synthesized magnetic nanoparticles were used to capture rapidly S. aureus bacteria under the magnetic field effect. PMID:26042717

  8. Surface modification of Ti6Al4V by nanosecond laser ablation for biomedical applications

    NASA Astrophysics Data System (ADS)

    Fiorucci, M. P.; López, A. J.; Ramil, A.

    2015-04-01

    This paper presents the surface textured process of biometal Ti6Al4V by means of 355 nm Nd:YVO4 nanosecond laser. Our target is to create structures with sizes which favour osseointegration. In this work a pattern of parallel grooves was generated after a deep analysis of the irradiation parameters involved. Ablation modifies not only the topography but also physico-chemical properties of the metal surface. Changes in the morphology and the physico-chemical state of the laser induced groove pattern were studied by a scanning electron microscopy, X-ray diffraction and X- ray photoelectron spectroscopy, which revealed, among others, an increase of micro roughness and a oxide layer entirely formed by TiO2, which can improve biocompatibility properties of the textured surface.

  9. Stable isotope laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Becker, J. F.; Yaldaei, Ramil; Mckay, Christopher P.

    1989-01-01

    Recent advances in semiconductor laser technology have produced a reliable lightweight device ideally suited for a spacecraft high resolution molecular spectrometer. Lead-salt tunable diode lasers (TDL) emit in several spectral modes, each with a very narrow linewidth of -0.0003/cm. This spectral resolution is much narrower than typical Doppler broadened molecular linewidths in the mid-IR range. Thus it is possible to detect individual rotational lines within the vibrational band and measure their intensity, which can be used to determine gas concentration. The narrow spectral lines of any impurity gas tend to lie between the narrow lines of the gas of interest. This represents a major advantage over the accepted gas chromatograph mass spectrometer (GCMS) technique for measuring gas concentrations and isotope ratios. The careful and extensive gas purification procedures required to remove impurities for reliable GCMS measurements will not be required for an IR laser gas analysis. The infrared laser gas analysis technique is being developed to measure stable isotopic ratios of gases such as CO2, CH4, N2O, and NH3. This will eventually lead to development of instruments capable of in situ istopic measurements on planets such as Mars. The carbon (C-12, C-13) isotope ratio is indicative of the type of carbon fixation mechanisms (e.g., photosynthesis, respiration) in operation on a planet, while the nitrogen (N-14, N-15) isotope ratio can probably be used to date nitrogen-bearing Martian samples. The absorbance ratio of two adjacent lines of CO2 in the 2300/cm (4.3 micron) region of the spectrum was measured. The precision of the measurement is presently better than 1 percent and significant improvement is anticipated as rapid sweep-integration techniques and computer controlled data acquistion capabilities are incorporated.

  10. Morphological features of silicon substrate by using different frequency laser ablation in air and water

    NASA Astrophysics Data System (ADS)

    Xu, J. Y.; Hu, H.; Lei, Y. L.

    2014-10-01

    The interaction of the nanosecond laser (FWHM = 30 ns, ? = 355 nm) and monocrystalline silicon is investigated in air and water. Conventional optical and scanning electron microscopes are used to characterize surface ablation of the monocrystalline silicon. A numerical model is used to ascertain the time of the bubble motion in water. Morphological features of the laser-induced crater are different under various environments and frequencies. More debris is found when using high frequency ablation, and a larger zone is affected by heat when using low frequency ablation in air. There is no debris found in water, and the morphology of craters is better in low frequency ablation than that in high frequency ablation because bubbles generated by high frequency ablation affect laser transmission.

  11. Single-shot ablation threshold of chromium using UV femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Banerjee, S. P.; Fedosejevs, R.

    2014-07-01

    Single-shot ablation threshold for thin chromium film was studied using 266 nm, femtosecond laser pulses. Chromium is a useful material in the nanotechnology industry and information on ablation threshold using UV femtosecond pulses would help in precise micromachining of the material. The ablation threshold was determined by measuring the ablation crater diameters as a function of incident laser pulse energy. Absorption of 266 nm light on the chromium film was also measured under our experimental conditions, and the absorbed energy single-shot ablation threshold fluence was 46 ± 5 mJ/cm2. The experimental ablation threshold fluence value was compared to time-dependent heat flow calculations based on the two temperature model for ultrafast laser pulses. The model predicts a value of 31.6 mJ/cm2 which is qualitatively consistent with the experimentally obtained value, given the simplicity of the model.

  12. Quantitative determination of element concentrations in industrial oxide materials by laser-induced breakdown spectroscopy

    Microsoft Academic Search

    B. Praher; R. Rössler; E. Arenholz; J. Heitz; J. D. Pedarnig

    Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) method is employed for quantitative determination of oxide\\u000a concentrations in multi-component materials. Industrial oxide materials from steel industry are laser ablated in air, and\\u000a the optical plasma emission is collected by spectrometers and gated detectors. The temperature and electron number density\\u000a of laser-induced plasma are determined from measured LIBS spectra. Emission lines of aluminium (Al),

  13. In situ analysis of steel under reduced ambient pressure by laser-induced breakdown spectroscopy

    Microsoft Academic Search

    Johannes Heitz; Johann Gruber; Nikita Arnold; Dieter Bäuerle; Norbert Ramaseder; Wilfried Meyer; Johann Hochörtler

    2003-01-01

    We report on rapid in-situ analysis of liquid and solid steel samples under reduced ambient pressure by laser-induced breakdown spectroscopy (LIBS) using a transportable system. LIBS denotes a technique where a pulsed laser beam is used to ablate small amounts of the target material. The characteristic optical emission line intensities of the excited species in the laser-generated plasma plume allow

  14. Silicon and zinc telluride nanoparticles synthesized by pulsed laser ablation: Size distributions and nanoscale structure

    SciTech Connect

    Lowndes, D.H.; Rouleau, C.M.; Duscher, G. [and others

    1997-08-01

    Size distributions of Si and ZnTe nanoparticles produced by low energy density ArF (193 nm) pulsed laser ablation into ambient gases were measured as a function of the gas pressure and target-substrate separation, D{sub ts}, using atomic force microscopy (AFM) and high resolution scanning electron microscopy (HRSEM). For low energy density (Ed = 1.04 J/cm{sup 2}) ablation of Si into He at pressures of 0.5, 1.5, 4 and 10 torr, large nanoparticles were most numerous at D{sub ts} = 10 mm, with smaller nanoparticles found at 20 mm and 40 mm. For each D{sub ts} value a maximum of the mean nanoparticle diameter occurred for a He pressure near 6 torr, in contrast to other recent measurements in which the size of Si nanoparticles increased monotonically with the He pressure. High resolution Z-contrast transmission electron microscopy (HRZTEM) and electron energy loss spectroscopy (EELS) revealed that ZnTe nanoparticles formed by ablation into nitrogen at E{sub d} = 0.74 J/cm{sup 2} consisted of a crystalline ZnTe core surrounded by an amorphous ZnO shell. Growth defects and surface steps were clearly visible in the ZnTe crystalline core. The dependences of the mean diameter of ZnTe nanocrystals on nitrogen pressure and D{sub ts}, were qualitatively similar to those found for Si in He.

  15. Synthesis of oxidation resistant lead nanoparticle films by modified pulsed laser ablation

    SciTech Connect

    Shin, Eunsung; Murray, P. Terrence; Subramanyam, Guru; Malik, Hans K.; Schwartz, Kenneth L. [Research Institute, University of Dayton, Dayton, OH 45469-0170 (United States); Research Institute, University of Dayton, Dayton, OH 45469-0170, USA and Graduate Materials Engineering, University of Dayton, Dayton, OH 45469-0240 (United States); Department of Electrical and Computer Engineering, University of Dayton, Dayton, OH 45469-0232 (United States); Northrop Grumman Electronic Systems, Linthicum, MD 21090 (United States)

    2012-07-30

    Thin layers of lead nanoparticles have been produced by a modified pulsed laser ablation (PLA) process in which smaller nanoparticles were swept out of the ablation chamber by a stream of flowing Ar. Large ({mu}m-sized) particles, which are usually deposited during the standard PLA process, were successfully eliminated from the deposit. The nanoparticles deposited on room temperature substrates were well distributed, and the most probable particle diameter was in the order of 30 nm. Since lead is highly reactive, the nanoparticles formed in Ar were quickly oxidized upon exposure to air. A small partial pressure of H{sub 2}S gas was subsequently added to the effluent, downstream from the ablation chamber, and this resulted in the formation of nanoparticle deposits that were surprisingly oxidation resistant. The properties of the nanoparticle films (as determined by transmission electron microscopy, scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and conductivity measurements) are reported, and the mechanism of the oxidation retardation process is discussed.

  16. Saturation of perturbation growth in ablatively driven planar laser targets

    NASA Astrophysics Data System (ADS)

    Velikovich, Alexander L.; Dahlburg, Jill P.; Gardner, John H.; Taylor, Robert J.

    1998-05-01

    Saturation of the mass variation growth during the shock transit time, theoretically predicted for the surface roughness case by Ishizaki and Nishihara [Phys. Rev. Lett. 78, 1920 (1997)] and for the laser imprint case by Taylor et al. [Phys. Rev. Lett. 79, 1861 (1997)], is studied analytically and numerically. The saturation is demonstrated to be essentially the same effect in both cases, caused by the stabilizing action of mass ablation. Scalings of saturation time and saturation level for the two cases are related. For lower-density foam targets, the peak level of mass variation is proportional approximately to ?01/2 and exactly to ?0 for the cases of laser imprint and surface roughness, respectively.

  17. Neutral atomic jet generation by laser ablation of copper targets

    SciTech Connect

    Matos, J. B. de; Rodrigues, N. A. S. [Department of Physics, Technological Institute for Aeronautics – ITA/DCTA, São José dos Campos, P.O. Box 6050, 12.228-900 Sao Paulo (Brazil); Destro, M. G.; Silveira, C. A. B. da [Photonics Division, Institute for Advanced Studies – IEAv/DCTA, São José dos Campos, P.O. Box 6044, 12.231-970 Sao Paulo (Brazil)

    2014-08-15

    This work aimed the obtainment of a neutral atomic jet departing from a plume generated by laser ablation of copper targets. A pair of electrodes together with a transducer pressure sensor was used to study the ablated plume charge composition and also to measure the ion extraction from the plasma plume. The neutral beam was produced with this setup and the relative abundance of neutrals in the plasma was measured, it decreases from 30% to 8% when the laser fluence is varied from 20 J/cm{sup 2} to 32 J/cm{sup 2}. The necessary voltage to completely remove the ions from the plume varied from 10 V to 230 V in the same fluence range. TOF analysis resulted in center of mass velocities between 3.4 and 4.6 km/s, longitudinal temperature in the range from 1 × 10{sup 4} K to 2.4 × 10{sup 4} K and a Mach number of M = 2.36, calculated using purely hydrodynamic expansion approximation.

  18. Neutral atomic jet generation by laser ablation of copper targets.

    PubMed

    de Matos, J B; Destro, M G; da Silveira, C A B; Rodrigues, N A S

    2014-08-01

    This work aimed the obtainment of a neutral atomic jet departing from a plume generated by laser ablation of copper targets. A pair of electrodes together with a transducer pressure sensor was used to study the ablated plume charge composition and also to measure the ion extraction from the plasma plume. The neutral beam was produced with this setup and the relative abundance of neutrals in the plasma was measured, it decreases from 30% to 8% when the laser fluence is varied from 20 J/cm(2) to 32 J/cm(2). The necessary voltage to completely remove the ions from the plume varied from 10 V to 230 V in the same fluence range. TOF analysis resulted in center of mass velocities between 3.4 and 4.6 km/s, longitudinal temperature in the range from 1 × 10(4) K to 2.4 × 10(4) K and a Mach number of M = 2.36, calculated using purely hydrodynamic expansion approximation. PMID:25173267

  19. Skin-tightening effect of fractional lasers: comparison of non-ablative and ablative fractional lasers in animal models.

    PubMed

    Park, Seung-Ha; Kim, Deok-Woo; Jeong, Taewon

    2012-10-01

    This experimental study was performed to demonstrate the effects of non-ablative fractional laser (NAFL) and ablative fractional laser (AFL). Twenty male Sprague-Dawley rats were used for the study. Three 2×2-cm-sized squares were tattooed on the abdomen of the animals. Each tattooed square was used for NAFL, AFL and control experiments. The NAFL and AFL treatment were performed with the same total energy of 12,000 mJ cm(-2). The laser treatments consisted of four sessions, with an interval of 3 weeks between sessions. The areas of tattooed skin were serially measured, and skin samples were obtained for histologic examination after 4 months of treatment. NAFL did not cause immediate skin shrinkage, but the size of the NAFL-treated skin was reduced by 4.3% after 4 months. In contrast, AFL caused immediate skin shrinkage (11.5% reduction), and the size was maintained at 9% reduction after 4 months. In histologic examination, the dermal collagen was arranged flat and parallel to the skin surface in the upper dermis, and regenerated collagen fibres were clearly noticed in both NAFL-and AFL-treated skin samples. Immunohistochemical stains showed well-regenerated type I and III collagen fibres. Western blot analysis of skin samples showed that type I/III collagen ratio was not significantly changed after fractional laser treatment. Electron microscopic studies aimed to evaluate the long-term micro-architecture of the collagen fibrils. AFL treatment reduced D-band periodicity by 5.2% and fibril diameter by 14.8%, although there was no statistically significant difference (p>0.05). Fractional laser treatment shrinks the skin surface area and regenerates collagen. The AFL treatment showed more profound skin changes than NAFL. PMID:22633871

  20. RESONANCE LASER ABLATION WITH AN OPTICAL PARAMETRIC OSCILLATOR LASER AND DETECTION BY A

    E-print Network

    Michel, Robert G.

    -red respectively. Excimer Laser Ablation for Microwave Induced Plasma Emission Spectrometry Instrumentation2 in a solid steel sample. Atomic emission signals in the Microwave Induced Plasma were enhanced by factors for its potential as an approach to solid sampling for atomic emission spectrometry (Figure 2). Operating

  1. 3D photomechanical model of tooth enamel ablation by Er-laser radiation

    NASA Astrophysics Data System (ADS)

    Belikov, Andrey V.; Shatilova, Ksenia V.; Skrypnik, Alexei V.

    2014-02-01

    The three-dimensional (3D) photomechanical model of human tooth enamel ablation is described. It takes into account: the structural peculiarities of enamel, Er-laser beam energy spatial distribution and laser radiation attenuation in the tissue. Dynamics change of enamel coefficient of absorption during ablation is also discussed. We consider the 3D photomechanical model of incomplete removal (modification) of the enamel rods by the pressure of water contained in the enamel pores and heated by laser radiation, and complete removal (ablation) of the enamel rods as result of hydroxyapatite heated by laser radiation and evaporation. Modeling results are in close agreement with the experimental results.

  2. Fabrication of polymer waveguides by laser ablation using a 355 nm wavelength Nd:YAG laser

    Microsoft Academic Search

    Paul P. Conway; David A. Hutt; David R. Selviah; Kai Wang; Jeremy Rygate; Jonathan Calver; Witold Kandulski

    2011-01-01

    The demand for optical waveguides integrated into Printed Circuit Boards (PCBs) is increasing as the limitations of copper interconnects are being reached. Optical polymer materials offer a good solution due to their relatively low cost and compatibility with traditional PCB manufacturing processes. Laser ablation is one method of manufacture, for which excimer lasers have been used, butUV Nd:YAG (Neodymium-doped Yttrium

  3. On the structure of quasi-stationary laser ablation fronts in strongly radiating plasmas

    NASA Astrophysics Data System (ADS)

    Basko, M. M.; Novikov, V. G.; Grushin, A. S.

    2015-05-01

    The effect of strong thermal radiation on the structure of quasi-stationary laser ablation fronts is investigated under the assumption that all the laser flux is absorbed at the critical surface. Special attention is paid to adequate formulation of the boundary-value problem for a steady-state planar ablation flow. The dependence of the laser-to-x-ray conversion efficiency ? r on the laser intensity IL and wavelength ?L is analyzed within the non-equilibrium diffusion approximation for radiation transfer. The scaling of the main ablation parameters with IL and ?L in the strongly radiative regime 1 - ? r ? 1 is derived. It is demonstrated that strongly radiating ablation fronts develop a characteristic extended cushion of "radiation-soaked" plasma between the condensed ablated material and the critical surface, which can efficiently suppress perturbations from the instabilities at the critical surface.

  4. Laser ablation mechanism of transparent layers on semiconductors with ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Rublack, Tino; Hartnauer, Stefan; Mergner, Michael; Muchow, Markus; Seifert, Gerhard

    2011-12-01

    Transparent dielectric layers on semiconductors are used as anti-reflection coatings both for photovoltaic applications and for mid-infrared optical elements. We have shown recently that selective ablation of such layers is possible using ultrashort laser pulses at wavelengths being absorbed by the semiconductor. To get a deeper understanding of the ablation mechanism, we have done ablation experiments for different transparent materials, in particular SiO2 and SixNy on silicon, using a broad range of wavelengths ranging from UV to IR, and pulse durations between 50 and 2000 fs. The characterization of the ablated regions was done by light microscopy and atomic force microscopy (AFM). Utilizing laser wavelengths above the silicon band gap, selective ablation of the dielectric layer without noticeable damage of the opened silicon surface is possible. In contrast, ultrashort pulses (1-2 ps) at mid-infrared wavelengths already cause damage in the silicon at lower intensities than in the dielectric layer, even when a vibrational resonance (e.g. at ? = 9.26 ?m for SiO2) is addressed. The physical processes behind this, on the first glance counterintuitive, observation will be discussed.

  5. Atomistic investigation of ablation of amorphous polystyrene under femtosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Huang, YanHua; Song, ChengWei; Zhang, JunJie; Sun, Tao

    2015-03-01

    In the present work we elucidate the thermodynamic mechanisms of femtosecond (fs) laser ablation of amorphous polystyrene by means of molecular dynamics (MD) simulations. The effects of extrinsic parameter of laser pulse intensity and intrinsic parameter of molecular architecture on the laser ablation are further studied. Simulation results show that the laser ablation-induced polymeric material removal is achieved by evaporation from the surface and expansion within the bulk. Furthermore, inter-chain sliding and intra-chain change also play important roles in the microscopic deformation of the material. It is found that both the laser pulse intensity and the arrangement of phenyl groups have significant influence on the fs laser ablation of polystyrene.

  6. Low-order harmonic generation in metal ablation plasmas in nanosecond and picosecond laser regimes

    SciTech Connect

    Lopez-Arias, M. [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Unidad Asociada Departamento de Quimica Fisica I, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid, and Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain); Oujja, M.; Sanz, M.; Castillejo, M. [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Ganeev, R. A.; Boltaev, G. S.; Satlikov, N. Kh.; Tugushev, R. I.; Usmanov, T. [Institute of Electronics, Uzbekistan Academy of Sciences, Akademgorodok, 33, Dormon Yoli Street, Tashkent 100125 (Uzbekistan)

    2012-02-15

    Low-order harmonics, third and fifth, of IR (1064 nm) laser emission have been produced in laser ablation plasmas of the metals manganese, copper and silver. The harmonics were generated in a process triggered by laser ablation followed by frequency up-conversion of a fundamental laser beam that propagates parallel to the target surface. These studies were carried out in two temporal regimes by creating the ablation plasma using either nanosecond or picosecond pulses and then probing the plasma plume with pulses of the same duration. The spatiotemporal behavior of the generated harmonics was characterized and reveals the distinct composition and dynamics of the plasma species that act as nonlinear media, allowing the comparison of different processes that control the generation efficiency. These results serve to guide the choice of laser ablation plasmas to be used for efficient high harmonic generation of laser radiation.

  7. Experimental and computational study of complex shockwave dynamics in laser ablation plumes in argon atmosphere

    E-print Network

    Harilal, S. S.

    deposition (PLD),8 nanoparticle production,9 laser ion source (LIS),10 etc. In light source applications-spectrometry (LA-ICP-MS)5 to matrix-assisted laser desorption/ionization (MALDI),6 micromachining,7 pulsed laser. For short pulse laser ablation, with sp 1ps, the plasma formation takes place after deposition of the entire

  8. A low diffraction laser beam as applied to polymer ablation Xuanhui Lu,a)

    E-print Network

    Yao, Y. Lawrence

    of importance, especially in the growing microelectronic and precision medical device industry.4­6 The quality beam. The effects of the improved beam quality on a laser ablation process are investigated using2 laser, laser drilling I. INTRODUCTION Laser beam quality plays an important role in quality

  9. Proton extraction by laser ablation of transition metals

    NASA Astrophysics Data System (ADS)

    Velardi, L.; Delle Side, D.; Krása, J.; Nassisi, V.

    2014-07-01

    A study on the proton beams extraction from a plasma generated by pulsed laser ablation by targets containing transition metals is presented. The targets used were pure disks of titanium and tantalum and disks of TiH2, obtained by compression of TiH2 powder. The plasma was produced by means of a nanosecond excimer KrF laser operating at low irradiance (109-1010 W/cm2). The proton and ions emission was analyzed by the time-of-flight technique using a Faraday cup as ion collector. Studies on the produced protons and ions at different laser irradiances from 2 to 15 GW/cm2 were performed. The characterization showed that it is possible to obtain good proton fluxes from these targets, up to 1011 proton/pulse. The results obtained are very interesting if compared with those available in literature where proton fluxes per pulse ranging from 108 to 109 by hydride targets were obtained, at the same laser irradiances.

  10. Monitoring of tumor radio frequency ablation using derivative spectroscopy

    NASA Astrophysics Data System (ADS)

    Spliethoff, Jarich W.; Tanis, Erik; Evers, Daniel J.; Hendriks, Benno H. W.; Prevoo, Warner; Ruers, Theo J. M.

    2014-09-01

    Despite the widespread use of radio frequency (RF) ablation, an effective way to assess thermal tissue damage during and after the procedure is still lacking. We present a method for monitoring RF ablation efficacy based on thermally induced methemoglobin as a marker for full tissue ablation. Diffuse reflectance (DR) spectra were measured from human blood samples during gradual heating of the samples from 37 to 60, 70, and 85°C. Additionally, reflectance spectra were recorded real-time during RF ablation of human liver tissue ex vivo and in vivo. Specific spectral characteristics of methemoglobin were extracted from the spectral slopes using a custom optical ablation ratio. Thermal coagulation of blood caused significant changes in the spectral slopes, which is thought to be caused by the formation of methemoglobin. The time course of these changes was clearly dependent on the heating temperature. RF ablation of liver tissue essentially led to similar spectral alterations. In vivo DR measurements confirmed that the method could be used to assess the degree of thermal damage during RF ablation and long after the tissue cooled.

  11. Monitoring of tumor radio frequency ablation using derivative spectroscopy.

    PubMed

    Spliethoff, Jarich W; Tanis, Erik; Evers, Daniel J; Hendriks, Benno H W; Prevoo, Warner; Ruers, Theo J M

    2014-09-01

    Despite the widespread use of radio frequency (RF) ablation, an effective way to assess thermal tissue damage during and after the procedure is still lacking. We present a method for monitoring RF ablation efficacy based on thermally induced methemoglobin as a marker for full tissue ablation. Diffuse reflectance (DR) spectra were measured from human blood samples during gradual heating of the samples from 37 to 60, 70, and 85°C. Additionally, reflectance spectra were recorded real-time during RF ablation of human liver tissue ex vivo and in vivo. Specific spectral characteristics of methemoglobin were extracted from the spectral slopes using a custom optical ablation ratio. Thermal coagulation of blood caused significant changes in the spectral slopes, which is thought to be caused by the formation of methemoglobin. The time course of these changes was clearly dependent on the heating temperature. RF ablation of liver tissue essentially led to similar spectral alterations. In vivo DR measurements confirmed that the method could be used to assess the degree of thermal damage during RF ablation and long after the tissue cooled. PMID:25239499

  12. Laser ablation of graphite in different buffer gases

    SciTech Connect

    Puretzky, A.A. [Institute of Spectroscopy, Moscow (Russian Federation); Geohegan, D.B.; Haufler, R.E. [Oak Ridge National Lab., TN (United States)] [and others

    1996-04-01

    The KrF-laser ablation of graphite into 300 Torr of He, Ne, Ar, and Xe has been studied by fast imaging of the plasma emission and post-deposition analyses of collected film deposits. In each case, the soot which was redeposited on the irradiated rod following ablation was highly fullerene-deficient compared to the material collected on the sample disk 1.5 cm from the rod, as determined by laser desorption Fourier Transform Mass Spectrometry (FTMS) Investigation of the plasma plume propagation using fast ICCD photography reveals three main phases to the expansion: (1) forward motion, deceleration and stopping of the leading edge of the plume, (2) an apparent reflected shock within the plume which propagates backward and reflects from the rod surface, (3) coalescence of these two components, resulting in continued expansion and dissipation of the plasma and the appearance of glowing ultrafine particles. For the laser plume propagating in 300 Torr of Xe the characteristic time intervals for these three phases are 0-300 ns, 300-1000 ns, and 1-1000 {mu}s for phases (1), (2), and (3) respectively. The possible explanation of the observed difference in fullerene content is discussed on the basis of different plasma phases resulting in soot deposition on the rod and sample disk. The measurement of ro-vibrational spectra of electronically excited C{sub 2} has been performed. Rotational and vibrational temperatures, T{sub R} = 3000 {+-} 300K and T{sub V} = 6000 {+-} 500K have been obtained from the comparison of measured and calculated C{sub 2} -Swan band emission.

  13. Transport of ablated material through a water vapor atmosphere in pulsed laser deposition of hydroxylapatite

    NASA Astrophysics Data System (ADS)

    Arias, J. L.; Mayor, M. B.; Pou, J.; León, B.; Pérez-Amor, M.

    2002-01-01

    Hydroxylapatite (Ca 10(PO 4) 6(OH) 2) is a calcium phosphate used as a coating for dental and orthopaedical implants, because its composition and structure is similar to the mineral part of bone. As an alternative to the traditional plasma spray coating technique, pulsed laser deposition (PLD) has been applied. A hydroxylapatite target was ablated with an ArF laser in a water vapor pressure of 45 Pa to investigate the transport of the ablated material to the substrate. The substrate was placed at different distances from the target, inside and outside the plume. The distribution of coating thickness was measured by profilometry. The Ca/P ratio of the coatings was measured by EDAX, whereas their OH - and CO 32- content was evaluated by FT-IR spectroscopy. Inside the plume the thickness distributions correspond to an adiabatic expansion, while outside there is a diffusion of the species through the water vapor atmosphere to the substrate. The composition of the coatings also confirms this behavior.

  14. A comparison of nanosecond and femtosecond laser-induced plasma spectroscopy of brass samples

    Microsoft Academic Search

    V. Margetic; A Pakulev; A Stockhaus; M Bolshov; K Niemax; R Hergenröder

    2000-01-01

    The ablation of brass samples in argon shield gas by 170 fs and 6 ns laser pulses has been studied by optical emission spectroscopy of the evolving plasmas. Differences observed in the temporal behavior of the spectral line intensities are explained by the shielding effect of the Ar plasma for ns-pulses and the free expansion of the plasma of the

  15. UV-laser ablation of fused silica mediated by solid coating absorption

    NASA Astrophysics Data System (ADS)

    Ihlemann, J.

    2007-02-01

    Micro patterning of fused silica by laser ablation is very challenging due to the lack of absorption in the whole spectral range from the deep UV to the near IR. Beside vacuum UV lasers emitting at 157 nm or femtosecond lasers inducing multi photon absorption, indirect methods utilizing external absorbers are applied. Established methods like LIBWE and LIPAA are applicable in a backside configuration, i.e. the laser beam has to pass the workpiece before inducing ablation at the backside. This causes restrictions concerning the shape of the workpiece, i.e. generally a flat front surface is necessary. We propose an indirect ablation method that can be applied for both, back side and front side processing. The fused silica substrate to be machined is coated with a UV-absorbing oxide film. This film is irradiated using an excimer laser leading to ablation of the film and, at sufficiently high fluence, to surface ablation of the fused silica substrate. The ablation depth in the silica can be controlled by the fluence in excess to the threshold. The remaining coating in the unexposed areas is removed afterwards by large area irradiation of the whole surface at a fluence above the threshold of film ablation, but below the threshold of substrate ablation.

  16. Measurements of erbium laser-ablation efficiency in hard dental tissues under different water cooling conditions.

    PubMed

    Kuš?er, Lovro; Diaci, Janez

    2013-10-01

    Laser triangulation measurements of Er:YAG and Er,Cr:YSGG laser-ablated volumes in hard dental tissues are made, in order to verify the possible existence of a "hydrokinetic" effect that has been proposed as an alternative to the "subsurface water expansion" mechanism for hard-tissue laser ablation. No evidence of the hydrokinetic effect could be observed under a broad range of tested laser parameters and water cooling conditions. On the contrary, the application of water spray during laser exposure of hard dental material is observed to diminish the laser-ablation efficiency (AE) in comparison with laser exposure under the absence of water spray. Our findings are in agreement with the generally accepted principle of action for erbium laser ablation, which is based on fast subsurface expansion of laser-heated water trapped within the interstitial structure of hard dental tissues. Our measurements also show that the well-known phenomenon of ablation stalling, during a series of consecutive laser pulses, can primarily be attributed to the blocking of laser light by the loosely bound and recondensed desiccated minerals that collect on the tooth surface during and following laser ablation. In addition to the prevention of tooth bulk temperature buildup, a positive function of the water spray that is typically used with erbium dental lasers is to rehydrate these minerals, and thus sustaining the subsurface expansion ablation process. A negative side effect of using a continuous water spray is that the AE gets reduced due to the laser light being partially absorbed in the water-spray particles above the tooth and in the collected water pool on the tooth surface. Finally, no evidence of the influence of the water absorption shift on the hypothesized increase in the AE of the Er,Cr:YSGG wavelength is observed. PMID:24105399

  17. An advanced optical system for laser ablation propulsion in space

    NASA Astrophysics Data System (ADS)

    Bergstue, Grant; Fork, Richard; Reardon, Patrick

    2014-03-01

    We propose a novel space-based ablation driven propulsion engine concept utilizing transmitted energy in the form of a series of ultra-short optical pulses. Key differences are generating the pulses at the transmitting spacecraft and the safe delivery of that energy to the receiving spacecraft for propulsion. By expanding the beam diameter during transmission in space, the energy can propagate at relatively low intensity and then be refocused and redistributed to create an array of ablation sites at the receiver. The ablation array strategy allows greater control over flight dynamics and eases thermal management. Research efforts for this transmission and reception of ultra-short optical pulses include: (1) optical system design; (2) electrical system requirements; (3) thermal management; (4) structured energy transmission safety. Research has also been focused on developing an optical switch concept for the multiplexing of the ultra-short pulses. This optical switch strategy implements multiple reflectors polished into a rotating momentum wheel device to combine the pulses from different laser sources. The optical system design must minimize the thermal load on any one optical element. Initial specifications and modeling for the optical system are being produced using geometrical ray-tracing software to give a better understanding of the optical requirements. In regards to safety, we have advanced the retro-reflective beam locking strategy to include look-ahead capabilities for long propagation distances. Additional applications and missions utilizing multiplexed pulse transmission are also presented. Because the research is in early development, it provides an opportunity for new and valuable advances in the area of transmitted energy for propulsion as well as encourages joint international efforts. Researchers from different countries can cooperate in order to find constructive and safe uses of ordered pulse transmission for propulsion in future space-based missions.

  18. Iron isotope composition of particles produced by UV-femtosecond laser ablation of natural oxides, sulfides, and carbonates.

    PubMed

    d'Abzac, Francois-Xavier; Beard, Brian L; Czaja, Andrew D; Konishi, Hiromi; Schauer, James J; Johnson, Clark M

    2013-12-17

    The need for femtosecond laser ablation (fs-LA) systems coupled to MC-ICP-MS to accurately perform in situ stable isotope analyses remains an open question, because of the lack of knowledge concerning ablation-related isotopic fractionation in this regime. We report the first iron isotope analysis of size-resolved, laser-induced particles of natural magnetite, siderite, pyrrhotite, and pyrite, collected through cascade impaction, followed by analysis by solution nebulization MC-ICP-MS, as well as imaging using electron microscopy. Iron mass distributions are independent of mineralogy, and particle morphology includes both spheres and agglomerates for all ablated phases. X-ray spectroscopy shows elemental fractionation in siderite (C-rich agglomerates) and pyrrhotite/pyrite (S-rich spheres). We find an increase in (56)Fe/(54)Fe ratios of +2‰, +1.2‰, and +0.8‰ with increasing particle size for magnetite, siderite, and pyrrhotite, respectively. Fe isotope differences in size-sorted aerosols from pyrite ablation are not analytically resolvable. Experimental data are discussed using models of particles generation by Hergenröder and elemental/isotopic fractionation by Richter. We interpret the isotopic fractionation to be related to the iron condensation time scale, dependent on its saturation in the gas phase, as a function of mineral composition. Despite the isotopic variations across aerosol size fractions, total aerosol composition, as calculated from mass balance, confirms that fs-LA produces a stoichiometric sampling in terms of isotopic composition. Specifically, both elemental and isotopic fractionation are produced by particle generation processes and not by femtosecond laser-matter interactions. These results provide critical insights into the analytical requirements for laser-ablation-based stable isotope measurements of high-precision and accuracy in geological samples, including the importance of quantitative aerosol transport to the ICP. PMID:24261311

  19. Outcome of Endovenous Laser Ablation of Varicose Veins

    PubMed Central

    Rustempasic, Nedzad; Cvorak, Alemko; Agincic, Alija

    2014-01-01

    ABSTRACT Introduction: In Bosnia and Herzegovina according to available data, treatment of incompetent superficial lower extremity varicose veins by endovenous laser ablation (EVLA) has been introduced two years ago and so far no paper has been published regarding results of EVLA treatment of patients from our country. We wanted to present our results with EVLA treatment. Aim of study: to evaluate and compare primary posttreatment outcomes of endovenous laser ablation (EVLA) with classical surgical method of varicose vein treatment. Patients and methods: The study was clinical and prospective. It was carried out at Clinic for vascular surgery in Sarajevo where fifty-eight (58) patients received surgical treatment for varicose veins and in Aesthetic Surgery Center “Nasa mala klinika” in Sarajevo were sixty-one (61) patients with varicose veins were treated by endovenous laser ablation. Total 119 patients (limbs) with pathologic reflux only in great saphenous vein were evaluated between 1st of January 2013 and 31st of April 2014. Following primary outcome endpoints were evaluated smean day of return to normal everyday activities, patient subjective quantification of pain during first seven days after intervention, incidence of deep venous thrombosis (DVT), incidence of wound bleeding requiring surgical intervention, incidence of peri-saphenous vein hematoma and infection rate. Results: Mean of return to normal activities (expressed in days after intervention); EVLA vs. stripping (surgery) =1.21vs12.24, T test 13,619; p=0, 000, p<0,05. T test was used for comparing Mean value of visual pain analog scale for the first 7 days between groups, for all seven days pain was significantly higher in surgical group of patients as compared to EVLA group; p<0,05. Incidence of hematoma greater than 1% of total body surface area was significantly higher in patients receiving surgical treatment; Pearson Chi Square=23,830, p<0,05; odds ratio:10,453. Incidences of infection, deep venous thrombosis and posttreatment bleeding were not statistically different between analyzed groups; EVLA vs Surgery (Pearson Chi Square =3,237; p>0,05; Pearson Chi Square=2,139, p>0,05, Pearson Chi Square=2,139, p>0,05, respectively.) Conclusion: EVLA offers better patient recovery in terms of significantly lower post treatment pain, faster return to everyday activities and lower incidence of bruising (hematomas). PMID:25568583

  20. Ablation driven by hot electrons generated during the ignitor laser pulse in shock ignition

    SciTech Connect

    Piriz, A. R.; Rodriguez Prieto, G. [E.T.S.I. Industriales, Universidad de Castilla-La Mancha and Instituto de Investigaciones Energeticas, 13071 Ciudad Real (Spain); Tahir, N. A. [GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt (Germany); Zhang, Y. [School of Physics and Optoelectronic Technology, Dalian University of Technology, 116024 Dalian (China); Liu, S. D.; Zhao, Y. T. [Institute of Modern Physics, Chinese Academy of Science, 730000 Lanzhou (China)

    2012-12-15

    An analytical model for the ablation driven by hot electrons is presented. The hot electrons are assumed to be generated during the high intensity laser spike used to produce the ignitor shock wave in the shock ignition driven inertial fusion concept, and to carry on the absorbed laser energy in its totality. Efficient energy coupling requires to keep the critical surface sufficiently close to the ablation front and this goal can be achieved for high laser intensities provided that the laser wavelength is short enough. Scaling laws for the ablation pressure and the other relevant magnitudes of the ablation cloud are found in terms of the laser and target parameters. The effect of the preformed plasma assembled by the compression pulse, previous to the ignitor, is also discussed. It is found that a minimum ratio between the compression and the ignitor pulses would be necessary for the adequate matching of the corresponding scale lengths.

  1. Plasma mediated ablation of biological tissues with nanosecond-to-femtosecond laser pulses: relative role of linear and nonlinear absorption

    Microsoft Academic Search

    Alexander A. Oraevsky; Luiz B. Da Silva; Alexander M. Rubenchik; Michael D. Feit; M. E. Glinsky; Michael D. Perry; Beth M. Mammini; B. C. Stuart

    1996-01-01

    Plasma mediated ablation of collagen gels and porcine cornea was studied at various laser pulse durations in the range of 1 ns-300 fs at 1053-nm wavelength. It was found that pulsed laser ablation of transparent and weakly absorbing gels is always mediated by plasma. On the other hand, ablation of strongly absorbing tissues is mediated by plasma in the ultrashort-pulse

  2. Laser hydrothermal reductive ablation of titanium monoxide: Hydrated TiO particles with modified Ti/O surface

    SciTech Connect

    Blazevska-Gilev, Jadranka [Laboratory of Laser Chemistry, Institute of Chemical Process Fundamentals, ASCR, Prague 16502 (Czech Republic); University St.Cyril and Methodious, Skopje 1000, Former Yugoslav Republic of Macedonia (Macedonia, The Former Yugoslav Republic of); Jandova, Vera [Laboratory of Laser Chemistry, Institute of Chemical Process Fundamentals, ASCR, Prague 16502 (Czech Republic); Kupcik, Jaroslav [Laboratory of Laser Chemistry, Institute of Chemical Process Fundamentals, ASCR, Prague 16502 (Czech Republic); Institute of Inorganic Chemistry, ASCR, Rez 25068 (Czech Republic); Bastl, Zdenek [J. Heyrovsky Institute of Physical Chemistry, ASCR, Prague 18223 (Czech Republic); Subrt, Jan; Bezdicka, Petr [Institute of Inorganic Chemistry, ASCR, Rez 25068 (Czech Republic); Pola, Josef, E-mail: pola@icpf.cas.cz [Laboratory of Laser Chemistry, Institute of Chemical Process Fundamentals, ASCR, Prague 16502 (Czech Republic)

    2013-01-15

    IR laser- and UV laser-induced ablation of titanium monoxide (TM) in hydrogen (50 Torr) is compared to the same process induced in vacuum and shown to result in deposition of hydrated surface modified nanostructured titanium suboxide films. Complementary analyses of the films deposited in vacuum and in hydrogen by Fourier transform infrared, Raman and X-ray photoelectron spectroscopy, X-ray diffraction and electron microscopy allowed to determine different features of both films and propose a mechanism of surface modification of ejected particles, which involves hydrothermal reduction of TM and subsequent reactions of evolved water. The films exert good adhesion to metal and quartz surfaces and are hydrophobic in spite of having their surface coated with adsorbed water. - Graphical abstract: Laser ablation of titanium monoxide (TiO) in hydrogen involves a sequence of H{sub 2} and H{sub 2}O eliminations and additions and yields hydrated amorphous nanostructured titanium suboxide which is richer in oxygen than TiO. Highlights: Black-Right-Pointing-Pointer IR and UV laser ablated particles of titanium monoxide (TiO) undergo amorphization. Black-Right-Pointing-Pointer Films deposited in vacuum have TiO stoichiometry and are oxidized in atmosphere. Black-Right-Pointing-Pointer Films deposited in hydrogen are hydrated and have more O in topmost layers. Black-Right-Pointing-Pointer Films modification in hydrogen is explained by reactions in hydrogen plasma.

  3. Ablation of transition metal oxides by different laser pulse duration and thin films deposition

    Microsoft Academic Search

    A. Giardini Guidoni; C Flamini; F Varsano; M Ricci; R Teghil; V Marotta; T. M Di Palma

    2000-01-01

    Thin films of transition metal oxides are of interest in many applications such as anticorrosion coatings and optical and electrochromic devices. In this work, the effect of different wavelength and pulse duration on ablation of oxides target has been investigated. The plume has been characterized by mass spectrometry and optical spectroscopy. Ablation thresholds have been measured by detecting ion emission

  4. The effect of free-electron laser pulse structure on mid-infrared soft-tissue ablation: ablation metrics.

    PubMed

    Mackanos, Mark A; Kozub, John A; Jansen, E Duco

    2005-04-21

    Pulsed mid-infrared (6.45 microm) radiation has been shown to cut soft tissue with minimal collateral damage (<40 microm); however, the mechanism of ablation has not been elucidated to date. The goal of this research was to examine the role of the unique pulse structure of the Vanderbilt Mark-III free-electron laser (FEL) and its role in the efficient ablation of soft tissue with minimal collateral damage. The effect of the picosecond micropulse was examined by running the native FEL pulse structure through a pulse stretcher in order to increase the micropulse length from 1 ps up to approximately 200 ps. This allowed us to determine whether or not the picosecond train of micropulses played any role in the ablation process. The ablation threshold was determined for water and mouse dermis for each micropulse length. While the results of the analysis showed a statistically significant difference between 1 and 200 ps, the average per cent difference amounts to only 28% and is not proportional to the 200-fold drop in peak irradiance. The ablation efficiency was also measured on gelatin and mouse dermis for the different micropulse lengths. A small but statistically significant difference was observed between 1 and 200 ps, with the 200 ps pulse being more efficient on gelatin, and with the opposite trend for mouse dermis. We have shown that there is a small effect of micropulse duration of the FEL on the ablation process; however, this effect is negligible between 1 and 200 ps given that there is a 200-fold decrease in peak intensity. These results suggest that as we move forward in developing alternative laser sources for tissue ablation to replace the FEL, the picosecond micropulse structure is not a critical parameter that needs to be duplicated. PMID:15815101

  5. The effect of free-electron laser pulse structure on mid-infrared soft-tissue ablation: ablation metrics

    NASA Astrophysics Data System (ADS)

    Mackanos, Mark A.; Kozub, John A.; Jansen, E. Duco

    2005-04-01

    Pulsed mid-infrared (6.45 µm) radiation has been shown to cut soft tissue with minimal collateral damage (<40 µm) however, the mechanism of ablation has not been elucidated to date. The goal of this research was to examine the role of the unique pulse structure of the Vanderbilt Mark-III free-electron laser (FEL) and its role in the efficient ablation of soft tissue with minimal collateral damage. The effect of the picosecond micropulse was examined by running the native FEL pulse structure through a pulse stretcher in order to increase the micropulse length from 1 ps up to ~200 ps. This allowed us to determine whether or not the picosecond train of micropulses played any role in the ablation process. The ablation threshold was determined for water and mouse dermis for each micropulse length. While the results of the analysis showed a statistically significant difference between 1 and 200 ps, the average per cent difference amounts to only 28% and is not proportional to the 200-fold drop in peak irradiance. The ablation efficiency was also measured on gelatin and mouse dermis for the different micropulse lengths. A small but statistically significant difference was observed between 1 and 200 ps, with the 200 ps pulse being more efficient on gelatin, and with the opposite trend for mouse dermis. We have shown that there is a small effect of micropulse duration of the FEL on the ablation process; however, this effect is negligible between 1 and 200 ps given that there is a 200-fold decrease in peak intensity. These results suggest that as we move forward in developing alternative laser sources for tissue ablation to replace the FEL, the picosecond micropulse structure is not a critical parameter that needs to be duplicated.

  6. Laser ablation and selective excitation directed to trace element analysis

    NASA Astrophysics Data System (ADS)

    Kwong, V. H. S.

    1980-08-01

    A trace (element) analyser based on laser ablation and selectively excited radiation is proposed as an ultramicro-ultratrace technique for quantitative element analysis. Measurements of trace quantities of chromium in samples of NBS standard reference material (steel), doped skim milk powder and doped flour were undertaken. There is a linear 45 deg slope for Log/Log plot dependence of signal versus concentration that extends at least up to 1.3% (concentration by weight) in the case of chromium. The detection limit for the current unoptimized system is in the ppm range which corresponds to the absolute detection limit of 10 to the 13th power g. Although no chemical interference effects were observed, two physical interference effects were evident: differential mass vaporization and inhomogeneous spatial and temporal distribution of fast expanding analyte. The differential Doppler shift between the atoms along the line of observation reduces self-absorption even at high analyte concentrations.

  7. Synthesis of magnetic nanoparticles by pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Franzel, L.; Bertino, M. F.; Huba, Z. J.; Carpenter, E. E.

    2012-11-01

    Magnetic nanoparticles were prepared by laser ablation of Fe foil in ethanol. The nanoparticles consisted of Fe3O4 and Fe3C and were superparamagnetic with a saturation magnetization Ms = 124 emu/g. Zero field cooled (ZFC) measurements collected at an applied field of 50 Oe displayed a maximum magnetic susceptibility at 120 K with a broad distribution. Field cooled (FC) measurements collected during cooling and heating showed a thermal hysteresis indicative of temperature dependent magnetic viscosity. The magnetic viscosity was calculated from thermoremanent magnetization (TRM) plots and it increased with decreasing temperature. The activation volume of these non uniform magnetic states was calculated from TRM measurements and it was found to decrease with decreasing temperature. The decrease in activation diameters was interpreted as a decrease in exchange length, and hence a decrease in particle-particle interactions.

  8. Optical ablation by high-power short-pulse lasers

    NASA Astrophysics Data System (ADS)

    Stuart, B. C.; Feit, Michael D.; Herman, S.; Rubenchik, A. M.; Shore, B. W.; Perry, M. D.

    1996-02-01

    Laser-induced damage threshold measurements were performed on homogeneous and multilayer dielectrics and gold-coated optics at 1053 and 526 nm for pulse durations tau ranging from 140 fs to 1 ns. Gold coatings were found, both experimentally and theoretically, to be limited to 0.6 J/cm2 in the subpicosecond range for 1053-nm pulses. In dielectrics, we find qualitative differences in the morphology of damage and a departure from the diffusion-dominated tau 1/ 2 scaling that indicate that damage results from plasma formation and ablation for tau <=10 ps and from conventional heating and melting for tau >50 ps. A theoretical model based on electron production by multiphoton ionization, joule heating, and collisional (avalanche) ionization is in quantitative agreement with both the pulse-width and the wavelength scaling of experimental results.

  9. Analysis of soft tissue ablation using the pulse stretched free electron laser

    Microsoft Academic Search

    Mark A. Mackanos; John A. Kozub; Darrel L. Ellis; E. Duco Jansen

    2005-01-01

    The Mark-III Free Electron Laser (FEL), tuned to 6.45 microns in wavelength has been demonstrated to provide for efficient ablation in ocular, neural, and dermal tissues with minimal collateral damage. To date, the role of the unique pulse structure of the FEL on the ablation mechanism has not been determined. In this study, the native pulse structure of the FEL,

  10. Modeling CO{sub 2} laser ablation impulse of polymers in vapor and plasma regimes

    SciTech Connect

    Sinko, John E. [Micro-Nano Global Center of Excellence, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Phipps, Claude R. [Photonic Associates LLC, 200A Ojo de la Vaca Road, Santa Fe, New Mexico 87508 (United States)

    2009-09-28

    An improved model for CO{sub 2} laser ablation impulse in polyoxymethylene and similar polymers is presented that describes the transition effects from the onset of vaporization to the plasma regime in a continuous fashion. Several predictions are made for ablation behavior.

  11. Integration of multimode waveguides and micromirror couplers in printed circuit boards using laser ablation

    Microsoft Academic Search

    G. Van Steenberge; P. Geerinck; S. Van Put; P. Van Daele

    2003-01-01

    Integration of optical interconnections on a Printed Circuit Board (PCB) is very challenging, as it should remain compatible with existing PCB manufacturing technology. We will describe the use of laser ablation, already used in PCB manufacturing for microvia's, as a suitable technique for the fabrication of multimode waveguides and micromirrors to provide optical coupling. The focus is on ablation of

  12. A comparative study of single and double pulse of laser induced breakdown spectroscopy of silver

    SciTech Connect

    Rashid, Babar; Ahmed, Rizwan; Ali, Raheel; Baig, M. A. [Atomic and Molecular Physics Laboratory, Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan)

    2011-07-15

    We present a comparative study of the collinear and orthogonal pre-ablation dual pulse configurations of laser induced breakdown spectroscopy (LIBS) of silver using Nd:YAG lasers. The effect of the inter-pulse delay and the ratio of the laser pulse energies on the signal intensity enhancement for both the dual pulse configurations have been investigated. Using the first laser at 532 nm and second laser at 1064 nm delayed by 5 {mu}s, we achieved nearly 2 times signal enhancement in the collinear double-pulsed configuration and nearly 12 times in the pre-ablation orthogonal configuration as compared to SP LIBS. It is ascertained that at the optimized value of the inter-pulse delay between the two lasers, the intensity ratio of the neutral silver lines follows the local thermo dynamical equilibrium (LTE) condition and it is also in excellent agreement with that of the relative transitions probabilities ratio listed in the NIST data base.

  13. The application of laser ablation-inductively coupled plasma-mass spectrometry to in situ U–Pb zircon geochronology

    Microsoft Academic Search

    Simon E. Jackson; Norman J. Pearson; William L. Griffin; Elena A. Belousova

    2004-01-01

    This paper reports new developments in in situ U–Pb zircon geochronology using 266 and 213 nm laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS).Standard spot ablation (spot diameters 40–80 ?m) was employed, with no sampling strategies employed specifically to minimise elemental fractionation. Instead, He ablation gas and carefully replicated ablation conditions were employed to maintain constant ablation-related elemental fractionation of Pb and

  14. Experimental investigation on thermal ablation of carbon-fiber/epoxy composite irradiated by continuous wave laser

    NASA Astrophysics Data System (ADS)

    He, Minbo; Ma, Zhiliang; Chen, Linzhu; Lin, Xinwei; Zhou, Menglian

    2015-05-01

    The tests of carbon-fiber/epoxy composite laminates, subjected to a tangential gas-flow and 1070 nm continuous wave laser are carried out to acquire the ablation laws of samples on the conditions of different gas-flow. Simultaneously, considered the images from camera of large dynamic range, the damage laws of samples are also obtained for various laser power densities. Experimental results reveal that, without airflow on sample surface, the smoke caused by laser heating can be quickly on fire which causes a burn damage on the surface of samples so that the mass loss is most of all. However, the tangential airflow can remove away the smoke which has a weakening effect on the energy of incidence laser. So the ablation depth has an obvious increase in laser irradiation area. Unlike airflow, nitrogen flow can obviously restrain oxidation ablation on surface so that the ablation damage in laser irradiation area is relatively not severe. On the other hand, as laser power density increases, the mass loss of samples continues to rise but isn't proportional. And the ablation heat with the increase of power density shows a complex change. Below power density of 390 W/cm2, the mass loss mainly depends on the pyrolysis of epoxy while the ablation heat has a gradual decrease. Along with power density increasing but less than 1330 W/cm2 , the oxidation ablation of carbon fibers will be a leading factor and the ablation heat shows a little increase. Above power density of 1330 W/cm2 , the carbon fibers turn up the phenomenon of sublimation. What's more, airflow removed effects will be enhanced in high temperature. In this case, the ablation heat again has a trend of decrease.

  15. Custom specific fabrication of integrated optical devices by excimer laser ablation of polymers

    NASA Astrophysics Data System (ADS)

    Klotzbuecher, Thomas; Popp, Martin; Braune, Torsten; Haase, Jens; Gaudron, Anne; Smaglinski, Ingo; Paatzsch, Thomas; Bauer, Hans-Dieter; Ehrfeld, Wolfgang

    2000-06-01

    Excimer laser ablation was used for direct writing of multimode waveguide structures with passive fiber alignment grooves in polymers. First, integrated optical multimode components were simulated by the method of beam propagation to optimize the optical performance of the design. Then the CNC codes for laser machining were created directly from the corresponding CAD data. ArF Excimer laser radiation of wavelength (lambda) equals 193 nm was used for ablation of adjacent grooves with a cross sectional area of 50 X 50 micrometers 2 and lengths in the order of several mm. The laser-written grooves were filled with a liquid pre-polymer which after UV-curing served as the waveguiding structures. The smoothest surfaces during laser ablation were achieved by applying several ablation scans with reduced material removal rates but higher feedrates. Debris formation, also influencing the surface roughness, was suppressed or minimized by making use of capable polymers. With the method of laser ablation linear waveguides of length 1 equals 10 mm with insertion losses Li in the rang of 1.3 to 1.9 dB have been realized for (lambda) equals 1310 nm, depending on the polymer used. By means of 1 X 2-splitters, 4 X 4 as well as 4 X 16 starcouplers it was shown that laser ablation is a well suited tool for rapid prototyping of integrated optical multimode elements.

  16. Effect of Pulsed Laser Ablation and Continuous Laser Heating on the Adhesion and Cohesion of Cold Sprayed Ti-6Al-4V Coatings

    NASA Astrophysics Data System (ADS)

    Perton, M.; Costil, S.; Wong, W.; Poirier, D.; Irissou, E.; Legoux, J.-G.; Blouin, A.; Yue, S.

    2012-12-01

    The individual and cumulative effects of in situ pulsed laser ablation and continuous laser pre-heating on adhesion and cohesion strength of cold sprayed Ti-6Al-4V coatings are investigated. Laser beams were coupled to a cold spray gun in order to ablate and pre-heat the substrate surface a few milliseconds prior to the impact of the spray particles. Cohesion and adhesion strength were evaluated by scratch test, standard ASTM C633 pull test and laser shock (LASAT) technique. The effects of laser ablation before and during cold spray operations were investigated. Results demonstrate that laser ablation of the substrate before cold spraying led to a smooth surface which improved adhesion strength. However, when laser ablation was maintained throughout the cold spray process, i.e., in between the coating layers, a reduction of cohesion and adhesion was observed. These negative effects were circumvented when laser ablation and laser pre-heating were combined.

  17. Bioavailable nanoparticles obtained in laser ablation of a selenium target in water

    NASA Astrophysics Data System (ADS)

    Kuzmin, P. G.; Shafeev, Georgii A.; Voronov, Valerii V.; Raspopov, R. V.; Arianova, E. A.; Trushina, E. N.; Gmoshinskii, I. V.; Khotimchenko, S. A.

    2012-11-01

    The process of producing colloidal solutions of selenium nanoparticles in water using the laser ablation method is described. The prospects of using nanoparticles of elementary selenium as a nutrition source of this microelement are discussed.

  18. Preliminary results of human scleral ablation in vitro with Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Pergadia, Vani R.; Vari, Sandor G.; Fishbein, Michael C.; Shi, Wei-Qiang; Grundfest, Warren S.

    1994-02-01

    This study evaluated the effect of the Ho:YAG laser operating at a wavelength of 2.1 micrometers and a repetition rate of 2 Hz on a human scleral tissue. The effects were assessed in terms of the ablation rate (micrometers /pulse) and the thermal damage (micrometers ) induced. The results were compared to those found from porcine scleral ablation. Data indicate that for the pulsed Ho:YAG laser, the ablation rate of scleral tissue increases linearly with laser fluence. The ablation rates are about 40% lower for the human scleral tissue than for the porcine scleral tissue at the same fluences. Data indicate that the mean Ho:YAG laser induced thermal damage is not significantly affected by varying the fluence.

  19. Bioavailable nanoparticles obtained in laser ablation of a selenium target in water

    SciTech Connect

    Kuzmin, P G; Shafeev, Georgii A; Voronov, Valerii V; Raspopov, R V; Arianova, E A; Trushina, E N; Gmoshinskii, I V; Khotimchenko, S A

    2012-11-30

    The process of producing colloidal solutions of selenium nanoparticles in water using the laser ablation method is described. The prospects of using nanoparticles of elementary selenium as a nutrition source of this microelement are discussed. (nanoparticles)

  20. Laser-induced breakdown spectroscopy of tantalum plasma

    NASA Astrophysics Data System (ADS)

    Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan-ul-Haq

    2013-07-01

    Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (? ˜ 1064 nm, ? ˜ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO2: N2: He), O2, N2, and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis.

  1. Infrared nanosecond laser-metal ablation in atmosphere: Initial plasma during laser pulse and further expansion

    SciTech Connect

    Wu, Jian; Wei, Wenfu; Li, Xingwen; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi 710049 (China)] [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi 710049 (China)

    2013-04-22

    We have investigated the dynamics of the nanosecond laser ablated plasma within and after the laser pulse irradiation using fast photography. A 1064 nm, 15 ns laser beam was focused onto a target made from various materials with an energy density in the order of J/mm{sup 2} in atmosphere. The plasma dynamics during the nanosecond laser pulse were observed, which could be divided into three stages: fast expansion, division into the primary plasma and the front plasma, and stagnation. After the laser terminated, a critical moment when the primary plasma expansion transited from the shock model to the drag model was resolved, and this phenomenon could be understood in terms of interactions between the primary and the front plasmas.

  2. Manufacturing of Medical Implants by Combination of Selective Laser Melting and Laser Ablation

    NASA Astrophysics Data System (ADS)

    Hallmann, S.; Glockner, P.; Daniel, C.; Seyda, V.; Emmelmann, C.

    2015-04-01

    The perfect fit of hip stem prostheses is supposed to have positive effects on their lifetime performance. Moreover, the ingrowth of tissue into the surface of the implant has to be assured to create a firm and load bearing contact. For the manufacturing of customized hip stem prostheses, the technology of Selective Laser Melting has shown promising results. Poor surface quality, however, makes it necessary to finish up the part by e.g., sand blasting or polishing. With the use of laser ablation for post-processing, reproducible and functionalized surface morphologies might be achievable. Hence, with the motive to produce customized hip stem prostheses, a combined process chain for both mentioned laser technologies is developed. It is examined what type of surface should be produced at which part of the process chain. The produced implants should contain the demanded final surface characteristics without any conventional post-processing. Slight advantages for the Selective Laser Melting regarding the accuracy for different geometrical structures of 400 ?m depth were observed. However, an overall improvement of surface quality after the laser ablation process in terms of osseointegration could be achieved. A complete laser based production of customized hip stem implants is found to be with good prospects.

  3. Analysis of two colliding laser-produced plasmas by emission spectroscopy and fast photography

    Microsoft Academic Search

    C. Sánchez-Aké; D. Mustri-Trejo; T. García-Fernández; M. Villagrán-Muniz

    2010-01-01

    In this work two colliding laser-induced plasmas (LIP) on Cu and C were studied by means of time resolved emission spectroscopy and fast photography. The experiments were performed using two opposing parallel targets of Cu and C in vacuum, ablated with two synchronized ns lasers. The results showed an increased emission intensity from copper ions Cu II (368.65, 490.97, 493.16,

  4. Laser ablation of bicomponent systems: A probe of molecular ejection Yaroslava G. Yingling,a)

    E-print Network

    in mass spectrometry matrix assisted laser desorption ionization MALDI ,1 thin polymer film deposition matrix assisted pulsed laser evaporation ,2 and dry image production laser ablation transfer .3 Although to toluene is important. Using electron impact ion- ization, the amount of each neutral component

  5. Optoacoustic effects during Er:YAG laser ablation in hard dental tissue

    Microsoft Academic Search

    Matjaz Lukac; Ladislav Grad; Janez Mozina; Dusan Sustercic; Nenad Funduk; Uros Skaleric

    1994-01-01

    Optoacoustic method is a very useful tool for studying laser induced processes in hard dental tissues. In principle, the method can also be used for on-line monitoring of laser drilling. Our study, however, shows that at high laser energies the optoacoustic energy is not proportional to the volume of the ablated hard dental tissue. In addition, the optoacoustic signal depends

  6. Inertial Confinement Fusion Ablator Physics Experiments at the Omega Laser Facility

    Microsoft Academic Search

    Rick Olson; Gordon Chandler; Ray Leeper

    2000-01-01

    In collaboration with Los Alamos National Laboratory, Lawrence Livermore National Laboratory, and the University of Rochester Laboratory for Laser Energetics, we have performed planar shock and burnthrough experiments with polyimide and beryllium ablator samples. The experiments utilize 15 beams of the Omega Laser to heat halfraums (i.e., cylindrical hohlraums with one laser entrance hole) to radiation temperatures of 160 eV.

  7. KrF laser-induced ablation and patterning of Y--Ba--Cu--O films

    SciTech Connect

    Heitz, J.; Wang, X.Z.; Schwab, P.; Baeuerle, D. (Angewandte Physik, Johannes-Kepler-Universitaet Linz, A-4040 Linz (Austria)); Schultz, L. (Siemens AG, Research Laboratories, D-8520 Erlangen (Germany))

    1990-09-01

    The ablation and patterning of Y--Ba--Cu--O films on (100) SrTiO{sub 3} and (100) MgO substrates by KrF excimer-laser light projection was investigated. Three different regimes of laser-material interactions were observed. Transition temperatures and critical current densities in laser-fabricated strip lines were investigated.

  8. Femtosecond laser ablation with single and two-photon excitation for MEMS

    Microsoft Academic Search

    Mohamed Abdelfattah Kottb Ahmad Elbandrawy

    2006-01-01

    There is an increasing interest in femtosecond laser micromachining of materials because of the femtosecond laser's unique high peak power, ultrashort pulse width, negligible heat conductivity process during the laser pulse, and the minimal heat affected zone, which is in the same order of magnitude of the ablated submicron spot. There are some obstacles in reaching optimal and reliable micromachining

  9. Theoretical photo-thermo-hydrodynamic approach to the laser ablation of metals

    NASA Astrophysics Data System (ADS)

    Stafe, Mihai

    2012-12-01

    Here, we employ theory and experiments to investigate the laser ablation process of a metal (Al) using nanosecond laser-pulses at 532 nm wavelength in atmospheric air. We analyze experimentally the dependence of the ablation rate of Al on laser fluence which is varied over a wide range (from ˜4 to 500 J/cm2) by changing the laser pulses energy. The experimental data indicate that the ablation rate increases approximately linearly to ˜1.5 ?m/pulse when increasing the fluence to ˜50 J/cm2, whereas further increase of the laser fluence leads to a much slower, non-linear increase of the ablation rate. By extrapolating towards zero the linear fitting curve, we find the ablation threshold fluence of Al to be ˜1.9 J/cm2. To understand and control the underlying phenomena involved in laser ablation, we propose a robust and efficient theoretical model for reliable yet fast calculation of the ablation rate of metals. We use a one-dimensional photo-thermo-hydrodynamic model that accounts for the material heating, melting, evaporation, melt ejection, and ablation plasma shielding during nanosecond laser irradiation. The model considers that the reflectivity of the target surface, the heat capacity, thermal conductivity, and the mass density of the metallic material depend on the aggregation state. The non-linear heat equation of the model is solved numerically in a multi-step iterative method. The solution of the heat equation gives the time evolution of the temperature within the target, leading further to the evaporation and melt ejection velocities, and to the ablation rate. There is a good agreement between the numerical and the experimental results on the ablation rate for a very wide fluence range, i.e., up to 150 J/cm2 when phase separation occurs in the ablating layer whose average temperature during the laser pulse reaches the Al critical temperature. The validity fluence range of the present model is approximately one order of magnitude wider than in previous theoretical works on nanosecond laser ablation of metals.

  10. Investigations on laser ablation–microwave induced plasma–atomic emission spectrometry using polymer samples

    Microsoft Academic Search

    F. Leis; H. E. Bauer; L. Prodan; K. Niemax

    2001-01-01

    The potential of laser ablation–microwave induced plasma–atomic emission spectrometry (LA–MIP–AES) for the analysis of plastic materials has been investigated. A Nd\\/YAG laser, operated in its fundamental mode at 1064 nm, was used to ablate small amounts of various plastics. The sample atoms were transported and excited in a closely neighbored continuously running microwave induced plasma (MIP) operated in argon or

  11. Human cornea wound healing in organ culture after Er:YAG laser ablation

    NASA Astrophysics Data System (ADS)

    Shen, Jin-Hui; Joos, Karen M.; Robinson, Richard D.; Shetlar, Debra J.; O'Day, Denis M.

    1998-06-01

    Purpose: To study the healing process in cultured human corneas after Er:YAG laser ablation. Methods: Human cadaver corneas within 24 hours post mortem were ablated with a Q- switched Er:YAG laser at 2.94 micrometer wavelength. The radiant exposure was 500 mJ/cm2. The cornea was cultured on a tissue supporting frame immediately after the ablation. Culture media consisted of 92% minimum essential media, 8% fetal bovine serum, 0.125% HEPES buffer solution, 0.125% gentamicin, and 0.05% fungizone. The entire tissue frame and media container were kept in an incubator at 37 degrees Celsius and 5% CO2. Serial macroscopic photographs of the cultured corneas were taken during the healing process. Histology was performed after 30 days of culture. Results: A clear ablated crater into the stroma was observed immediately after the ablation. The thickness of thermal damage ranges between 1 and 25 micrometer. Haze development within the crater varies from the third day to the fourteenth day according to the depth and the roughness of the crater. Histologic sections of the cultured cornea showed complete re- epithelization of the lased area. Loose fibrous tissue is observed filling the ablated space beneath the epithelium. The endothelium appeared unaffected. Conclusions: The intensity and time of haze development appears dependent upon the depth of the ablation. Cultured human corneas may provide useful information regarding the healing process following laser ablation.

  12. Particle formation by infrared laser ablation of MALDI matrix compounds.

    PubMed

    Musapelo, Thabiso; Murray, Kermit K

    2014-07-01

    The concentration and size distribution of particles ablated from the infrared matrix-assisted laser desorption/ionization matrix compounds succinic acid (butanedioic acid), ?-cyano-4-hydroxycinnamic acid, and glycerol were measured using an aerodynamic particle sizer combined with a scanning mobility particle sizer. The two sizing instruments together had a sizing range to from 10?nm to 20?µm. Thin layers of the matrix compounds were irradiated with fluences between 6.0 and 9.5?kJ/m(2) and wavelengths between 2.8 and 3.0?µm. The distribution of particles was characterized by a large concentration of clusters in the 20-nm-diameter range and large component of mass in the range of coarse particle with diameters greater than 1?µm. The wavelength dependence revealed a blue shift for the maximum particle production that is attributed to heating and disruption of the hydrogen bonds in the matrix that shifts the absorption to shorter wavelengths. This blue shift has been observed previously in infrared matrix-assisted laser desorption/ionization. PMID:25044838

  13. Excimer laser ablation for spatially controlled protein patterns

    NASA Astrophysics Data System (ADS)

    Thissen, Helmut; Hayes, Jason P.; Kingshott, Peter; Johnson, Graham; Harvey, Erol C.; Griesser, Hans J.

    2001-11-01

    Two-dimensional control over the location of proteins on surfaces is desired for a number of applications including diagnostic tests and tissue engineered medical devices. Many of these applications require patterns of specific proteins that allow subsequent two-dimensionally controlled cell attachment. The ideal technique would allow the deposition of specific protein patterns in areas where cell attachment is required, with complete prevention of unspecific protein adsorption in areas where cells are not supposed to attach. In our study, collagen I was used as an example for an extracellular matrix protein known to support the attachment of bovine corneal epithelial cells. An allylamine plasma polymer was deposited on a silicon wafer substrate, followed by grafting of poly(ethylene oxide). Two-dimensional control over the surface chemistry was achieved using a 248 nm excimer laser. Results obtained by XPS and AFM show that the combination of extremely low-fouling surfaces with excimer laser ablation can be used effectively for the production of spatially controlled protein patterns with a resolution of less than 1 micrometers . Furthermore, it was shown that bovine corneal epithelial cell attachment followed exactly the created protein patterns. The presented method is an effective tool for a number of in vitro and in vivo applications.

  14. Femtosecond laser ablation molecular isotopic spectrometry for zirconium isotope analysis.

    PubMed

    Hou, Huaming; Chan, George C-Y; Mao, Xianglei; Zorba, Vassilia; Zheng, Ronger; Russo, Richard E

    2015-05-01

    Laser ablation molecular isotopic spectrometry (LAMIS) for rapid isotopic analysis of zirconium at atmospheric pressure was studied with a femtosecond-laser system operated under high repetition rate (1 kHz) and low pulse energy (160 ?J). The temporal evolution of zirconium neutral-atomic and ionic lines, as well as zirconium oxide molecular bands, were studied. Six molecular bands, belonging to the d(3)?-a(3)? (i.e., the ? system) and E(1)?(+)-X(1)?(+) transitions, were observed with appreciable isotopic shifts. The assignments of the isotopic bandheads were first based on theoretical predictions of the band origins and the associated isotopic shifts of various dipole-allowed ZrO electronic transitions, followed by an experimental confirmation with a (94)Zr-enriched ZrO2 sample. In this work, the ?(0,1) band from the d(3)?3-a(3)?3 subsystem was utilized for Zr isotope analysis based on a compromise between the magnitude of isotopic shifts in emission wavelengths, emission strengths, signal-to-background ratios, and spectral interferences. The analysis was performed in a standardless calibration approach; the isotopic information was extracted from the experimentally measured molecular spectra through theoretical spectral fitting. The results demonstrate the feasibility to obtain isotopic information for a spectrally complicated element like zirconium, without the need to use isotopically labeled calibration standards. The availability of comprehensive molecular constants will further improve the analytical accuracy of this standardless calibration approach. PMID:25821993

  15. Integration of multimode waveguides and micromirror couplers in printed circuit boards using laser ablation

    NASA Astrophysics Data System (ADS)

    Van Steenberge, Geert; Geerinck, Peter; Van Put, Steven; Van Daele, Peter

    2004-09-01

    Integration of optical interconnections on a Printed Circuit Board (PCB) is very challenging, as it should remain compatible with existing PCB manufacturing technology based on laminated FR4-substrates and making use of solder-reflow and well-known placement and assembly techniques. In this paper we will describe different technologies being used for integration of such optical interconnections in PCB's. As we will demonstrate, the use of laser ablation, already used in PCB manufacturing for microvia's, is a suitable technique for the fabrication of multimode waveguides and micromirrors to provide optical coupling. Laser ablation is a very flexible technology that is particularly well suited for structuring of polymers because of their excellent UV-absorption properties and highly non-thermal ablation behavior. One of the most critical problems on the integration of optical interconnections in PCB's is coupling the light in and out of the optical plane. Because in our set-up the excimer laser beam can be tilted, the 45 degrees micromirrors can be easily fabricated using laser ablation. The focus is on ablation of waveguides using a frequency tripled Nd-YAG laser and on ablation of 45 degrees facets using a KrF excimer laser. It is shown that these structures can be defined in one single processing step, resulting in a very accurate alignment.

  16. Local wettability tuning with laser ablation redeposits on PDMS

    NASA Astrophysics Data System (ADS)

    van Pelt, Stijn; Frijns, Arjan; Mandamparambil, Rajesh; den Toonder, Jaap

    2014-06-01

    In this paper, we present a method to locally control the wettability behavior of PDMS surfaces by excimer laser ablation. In the ablation process, a micrometer scale roughness is formed in the irradiated regions while a nanometer scale roughness is formed by the redeposits surrounding the irradiated regions. The increase in surface roughness results in a change of the wettability behavior of the PDMS surface. By using a hexagonal pattern and tuning the patterning pitch, two different wetting behaviors were realized. A pitch smaller than 300 ?m resulted in a superhydrophobic surface with an advancing contact angle of ?adv = 165° and a receding contact angle of ?rec = 160°. A pitch between 300 and 500 ?m resulted in a sticky superhydrophobic surface with ?adv = 120-150° and ?rec = 80°. The contact angle hysteresis for the latter was larger than for untreated PDMS resulting in very sticky surfaces with high sliding angles. This gives the method great versatility since the two wetting behaviors are very different. By combining both behaviors, local surface features like pinning sites, non-wetting sites, barriers and guides can all be fabricated by a single method. As an application demonstrator of the method, we show that drops can be caught and released depending on size and tilting angle by creating slippery surfaces with sticky barriers. Additionally, the method is ideal for rapid prototyping as it consist of only a single step. It is a direct write method requiring no lithographic mask. Also the process works in ambient atmosphere, so it can be used for temperature or pressure sensitive applications.

  17. Fabrication of binary Fresnel lenses in PMMA by femtosecond laser surface ablation.

    PubMed

    Vázquez, Rebeca Martínez; Eaton, Shane M; Ramponi, Roberta; Cerullo, Giulio; Osellame, Roberto

    2011-06-01

    We report on the fabrication of binary Fresnel lenses by femtosecond laser surface ablation of poly(methyl methacrylate) (PMMA) substrates. Tight focusing of the laser pulses produced a minimum ablated feature size of 600 nm, enabling the creation of lenses with numerical apertures as high as 0.5 and focal lengths ranging from 500 µm to 5 mm. A precise control of the ablation depth allowed the achievement of a 30% focusing efficiency, close to the maximum theoretical value for this kind of lenses. PMID:21716392

  18. Formation of rubrene nanocrystals by laser ablation in liquids utilizing MAPLE deposited thin films

    NASA Astrophysics Data System (ADS)

    O'Malley, Sean M.; Amin, Mitesh; Borchert, James; Jimenez, Richard; Steiner, Matt; Fitz-Gerald, James M.; Bubb, Daniel M.

    2014-03-01

    Nanoparticles (NPs) of the organic semiconductor rubrene were formed utilizing the laser ablation in liquids (LAL) method. Thin-films deposited by Matrix Assisted Pulsed Laser Evaporation (MAPLE) served as the ablation targets. We note in the case of amorphous films targets, the absorbed energy is below the threshold value needed for ablation; though polycrystalline films irradiated under the same LAL conditions result in ejecta. It is suggested this stems from an increase in the effective absorption through light trapping within crystalline domains. An observed red-shift in the absorption edge is attributed to the polar aqueous environment and to the crystalline phase.

  19. Fabrication of nanoparticles and nanostructures using ultrafast laser ablation of silver with Bessel beams

    NASA Astrophysics Data System (ADS)

    Krishna Podagatlapalli, G.; Hamad, Syed; Ahamad Mohiddon, Md; Venugopal Rao, S.

    2015-03-01

    Ablation of silver targets immersed in double distilled water (DDW)/acetone was performed with first order, non-diffracting Bessel beams generated by focusing ultrashort Gaussian pulses (~2 and ~40?fs) through an Axicon. The fabricated Ag dispersions were characterized by UV-visible absorption spectroscopy, transmission electron microscopy and the nanostructured Ag targets were characterized by field emission scanning electron microscopy. Ag colloids prepared with ~2?ps laser pulses at various input pulse energies of ~400, ~600, ~800 and ~1000?µJ demonstrated similar localized surface plasmon resonance (LSPR) peaks appearing near 407?nm. Analogous behavior was observed for Ag colloids prepared in acetone and ablated with ~40?fs pulses, wherein the LSPR peak was observed near 412?nm prepared with input energies of ~600, ~800 and ~1000?µJ. Observed parallels in LSPR peaks, average size of NPs, plasmon bandwidths are tentatively explained using cavitation bubble dynamics and simultaneous generation/fragmentation of NPs under the influence of Bessel beam. Fabricated Ag nanostructures in both the cases demonstrated strong enhancement factors (>106) in surface enhanced Raman scattering studies of the explosive molecule CL-20 (2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) at 5??M concentration.

  20. Laser-launched flyer plate and confined laser ablation for shock wave loading: validation and applications.

    PubMed

    Paisley, Dennis L; Luo, Sheng-Nian; Greenfield, Scott R; Koskelo, Aaron C

    2008-02-01

    We present validation and some applications of two laser-driven shock wave loading techniques: laser-launched flyer plate and confined laser ablation. We characterize the flyer plate during flight and the dynamically loaded target with temporally and spatially resolved diagnostics. With transient imaging displacement interferometry, we demonstrate that the planarity (bow and tilt) of the loading induced by a spatially shaped laser pulse is within 2-7 mrad (with an average of 4+/-1 mrad), similar to that in conventional techniques including gas gun loading. Plasma heating of target is negligible, in particular, when a plasma shield is adopted. For flyer plate loading, supported shock waves can be achieved. Temporal shaping of the drive pulse in confined laser ablation allows for flexible loading, e.g., quasi-isentropic, Taylor-wave, and off-Hugoniot loading. These techniques can be utilized to investigate such dynamic responses of materials as Hugoniot elastic limit, plasticity, spall, shock roughness, equation of state, phase transition, and metallurgical characteristics of shock-recovered samples. PMID:18315311

  1. Laser-launched flyer plate and confined laser ablation for shock wave loading: Validation and applications

    SciTech Connect

    Paisley, Dennis L.; Luo Shengnian; Greenfield, Scott R.; Koskelo, Aaron C. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2008-02-15

    We present validation and some applications of two laser-driven shock wave loading techniques: laser-launched flyer plate and confined laser ablation. We characterize the flyer plate during flight and the dynamically loaded target with temporally and spatially resolved diagnostics. With transient imaging displacement interferometry, we demonstrate that the planarity (bow and tilt) of the loading induced by a spatially shaped laser pulse is within 2-7 mrad (with an average of 4{+-}1 mrad), similar to that in conventional techniques including gas gun loading. Plasma heating of target is negligible, in particular, when a plasma shield is adopted. For flyer plate loading, supported shock waves can be achieved. Temporal shaping of the drive pulse in confined laser ablation allows for flexible loading, e.g., quasi-isentropic, Taylor-wave, and off-Hugoniot loading. These techniques can be utilized to investigate such dynamic responses of materials as Hugoniot elastic limit, plasticity, spall, shock roughness, equation of state, phase transition, and metallurgical characteristics of shock-recovered samples.

  2. Ablation dynamics and shock wave expansion during laser processing of CFRP with ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Wiedenmann, Margit; Haist, Christoph; Freitag, Christian; Onuseit, Volkher; Weber, Rudolf; Graf, Thomas

    2014-03-01

    Carbon fibre reinforced plastics (CFRP) have a large potential in the automotive lightweight construction due to their low density and high mechanical stability. Compared with today's laser processing methods of metals the main issues in laser processing of CFRP are the very differing thermal, optical and mechanical properties of the components. To understand the process in detail, the ablation process of CFRP with ultrashort laser pulses was investigated. The shock wave and the vapor resulting from processing with single laser pulses were recorded. Shadow photography and luminescence photography with an ultra-high-speed camera was used to show the ablation process with a temporary resolution of up to 3 ns. The field of view was 250 ?m × 250 ?m. An ultrashort laser pulse with pulse duration of 4 ps and a wavelength of 800 nm was focused onto the workpiece. The energy content of the shock wave was calculated from the resulting images. The energy content of the shock wave was about 20 % of the incident energy and the speed of propagation of the shock wave was more than 2000 m/s. The high intensities in the range of 1013 W/cm2 lead to formation of a plasma plume which was clearly seen in the shadow photography images.

  3. Initial stage of laser ablation of LiCaAlF6 single crystal under F2 laser irradiation

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Y.; Narazaki, A.; Sato, T.; Kurosaki, R.; Niino, H.; Sato, H.; Fukuda, T.

    Initial stage of F2 laser ablation of LiCaAlF6 single crystal was investigated for clarifying the possibility of applying this wide bandgap fluoride crystal to vacuum ultraviolet (VUV) optical components. The ablation threshold, determined by the appearance of line emission from ablated species, was approximately 2 Jcm-2pulse-1, similar to that of VUV grade CaF2 single crystal. The laser-induced damage on the front surface of LiCaAlF6 was faint, though adhesion of aggregated particulates of several microns was observed.

  4. Experimental study on 785?nm femtosecond laser ablation of sapphire in air

    NASA Astrophysics Data System (ADS)

    Shaheen, M. E.; Gagnon, J. E.; Fryer, B. J.

    2015-06-01

    Changes in surface morphology and ablation rate induced on sapphire were investigated after interaction with femtosecond laser pulses in air at variable fluence (2 to 77?J?cm?2) and repetition rate (10 to 1000?Hz). Multiple laser pulses at a wavelength of 785?nm and pulse width of 130?fs were fired at the surface of sapphire to produce craters whose depth, size and morphology were evaluated using optical and scanning electron microscopy. Ablation rate was found to depend on laser fluence, number of laser pulses and repetition rate. A rapid increase in ablation rate with fluence was observed for fluences lower than 5.9?J?cm?2, followed by a slow increase up to fluence of 40.7?J?cm?2. A drop in ablation rate occurred at fluence greater than 40.7?J?cm?2. Craters produced at high repetition rate (1000?Hz) at fluence of 11.8?J?cm?2 were deeper than those produced at low repetition rate (10?Hz) during the first 40 to 50 pulses. The situation was reversed for craters produced by greater than 50 laser pulses. The drop in ablation rate observed at high fluence and repetition rate can be attributed to attenuation of the laser energy due to plasma and particle shielding that result from interactions with the laser-generated particles that cannot be completely removed from the ablated crater. Defocusing effects associated with the non-equilibrium ionization of air which causes a divergence to the laser beam and consequently a reduction in the laser intensity at the sample surface can be another reason for the observed drop in the ablation rate at high fluence.

  5. Emission intensity modulation of radio-frequency helium glow-discharge emission source by laser ablation.

    PubMed

    Matsuta, Hideyuki; Naeem, Tariq M; Wagatsuma, Kazuaki

    2003-06-01

    A novel emission excitation source comprising a high repetition rate diode-pumped Q-switched Nd:YAG laser and a Grimm-style glow-discharge lamp is described. Laser-ablated atoms are introduced into the He glow discharge plasma, which then give emission signals. By using phase-sensitive detection with a lock-in amplifier, the emission signal modulated by the pulsed laser can be detected selectively. It is possible to estimate only the emission intensity of sample atoms ablated by laser irradiation with little interference from the other species in the plasma. PMID:12834217

  6. Applications of lasers to the solution of environmental problems

    SciTech Connect

    Allen, L.; Pang, H.-M.; Edelson, M.C.

    1995-12-31

    This presentation will focus on current work in the Ames Laboratory where laser ablation is being used for both analytical sampling and metal surface cleaning. Examples will be presented demonstrating the utility of optical spectroscopy for monitoring laser ablation processes.

  7. Multimodal optical characterisation of collagen photodegradation by femtosecond infrared laser ablation.

    PubMed

    Manickavasagam, A; Hirvonen, L M; Melita, L N; Chong, E Z; Cook, R J; Bozec, L; Festy, F

    2014-12-01

    Collagen is a structural component of the human body, as a connective tissue it can become altered as a result of pathophysiological conditions. Although the collagen degradation mechanism is not fully understood, it plays an important role in ageing, disease progression and applications in therapeutic laser treatments. To fully understand the mechanism of collagen alteration, in our study photo-disruptive effects were induced in collagen I matrix by point-irradiation with a femtosecond Ti-sapphire laser under controlled laser ablation settings. This was followed by multi-modal imaging of the irradiated and surrounding areas to analyse the degradation mechanism. Our multi-modal methodology was based on second harmonic generation (SHG), scanning electron microscope (SEM), autofluorescence (AF) average intensities and the average fluorescence lifetime. This allowed us to quantitatively characterise the degraded area into four distinct zones: (1) depolymerised zone in the laser focal spot as indicated by the loss of SHG signal, (2) enhanced crosslinking zone in the inner boundary of the laser induced cavity as represented by the high fluorescence ring, (3) reduced crosslinking zone formed the outer boundary of the cavity as marked by the increased SHG signal and (4) native collagen. These identified distinct zones were in good agreement with the expected photochemical changes shown using Raman spectroscopy. In addition, imaging using polarisation-resolved SHG (p-SHG) revealed both a high degree of fibre re-orientation and a SHG change in tensor ratios around the irradiation spot. Our multi-modal optical imaging approach can provide a new methodology for defining distinct zones that can be used in a clinical setting to determine suitable thresholds for applying safe laser treatments without affecting the surrounding tissues. Furthermore this technique can be extended to address challenges observed in collagen based tissue engineering and used as a minimally invasive diagnostic tool to characterise diseased and non-diseased collagen rich tissues. PMID:25318007

  8. Ablation of ionic crystals induced by capillary-discharge XUV laser

    NASA Astrophysics Data System (ADS)

    Pira, Peter; Burian, Tomáš; Vyšín, Ludék; Chalupský, Jaromír; Lan?ok, Ján; Wild, Jan; St?ižík, Michal; Zelinger, Zden?k; Rocca, Jorge J.; Juha, Libor

    2011-06-01

    Single crystals of two fluorides (LiF and CaF2) and a tungstate (PbWO4) were irradiated by nanosecond pulses of 46.9- nm radiation provided by 10-Hz capillary-discharge Ne-like Ar laser (CDL). The damage threshold was determined in LiF using the CDL beam focused by a Sc/Si multilayer-coated spherical mirror. Irradiated samples have been investigated by Nomarski (DIC - Differential Interference Contrast) microscopy and optical (WLI - white light intereferometry) profiler. After an exposure by a certain number of CDL pulses, an ablation rate can be calculated from WLI measured depth of the crater created by the XUV ablation. Potential use of XUV ablation of ionic crystals in pulsed laser deposition (PLD) of thin layers of such a particular material, which is difficult to ablate by conventional UV-Vis- NIR lasers, is discussed in this contribution.

  9. Transmission of 1064 nm laser radiation during ablation with an ultra-short pulse laser (USPL) system

    NASA Astrophysics Data System (ADS)

    Schelle, Florian; Meister, Jörg; Oehme, Bernd; Frentzen, Matthias

    2012-01-01

    During ablation of oral hard tissue with an USPL system a small amount of the incident laser power does not contribute to the ablation process and is being transmitted. Partial transmission of ultra-short laser pulses could potentially affect the dental pulp. The aim of this study was to assess the transmission during ablation and to deduce possible risks for the patient. The study was performed with an Nd:YVO4 laser, emitting pulses with a duration of 8 ps at a wavelength of 1064 nm. A repetition rate of 500 kHz and an average power of 9 W were chosen to achieve high ablation efficiency. A scanner system created square cavities with an edge length of 1 mm. Transmission during ablation of mammoth ivory and dentin slices with a thickness of 2 mm and 5 mm was measured with a power meter, placed directly beyond the samples. Effects on subjacent blood were observed by ablating specimens placed in contact to pork blood. In a separate measurement the temperature increase during ablation was monitored using an infrared camera. The influence of transmission was assessed by tuning down the laser to the corresponding power and then directly irradiating the blood. Transmission during ablation of 2 mm specimens was about 7.7% (ivory) and 9.6% (dentin) of the incident laser power. Ablation of specimens directly in contact to blood caused coagulation at longer irradiation times (t~18s). Direct irradiation of blood with the transmitted power provoked bubbling and smoke formation. Temperature measurements identified heat generation as the main reason for the observed coagulation.

  10. Laser ablation and contact formation for Cu-plated large area C-silicon industrial solar cells

    Microsoft Academic Search

    J. L. Herna?ndez; C. Allebe?; L. Tous; J. John; J. Poortmans

    2010-01-01

    In this work we demonstrate the successful implementation of laser ablation of SiNx ARC to contact high ohmic emitters up to 120 ?\\/sq with an advanced metallization on large area substrates. We propose Suns-Voc measurements as a fast and effective method to characterize the potential laser damage. We look at the laser ablation factors that can compromise the solar cell

  11. Direct femtosecond laser ablation of copper with an optical vortex beam K. K. Anoop,1,2

    E-print Network

    Marrucci, Lorenzo

    Direct femtosecond laser ablation of copper with an optical vortex beam K. K. Anoop,1,2 R September 2014) Laser surface structuring of copper is induced by laser ablation with a femtosecond optical- ing micro- and/or nano-structured surface for any specific application. VC 2014 AIP Publishing LLC

  12. A Final Report on the Oxidation and Composition Gradients of Aged Painting Varnishes Studied with Pulsed UV Laser Ablation

    NASA Astrophysics Data System (ADS)

    Theodorakopoulos, C.; Zafiropulos, Vassilis; Boon, J. J.

    This paper discusses findings that establish the ageing-induced compositional and crosslinking gradients across the depth-profiles of two accelerated aged natural resin varnishes: dammar and mastic, which are commonly applied to paintings. Profile measurements of laser-processed films using a KrF excimer laser, as well as online measurements of the C2 emission by laser-induced breakdown spectroscopy (LIBS), showed a significant reduction of the ablation step and ablation yield with depth, respectively. Direct temperature mass spectrometry (DTMS) showed that the oxidation products formed upon ageing were gradually eliminated across depth, which affected the depth-wise optical properties of the films studied by UV/VIS spectrophotometry. The total ion currents of the DTMS in the electron ionisation mode (EI, 16 eV) demonstrated also a gradual reduction of the pyrolysis yield which corresponded to a gradual depth-wise elimination of the high MW fractions that was confirmed by size exclusion chromatography (SEC). The gradients were established also by surface analyses, such as matrix-assisted laser desorption/ionisation-time-offlight- MS (MALDI-TOF-MS) and attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR), which indicated that the action of the KrF excimer laser is non-destructive to the varnish when optimal fluences are used for the laser cleaning process. The extracted data enabled the quantification of the compositional gradients and unraveled a significant feature of natural resins, which would not have been possible without the use of KrF excimer lasers.

  13. Surface ablation of PLLA induced by KrF excimer laser

    NASA Astrophysics Data System (ADS)

    Slepi?ka, P.; Michaljani?ová, I.; Sajdl, P.; Fitl, P.; Švor?ík, V.

    2013-10-01

    The surface characterization of PLLA (poly-L-lactic-acid) and its ablation due to excimer laser treatment is introduced in this paper. The main focus is to determine surface wettability and morphology changes in combination with changes of surface chemistry. The ablation loss and the determination of ablation threshold were used to study the biopolymer stability when treated to different laser fluences and pulse counts. The surface polarity was estimated using goniometry. AFM (atomic force microscopy) was used to determine the polymer surface morphology and roughness. The excimer laser has a strong effect on the polymer ablation. The thickness loss is strongly dependent on the laser fluence and number of pulses. For the fluences up to 30 mJ cm-2 and 6000 pulses achieved ablation about 5 ?m. The glass transition temperature and melting point were determined for the pristine and laser treated films. The increasing pulsed laser fluence leads to the major changes in roughness and morphology. The surface chemistry depends strongly on number of laser pulses.

  14. Synthesis and characterization of gold graphene composite with dyes as model substrates for decolorization: A surfactant free laser ablation approach

    NASA Astrophysics Data System (ADS)

    Sai Siddhardha, R. S.; Lakshman Kumar, V.; Kaniyoor, Adarsh; Sai Muthukumar, V.; Ramaprabhu, S.; Podila, Ramakrishna; Rao, A. M.; Ramamurthy, Sai Sathish

    2014-12-01

    A facile surfactant free laser ablation mediated synthesis (LAMS) of gold-graphene composite is reported here. The material was characterized using transmission electron microscopy, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, powdered X-ray diffraction, Raman spectroscopy, Zeta potential measurements and UV-Visible spectroscopic techniques. The as-synthesized gold-graphene composite was effectively utilized as catalyst for decolorization of 4 important textile and laser dyes. The integration of gold nanoparticles (AuNPs) with high surface area graphene has enhanced the catalytic activity of AuNPs. This enhanced activity is attributed to the synergistic interplay of pristine gold's electronic relay and ?-? stacking of graphene with the dyes. This is evident when the Rhodamine B (RB) reduction rate of the composite is nearly twice faster than that of commercial citrate capped AuNPs of similar size. In case of Methylene blue (MB) the rate of reduction is 17,000 times faster than uncatalyzed reaction. This synthetic method opens door to laser ablation based fabrication of metal catalysts on graphene for improved performance without the aid of linkers and surfactants.

  15. Comparison of Solution-Based versus Laser Ablation Inductively Coupled Plasma Mass Spectrometry for Analysis of Larval Fish

    E-print Network

    Comparison of Solution-Based versus Laser Ablation Inductively Coupled Plasma Mass Spectrometry) inductively coupled plasma mass spectrometry (ICPMS) to quantify the otolith elemental composition of larval

  16. Picosecond laser ablation of SiO 2 layers on silicon substrates

    Microsoft Academic Search

    Sonja Hermann; Nils-Peter Harder; Rolf Brendel; Dirk Herzog; Heinz Haferkamp

    2010-01-01

    In this work, we report on laser ablation of thermally grown SiO2 layers from silicon wafer substrates, employing an 8–9 ps laser, at 1064 (IR), 532 (VIS) and 355 nm (UV) wavelengths. High-intensity\\u000a short-pulse laser radiation allows direct absorption in materials with bandgaps higher than the photon energy. However, our\\u000a experiments show that in the intensity range of our laser pulses (peak

  17. Toward laser ablation Accelerator Mass Spectrometry of actinides

    SciTech Connect

    R. C. Pardo; F. G. Kondev; S. Kondrashev; C. Nair; T. Palchan; R. Scott; D. Seweryniak; R. Vondrasek; M. Paul; P. Collon; C. Deibel; M. Salvatores; G. Palmiotti; J. Berg; J. Fonnesbeck; G. Imel

    2013-01-01

    A project to measure neutron capture cross sections of a number of actinides in a reactor environment by Accelerator Mass Spectrometry (AMS) at the ATLAS facility of Argonne National Laboratory is underway. This project will require the precise and accurate measurement of produced actinide isotopes in many (>30) samples irradiated in the Advanced Test Reactor at Idaho National Laboratory with neutron fluxes having different energy distributions. The AMS technique at ATLAS is based on production of highlycharged positive ions in an electron cyclotron resonance (ECR) ion source followed by acceleration in the ATLAS linac and mass-to-charge (m/q) measurement at the focus of the Fragment Mass Analyzer. Laser ablation was selected as the method of feeding the actinide material into the ion source because we expect it will have higher efficiency and lower chamber contamination than either the oven or sputtering techniques, because of a much narrower angular distribution of emitted material. In addition, a new multi-sample holder/changer to allow quick change between samples and a computer-controlled routine allowing fast tuning of the accelerator for different beams, are being developed. An initial test run studying backgrounds, detector response, and accelerator scaling repeatability was conducted in December 2010. The project design, schedule, and results of the initial test run to study backgrounds are discussed.

  18. Amorphous diamond: a unique product of laser ablation

    NASA Astrophysics Data System (ADS)

    Collins, Carl B., Jr.; Davanloo, Farzin

    1996-04-01

    Composed of sp3 bonded nodules of carbon, amorphic diamond films are deposited in vacuum onto almost any substrate by condensing carbon ions carrying keV energies. These multiply charged ions are obtained from the laser ablation of graphite at intensities in excess of 1011 W cm-2. The high energy of condensation provides both for the chemical bonding of such films to a wide variety of substrates and for low values of residual compressive stress, 0.6 - 0.8 GPa. On selected films hardness cannot be measured because of deformation of the diamond indenter and only a lower limit of 78 GPa can be reported. Coatings of 2 - 5 micrometer thicknesses have extended lifetimes of materials such as Si, Ti, ZnS, ZnSe, Ge and stainless steel against the erosive wear from high-speed particles by factors of tens to thousands. The mechanical properties of amorphic diamond films are further enhanced by a low coefficient of friction of about 0.1. The combination of these mechanical properties seems to make amorphic diamond an attractive material for use as a protective coating in current industrial applications. Deposited upon silicon, quartz or sapphire, amorphic diamond films have interesting electrical properties including a very high coefficient of emissivity.

  19. Toward laser ablation Accelerator Mass Spectrometry of actinides

    NASA Astrophysics Data System (ADS)

    Pardo, R. C.; Kondev, F. G.; Kondrashev, S.; Nair, C.; Palchan, T.; Scott, R.; Seweryniak, D.; Vondrasek, R.; Paul, M.; Collon, P.; Deibel, C.; Youinou, G.; Salvatores, M.; Palmotti, G.; Berg, J.; Fonnesbeck, J.; Imel, G.

    2013-01-01

    A project to measure neutron capture cross sections of a number of actinides in a reactor environment by Accelerator Mass Spectrometry (AMS) at the ATLAS facility of Argonne National Laboratory is underway. This project will require the precise and accurate measurement of produced actinide isotopes in many (>30) samples irradiated in the Advanced Test Reactor at Idaho National Laboratory with neutron fluxes having different energy distributions. The AMS technique at ATLAS is based on production of highly-charged positive ions in an electron cyclotron resonance (ECR) ion source followed by acceleration in the ATLAS linac and mass-to-charge (m/q) measurement at the focus of the Fragment Mass Analyzer. Laser ablation was selected as the method of feeding the actinide material into the ion source because we expect it will have higher efficiency and lower chamber contamination than either the oven or sputtering techniques, because of a much narrower angular distribution of emitted material. In addition, a new multi-sample holder/changer to allow quick change between samples and a computer-controlled routine allowing fast tuning of the accelerator for different beams, are being developed. An initial test run studying backgrounds, detector response, and accelerator scaling repeatability was conducted in December 2010. The project design, schedule, and results of the initial test run to study backgrounds are discussed.

  20. Phase and composition changes of titanite during laser ablation inductively coupled plasma mass spectrometry analysis.

    PubMed

    Fliegel, Daniel; Klementova, Mariana; Kosler, Jan

    2010-05-15

    Changes in phase and chemical composition of the mineral titanite (monoclinic CaTiSiO(5)) during laser ablation and plasma-aerosol interaction were investigated using electron diffraction and electron microbeam X-ray analysis with transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Laser ablation of titanite with a solid state 213 nm nanosecond laser generates a bimodal aerosol consisting of condensed nanoparticles and spherical micrometer-sized particles. The two types of particles produced by laser ablation are amorphous on the scale resolvable by the electron diffraction. The ratio of Ca-Si-Ti does not change significantly during laser ablation. Aerosol of titanite particles introduced into the ICP and collected after interaction with the plasma contains nanometer-sized particles of a condensate and spherical micrometer-sized particles with a molten surface. The condensed particles are enriched in silicon whereas the spherical micrometer-sized particles show a deficiency in Si relative to the titanite composition. During laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) analysis of titanite, Si and Ti showed positive and negative fractionation trends relative to Ca, respectively. This is consistent with the observed chemical composition changes of the titanite aerosol within the ICP. This study links for the first time the chemical and phase changes of a sample within the ICP to the elemental fractionation during LA-ICPMS. PMID:20423052

  1. Efficiency and Plume Dynamics for Mid-IR Laser Ablation of Cornea

    NASA Astrophysics Data System (ADS)

    Jayasinghe, Aroshan; Ivanov, Borislav; Hutson, M. Shane

    2009-03-01

    This paper reports ablation experiments on porcine corneal tissue using the Vanderbilt Mark III Free Electron Laser (FEL) and a tabletop Raman-shifted Alexandrite laser. These experiments were designed to test previous models that suggested wavelength and intensity dependent ablation mechanisms. In one test, we compare ablation efficiency and plume dynamics for two FEL wavelengths (?=2.77, 6.45 ?m) chosen such that different components of the tissue matrix act as the primary chromophore (water or protein respectively), while keeping the total absorption constant. We find small differences in ablation efficiency (with slightly more efficient ablation at 2.77 ?m); no difference in shockwave propagation; and slightly more particulate matter in the plume at 6.45 ?m. In a second test, we find that the Raman-shifted Alexandrite laser has similar ablation efficiency to the FEL in the 6-7 ?m range -- despite a ˜500-fold higher intensity. Although these results do not confirm the previous model predictions, the findings do suggest that the Raman-shifted laser can be a viable alternative to the FEL for surgical applications.

  2. Comparison between geometrically focused pulses versus filaments in femtosecond laser ablation of steel and titanium alloys

    NASA Astrophysics Data System (ADS)

    Valenzuela, Anthony; Munson, Chase; Porwitzky, Andrew; Weidman, Matthew; Richardson, Martin

    2014-08-01

    Kerr self-focusing of high-power ultrashort laser pulses in atmosphere may result in a structure or structures of high intensity that can propagate over long distances with little divergence. Filamentation has garnered significant interest in the nonlinear optics community due to its unique properties. Salient features of filaments include a central region of intense laser power (greater than the ionization threshold of the propagation medium) and a low temperature plasma column that lasts up to nanoseconds in duration after the passage of the laser pulse. Steel and titanium samples are ablated by filaments and by sharply focused sub-picosecond laser pulses. We then performed metrology on the samples to compare the ablation features in addition to modeling of the plasma ablation process. Ablation with filaments leads to a wider range of material responses as compared to ablation with sharply focused pulse. This results in potential complications for applications of filament ablation that depends on the rate of material removal and spectroscopic analysis.

  3. Femtosecond laser ablation of dielectric materials in the optical breakdown regime: Expansion of a transparent shell

    SciTech Connect

    Garcia-Lechuga, M.; Siegel, J., E-mail: j.siegel@io.cfmac.csic.es; Hernandez-Rueda, J.; Solis, J. [Laser Processing Group, Instituto de Optica, Serrano 121, 28006 Madrid (Spain)

    2014-09-15

    Phase transition pathways of matter upon ablation with ultrashort laser pulses have been considered to be understood long-since for metals and semiconductors. We provide evidence that also certain dielectrics follow the same pathway, even at high pulse energies triggering optical breakdown. Employing femtosecond microscopy, we observe a characteristic ring pattern within the ablating region that dynamically changes for increasing time delays between pump and probe pulse. These transient Newton rings are related to optical interference of the probe beam reflected at the front surface of the ablating layer with the reflection at the interface of the non-ablating substrate. Analysis of the ring structure shows that the ablation mechanism is initiated by a rarefaction wave leading within a few tens of picoseconds to the formation of a transparent thin shell of reduced density and refractive index, featuring optically sharp interfaces. The shell expands and eventually detaches from the solid material at delays of the order of 100 ps.

  4. Formation of wide bandgap cerium oxide nanoparticles by laser ablation in aqueous solution

    NASA Astrophysics Data System (ADS)

    Takeda, Yoshihiro; Mafuné, Fumitaka

    2014-04-01

    Cerium oxide nanoparticles were produced by laser ablation in an aqueous solution. Submicron-sized cerium oxide particles were size-reduced by pulsed-laser irradiation into those having diameters of 3.6 nm. It was found that the bandgap of the nanoparticle was larger and the Ce3+ concentration within it was higher than those prepared by other conventional methods. These characteristic structures are likely to originate from additional defect sites in the nanoparticles produced by laser ablation, where O2- ions have a lower coordination with Ce ions, resulting in removal of O atoms and reduction of Ce4+ into Ce3+.

  5. Effect of varying laser parameters on in-vitro ablation of porcine sclera with Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Pergadia, Vani R.; Vari, Sandor G.; Shi, Wei-Qiang; Fishbein, Michael C.; Grundfest, Warren S.

    1993-06-01

    The effect of various laser parameters on the ablation rate and the resulting thermal damage on porcine scleral tissue by the Ho:YAG laser was tested. We compared the ablation rate and the thermal damage with varying fluences, fiber core diameters and pulse durations. A Ho:YAG laser operating at a wavelength of 2.1 micrometers at a repetition rate of 2 Hz was used. The ablation rate for the tissue was calculated as the ratio of the number of pulses needed to perforate the sample to the sample thickness (micrometers /pulse +/- standard deviation). The lateral thermal damage depths were quantified by ocular micrometry. Our results suggest that with the Ho:YAG (2.1 micrometers ) laser the ablation rate increases linearly with radiant exposure, but the change in radiant exposure does not significantly affect thermal damage. Different pulse durations generate small changes in ablation rate, but no change in thermal damage. An increase in the irradiated area enhances the ablation rate and thermal damage.

  6. Micro-spatial variations of heavy metals in the teeth of walrus as determined by laser ablation ICP-MS: The potential for reconstructing a history of metal exposure

    Microsoft Academic Search

    R. D. Evans; P. Richner; P. M. Outridge

    1995-01-01

    This study explored the possibility of using laser ablation inductively-coupled plasma-mass spectroscopy to measure trace metals and other elements within the annual growth layers of the teeth of walrus harvested from the Canadian Arctic. Using sample ablation “footprints” of 125 µm diameter on transects across the exposed cross-sections of teeth, this technique detected Pb, Cu, Zn and Sr, but not

  7. Laser ablation ignition of premixed methane and oxygen-enriched air mixtures using a tantalum target.

    PubMed

    Li, Xiaohui; Yu, Xin; Fan, Rongwei; Yu, Yang; Liu, Chang; Chen, Deying

    2014-01-01

    We report the laser ablation ignition of premixed methane and oxygen-enriched air mixtures using a tantalum target. The minimum laser pulse energy (MPE) of the ablation ignition was obtained as 2-4 mJ, which was reduced by one order of magnitude compared with that of the direct laser-induced gas breakdown ignition. The ignition time of the ablation ignition was investigated for the first time, to our best knowledge, by measuring the emission signal profiles due to the successfully ignited flames, and an ignition time as short as ~50 ?s was obtained. The reduction in MPE will promote the miniaturization and, thus, the practical applications of laser ignition systems. PMID:24365842

  8. Processing condition influence on the characteristics of gold nanoparticles produced by pulsed laser ablation in liquids

    NASA Astrophysics Data System (ADS)

    Nikov, R. G.; Nikolov, A. S.; Nedyalkov, N. N.; Atanasov, P. A.; Alexandrov, M. T.; Karashanova, D. B.

    2013-06-01

    A study is presented of Au nanoparticles (NPs) created by nanosecond pulsed laser ablation of a solid target in double distilled water. The influence was examined of the laser wavelength on the size, shape and optical properties of the resulting NPs. Three different wavelengths: the fundamental (? = 1064 nm), second (?SHG = 532) and third (?THG = 355) harmonic of a Nd:YAG laser at the same fluence were utilized to produce various colloids. Ablation at the wavelength of 532 nm was investigated in more detail to reveal the influence of self-absorption by the already created NPs on their characteristics. The colloid produced was irradiated by ?irrad = 532 nm (laser energy 40 mJ) at different times up to 25 min after the end of ablation. The initial structure of welded NPs forming wires was modified. Transmission electron microscopy and optical transmission measurements were used to evaluate the shape and size distribution of the NPs.

  9. Laser ablation of micro-photonic structures for efficient light collection and distribution

    NASA Astrophysics Data System (ADS)

    Shang, Xiaobing; Desmet, Andres; De Smet, Jelle; Joshi, Pankaj; Cuypers, Dieter; Van Put, Steven; Van Steenberge, Geert; Vervaeke, Michael; Thienpont, Hugo; De Smet, Herbert

    2015-06-01

    In this work we report the fabrication of polymer micro-photonic gratings for use in liquid-crystal based actively tunable electro-optic components. The gratings are produced by moving the sample surface sideways across a perpendicularly impinging KrF excimer laser beam (???=??248 nm), which is shaped by specially designed triangular and trapezoidal masks. To obtain correctly dimensioned and smooth grating surfaces, different materials (SU-8, polycarbonate, Epoclad and Epocore) are subjected to the laser ablation with optimized laser processing parameters. The resulting grating structures on Epocore exhibit the best surface roughness and dimensional fidelity. Optionally, spacers for maintaining the cell gap of the superimposed liquid crystal layer can also be fabricated in the same process. Two different methods were demonstrated: overlapping ablation and double mask ablation. Micro-grating structures were produced that deflect a monochromatic (543 nm) laser beam to the theoretically predicted 11th order with an angle of 7°.

  10. PHYSICAL REVIEW LETTERS Evidence for the Thermal Nature of Laser-Induced Polymer Ablation

    Microsoft Academic Search

    D. Dijkkamp; A. S. Gozdz; T. Venkatesan; X. D. Wu

    We report the results of an experiment designed to study the role of thermal processes in pulsed- laser-induced ablation of polymers. Using nonabsorbing polymer films on absorbing substrates and time-resolved reflectivity measurements, we show that laser-induced nanosecond heat pulses can cause rapid decomposition of polymers. This process exhibits all properties of so-called \\

  11. Page 2 of 55 Low-cost photomask fabrication using laser ablation

    E-print Network

    -thick) on float glass substrate. Then a nitrocellulose lacquer, serving as a self-developing resist, is spin hydrofluoric acid. Both nitrocellulose lacquer characterization and laser parameters are discussed; Photomask; Laser ablation; Patterning; Nitrocellulose lacquer. hal-01060034,version1-2Sep2014 Author

  12. A multicenter, randomized, prospective study of endoscopic laser ablation versus transurethral resection of the prostate

    Microsoft Academic Search

    Ken Anson; Jan Nawrocki; John Buckley; Chris Fowler; Roger Kirby; William Lawrence; Peter Paterson; Graham Watson

    1995-01-01

    ObjectivesTo assess the safety and efficacy of endoscopic laser ablation of the prostate (ELAP), performed with the Urolase fiber and the neodymium:yttrium-aluminum-garnet laser, compared to transurethral resection of the prostate (TURP) in patients with bladder outflow obstruction secondary to benign prostatic hyperplasia (BPH).

  13. A Low Diffraction Laser Beam as Applied to Polymer Ablation Xuanhui Lu*

    E-print Network

    Yao, Y. Lawrence

    microelectronics and precision medical device applications [4,5,6]. The quality is * Research Scientist that of a Gaussian beam. The effects of the improved beam quality on laser ablation process are investigated at the same average power lever. 1. Introduction Laser beam quality plays a role in quality and efficiency

  14. Laser Ablation Electrospray Ionization for Atmospheric Pressure, in Vivo, and Imaging Mass

    E-print Network

    Vertes, Akos

    Laser Ablation Electrospray Ionization for Atmospheric Pressure, in Vivo, and Imaging Mass. For example, atmospheric pressure infrared MALDI (AP IR-MALDI), capable of producing ions from small ionization (DESI),5 desorption atmospheric pressure chemical ionization (DAPCI),6 and matrix- assisted laser

  15. Nanoparticle formation during laser ablation of metals at different pressures of surrounding noble gases

    Microsoft Academic Search

    R. A. Ganeev; G. S. Boltaev; R. I. Tugushev; T. Usmanov

    2010-01-01

    We demonstrate that the nanoparticle formation during laser ablation of metals by short (of a few tens of ps) laser pulses strongly depends on the concentration of surrounding gas. While, at vacuum conditions, nanoparticle formation shows very ``sharp'' atomic force microscope images of aggregated clusters, following with clear appearance of plasmon resonance on the absorption spectra of deposited films, an

  16. Internal structure and expansion dynamics of laser ablation plumes into ambient gases

    E-print Network

    Harilal, S. S.

    Internal structure and expansion dynamics of laser ablation plumes into ambient gases S. S. Harilal 13 December 2002 The effect of ambient gas on the expansion dynamics of the plasma generated by laser together with time resolved emission diagnostics, a triple structure of the plume was observed

  17. Elemental fractionation in ultraviolet laser ablation sampling of igneous silicate minerals relevant to Mars

    Microsoft Academic Search

    M. E Taylor; D. L Blaney; G Cardell

    2000-01-01

    Laser ablation sampling (LAS) has significant potential for remote terrestrial and extraterrestrial applications if fractionation can be understood and controlled. This study focuses on acmite, albite, augite, diopside, forsterite, and labradorite, silicate minerals that are relevant to Mars, Earth, the moon, and asteroids. The minerals were sampled using a frequency-quadrupled Nd:YAG laser and the samples were deposited as films on

  18. Structure property relations of photoreactive polymers designed for laser ablation

    Microsoft Academic Search

    T. Lippert; C. Davida; J. T. Dickinson; M. Hauer; U. Kogelschatz; S. C. Langford; O. Nuyken; C. Phipps; J. Robert; A. Wokaun

    2001-01-01

    The ablation characteristics of various polymers were studied at low fluences, and structure property relations were obtained. The polymers containing the photochemically most active group (triazene) are also the polymers with the lowest threshold of ablation and the highest etch rates, followed by a designed polyester and then polyimide. No pronounced influences of the absorption coefficients, neither ?lin nor ?eff,

  19. Pulsed laser deposition of silk protein: Effect of photosensitized-ablation on the secondary structure in thin deposited films

    NASA Astrophysics Data System (ADS)

    Tsuboi, Yasuyuki; Goto, Masaharu; Itaya, Akira

    2001-06-01

    Silk fibroin is a simple protein expected to have functional applications in medicine and bioelectronics. The primary structure of this protein is quite simple, and the main secondary structures are ?-sheet crystals and amorphous random coils. In the present study, we investigated pulsed laser deposition (PLD) of fibroin with the ?-sheet structures as targets. The primary and secondary structures in films deposited were analyzed using infrared spectroscopy. Normal laser deposition at 351 nm using neat fibroin targets produced thin films of fibroin with a random coiled structure. Ablation was triggered by two-photonic excitation of the peptide chains, which resulted in the destruction of ?-sheet structure in PLD. In order to avoid the two-photonic excitation, we adopted a PLD method utilizing anthracene (5-0.1 wt %) in a photosensitized reaction involving doped fibroin targets. Laser light (351 or 355 nm) was absorbed only by anthracene, which plays an important role converting photon energy to thermal energy with great ablation efficiency. Thin fibroin films deposited by this method had both random coil and ?-sheet structures. As the dopant concentration and laser fluence decreased, the ratio of ?-sheet domain to random coil increased in thin deposited films.

  20. Pulsed laser deposition of silk protein: Effect of photosensitized-ablation on the secondary structure in thin deposited films

    SciTech Connect

    Tsuboi, Yasuyuki; Goto, Masaharu; Itaya, Akira

    2001-06-15

    Silk fibroin is a simple protein expected to have functional applications in medicine and bioelectronics. The primary structure of this protein is quite simple, and the main secondary structures are {beta}-sheet crystals and amorphous random coils. In the present study, we investigated pulsed laser deposition (PLD) of fibroin with the {beta}-sheet structures as targets. The primary and secondary structures in films deposited were analyzed using infrared spectroscopy. Normal laser deposition at 351 nm using neat fibroin targets produced thin films of fibroin with a random coiled structure. Ablation was triggered by two-photonic excitation of the peptide chains, which resulted in the destruction of {beta}-sheet structure in PLD. In order to avoid the two-photonic excitation, we adopted a PLD method utilizing anthracene (5{endash}0.1 wt%) in a photosensitized reaction involving doped fibroin targets. Laser light (351 or 355 nm) was absorbed only by anthracene, which plays an important role converting photon energy to thermal energy with great ablation efficiency. Thin fibroin films deposited by this method had both random coil and {beta}-sheet structures. As the dopant concentration and laser fluence decreased, the ratio of {beta}-sheet domain to random coil increased in thin deposited films. {copyright} 2001 American Institute of Physics.

  1. Growth of ZnO thin films by ultraviolet pulsed-laser ablation: Study of plume dynamics

    NASA Astrophysics Data System (ADS)

    Klini, A.; Manousaki, A.; Anglos, D.; Fotakis, C.

    2005-12-01

    A comparative study is presented on the growth of ZnO thin films by ultraviolet pulsed-laser deposition using nanosecond and femtosecond pulses at 248nm. Different experimental parameters were examined including substrate temperature, oxygen ambient pressure, and laser energy density at the target. At optimum conditions the films grown exhibited high optical transmittance and a preferential orientation along the c axis, both with nanosecond and femtosecond irradiations. However, those produced with the ultrashort laser pulses are composed of smaller dimension crystallites, with higher angular distribution on the substrate and higher roughness, suggesting different film growth mechanism. This was investigated by studying the plume dynamics of the ejected material accompanying laser ablation of the ZnO targets by means of spatially and time-resolved optical emission spectroscopy in order to obtain information on the nature of the ejected species and the distribution of their propagation velocities. Employing irradiation conditions, typically used in the deposition experiments, emission lines assigned to electronically excited neutral zinc atoms (Zn*) were observed both in the case of nanosecond and femtosecond pulses, while the latter additionally gave rise to emission attributable to zinc ions (Zn+*). The mean propagation velocities measured suggest the presence of highly energetic Zn cations in the case of femtosecond ablation, which are likely to be responsible for defect formation on the films, disturbing the smooth growth of crystallites that takes place under nanosecond irradiation, and giving rise to films composed of smaller crystallites with higher mosaicity and roughness.

  2. Size and polydispersity trends found in gold nanoparticles synthesized by laser ablation in liquids.

    PubMed

    Tomko, J; Naddeo, J J; Jimenez, R; Tan, Y; Steiner, M; Fitz-Gerald, J M; Bubb, D M; O'Malley, S M

    2015-07-01

    In this work, the effect of laser fluence on Au nanoparticles synthesized via laser ablation in liquids is studied for 1064 nm irradiation with 25 ps pulses. Particle size and polydispersity is found to display a negative trend with fluences up to ?14 J cm(-2). Erratic size tendencies are observed at low fluences, i.e. slightly above the ablation threshold. This overall behavior is reconciled with recent computational studies and to fluctuations in ablation due to surface morphology. The effectiveness of the commonly used surfactant sodium dodecyl sulfate (SDS) is shown to diminish at higher fluence due to pyrolysis. In addition, shadowgraph imaging of the cavitation bubble is shown as a useful technique for determining the ablation threshold. Our findings are in good agreement with threshold values determined by traditional methods and are comparable to computational values, when differences in pulse duration are taken into account. PMID:26040197

  3. Ultrafast thin-film laser-induced breakdown spectroscopy of doped oxides

    SciTech Connect

    Owens, Travis; Mao, Samuel S.; Canfield, Erin K.; Grigoropoulos, Costas P.; Mao, Xianglei; Russo, Richard E.

    2010-05-01

    Single-shot femtosecond laser induced breakdown spectroscopy (LIBS) has been shown to be an effective means of detecting heavy metal dopants in porous thin films. Traditional LIBS analysis of trace dopants in modern painted surfaces or TiO2 films is difficult due to the broad noisy spectra of the titanium constituent and interference due to the substrate material. Femtosecond laser pulses provide excellent ablation of the target material with little damage to the underlying substrate. In this study a Ti:sapphire femtosecond laser pulse operated at 800 and 266 nm wavelengths and an Nd:YAG nanosecond laser operated at 266 nm were used to ablate 0.15-15 {mu}m films of TiO2 doped with varying amounts of MgO. This application shows excellent detection of Mg down to 60 ppm with little interference by the substrate material.

  4. Laser spectrometry and laser ablation - an ideal solution for the analysis of nuclear materials

    SciTech Connect

    Goodall, P.; Johnson, S.G. [Argonne National Lab., Idaho Falls, ID (United States)

    1996-09-01

    Nuclear materials, consisting primarily of actinides and lanthanides, produce a plethora of emission lines from the ICP. This provides an entertaining problem for the analyst applying ICP-AES. Laser ablation ICP-AES (LA-ICP-AES) offers unique advantages for the analysis of nuclear materials as it allows remote analysis of these materials in heavily shielded environments. The use of high resolution spectrometry, when coupled with LA-ICP-AES, simplifies the spectral chaos normally encountered with these materials. This obviates the requirement for analyte separation which standard ICP-AES instrumentation demands. Examples of the analysis of nuclear fuels and materials used in the reprocessing of that fuel will be presented (e.g., the determination of U, La, Y, Ce and Nd in molten salts.). In addition to bulk (or local) chemical composition, it is also possible to extract isotopic information using high resolution LA-ICP-AES (e.g., the determination of {sup 236}U for the estimation of {open_quotes}burn-up{close_quotes} of {sup 235}U in a nuclear reactor). Laser excited atomic fluorescence (LEAFS) has the advantage of high specificity at the expense of instrumental sophistication but provides one solution to the spectral complexity encountered with nuclear materials. The potential of laser ablation coupled to ICP-LEAFS will be discussed and the determination of lanthanides by LA-ICP-LEAFS described.

  5. Comparison the efficacy of ablative CO2 laser and fractional CO2 laser on the healing of cutaneous leishmaniasis scars

    PubMed Central

    Nilforoushzadeh, Mohammad Ali; Minaravesh, Shahriar; Jaffary, Fariba; Siadat, Amir Hossein; Haftbaradaran, Elaheh

    2014-01-01

    Background: The aim of this study is to compare ablative CO2 laser with fractional CO2 laser on healing of the wound and the size of cutaneous leishmaniasis scars. Materials and Methods: This prospective randomized clinical trial study was done on 120 patients in two groups evaluated in Sedigheh Tahereh Hospital in Isfahan. The patients in case group underwent one session ablative CO2 laser for treatment of leishmaniasis scars and the patients in control group underwent six 3-weeks interval sessions fractional CO2 laser for treatment of leishmaniasis scars. All cases were evaluated from size and other aspects of scar by a questionnaire, and before and 6 months after photos were evaluated by blinded dermatologist. The data collected in the check list was then analyzed by t-test and Chi-square with SPSS 20. Results: There were 60 people in case group and 60 in control group. The mean age was 27.21 ± 11.2. Our results show that fractional CO2 laser is better than ablative CO2 laser in various aspect of treatment of leishmaniasis scars (P < 0.05). Conclusions: Fractional CO2 laser is better than ablative CO2 laser in variants aspect of treatment of leishmaniasis scars. PMID:25625098

  6. 150 MeV Au ion induced modification of Si nanoparticles prepared by laser ablation

    NASA Astrophysics Data System (ADS)

    Saikiran, V.; Vendamani, V. S.; Hamad, S.; Nageswara Rao, S. V. S.; Venugopal Rao, S.; Pathak, A. P.

    2014-08-01

    We have investigated in detail the effects of 150 MeV Au ions irradiation on Si nanoparticles (NPs) synthesized by picosecond laser ablation of single crystal Si wafers in acetone. The formation of Si NPs was confirmed by Raman spectroscopy, transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM) measurements. The size distribution of synthesized NPs was found to be in the range of few nm to 80 nm. These samples were then irradiated with 150 MeV Au ions at various fluences ranging from 1 × 1013 to 1 × 1014 ions/cm2. The effects of ion irradiation on the size and shape of Si NPs were further investigated using TEM, FESEM and micro Raman spectroscopy. From TEM data, we have noticed the reduction in size of NPs with increasing ion irradiation fluence. Furthermore with the increasing fluence we also observed the nucleation of 6-9 nm NPs in the vicinity of bigger NPs where there were no such NPs before ion irradiation. The increase in the FWHM of the Raman peak and its shift towards lower wave number side also suggests that the decrease in NP size is a result of increase in the fluence of irradiation.

  7. Influence of film thickness on laser ablation threshold of transparent conducting oxide thin-films

    NASA Astrophysics Data System (ADS)

    Rung, S.; Christiansen, A.; Hellmann, R.

    2014-06-01

    We report on a comprehensive study of the laser ablation threshold of transparent conductive oxide thin films. The ablation threshold is determined for both indium tin oxide and gallium zinc oxide as a function of film thickness and for different laser wavelengths. By using a pulsed diode pumped solid state laser at 1064 nm, 532 nm, 355 nm and 266 nm, respectively, the relationship between optical absorption length and film thickness is studied. We find that the ablation threshold decreases with increasing film thickness in a regime where the absorption length is larger than the film thickness. In turn, the ablation threshold increases in case the absorption length is smaller than the film thickness. In particular, we observe a minimum of the ablation threshold in a region where the film thickness is comparable to the absorption length. To the best of our knowledge, this behaviour previously predicted for thin metal films, has been unreported for all three regimes in case of transparent conductive oxides, yet. For industrial laser scribing processes, these results imply that the efficiency can be optimized by using a laser where the optical absorption length is close to the film thickness.

  8. Treatment of compounds and alloys in radiation hydrodynamics simulations of ablative laser loading.

    PubMed

    Swift, Damian C; Gammel, J Tinka; Clegg, Samuel M

    2004-05-01

    Different methods were compared for constructing models of the behavior of a prototype intermetallic compound, nickel aluminide, for use in radiation hydrodynamics simulations of shock wave generation by ablation induced by laser energy. The models included the equation of state, ionization, and radiation opacity. The methods of construction were evaluated by comparing the results of simulations of an ablatively generated shock wave in a sample of the alloy. The most accurate simulations were obtained using the "constant number density" mixture model to calculate the equation of state and opacity, and Thomas-Fermi ionization. This model is consistent with that found to be most accurate for simulations of ablatively shocked elements. PMID:15244945

  9. Imaging of laser-induced strain in biological tissue: pulsed holmium laser ablation of bovine cornea

    NASA Astrophysics Data System (ADS)

    Delacretaz, Guy P.; Walsh, Joseph T., Jr.; Beghuin, Didier

    1998-01-01

    Laser ablation of tissue can be accompanied by deleterious training. A polaroscopic technique was used to image induced strain. In a bovine cornea model, we demonstrate that strain induced by a cavitation bubble occurs over an area larger than the bubble. Further, although the bubble lifetime is only about 400 microseconds and the cornea tissue is strained greatly by the expanding and collapsing bubble, there is substantial strain for several milliseconds after the bubble collapse. The results indicate the utility of polaroscopic imaging as well as the magnitude and spatial extent of mechanical events at times long after the initiating mechanical insult.

  10. Patterned self-assembled monolayers of alkanethiols on copper nanomembranes by submerged laser ablation

    NASA Astrophysics Data System (ADS)

    Rhinow, Daniel; Hampp, Norbert A.

    2012-06-01

    Self-assembled monolayers (SAMs) of alkanethiols are major building blocks for nanotechnology. SAMs provide a functional interface between electrodes and biomolecules, which makes them attractive for biochip fabrication. Although gold has emerged as a standard, copper has several advantages, such as compatibility with semiconductors. However, as copper is easily oxidized in air, patterning SAMs on copper is a challenging task. In this work we demonstrate that submerged laser ablation (SLAB) is well-suited for this purpose, as thiols are exchanged in-situ, avoiding air exposition. Using different types of ?-substituted alkanethiols we show that alkanethiol SAMs on copper surfaces can be patterned using SLAB. The resulting patterns were analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Both methods indicate that the intense laser beam promotes the exchange of thiols at the copper surface. Furthermore, we present a procedure for the production of free-standing copper nanomembranes, oxidation-protected by alkanethiol SAMs. Incubation of copper-coated mica in alkanethiol solutions leads to SAM formation on both surfaces of the copper film due to intercalation of the organic molecules. Corrosion-protected copper nanomembranes were floated onto water, transferred to electron microscopy grids, and subsequently analyzed by electron energy loss spectroscopy (EELS).

  11. Understanding plume splitting of laser ablated plasma: A view from ion distribution dynamics

    SciTech Connect

    Wu, Jian; Li, Xingwen; Wei, Wenfu; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi 710049 (China)] [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi 710049 (China)

    2013-11-15

    Plume splitting in low-pressure ambient air was understood in view of ion distribution dynamics from the laser ablated Al plasma (1064 nm 0.57 J/mm{sup 2}) by combining fast photography and spatially resolved spectroscopy. In the beginning, the spectral lines were mainly from the Al III ion. Then, the Bragg peak in stopping power of the ambient gas to Al III could be the dominant reason for the enhanced emission from the fast moving part, and the recombination of Al III to Al I-II ions near the target surface was response to the radiations from the slow moving/stationary part. As the ambient gas pressure increased, stopping distances of the Al III decreased, and radiation from the air ions became pronounced. The laser shadowgraph image at 1100 Pa indicated that the shock wave front located between the fast moving and slow moving parts. Electron densities of the fast moving plasma, which peaked at the plasma front, were on the order of 10{sup 16} cm{sup ?3}, and the electron temperatures were 2–3 eV.

  12. Explosive detection using infrared laser spectroscopy

    Microsoft Academic Search

    J. Hildenbrand; J. Herbst; J. Wöllenstein; A. Lambrecht

    2009-01-01

    Stand-off and extractive explosive detection methods for short distances are investigated using mid-infrared laser spectroscopy. A quantum cascade laser (QCL) system for TATP-detection by open path absorption spectroscopy in the gas phase was developed. In laboratory measurements a detection limit of 5 ppm*m was achieved. For explosives with lower vapor pressure an extractive hollow fiber based measurement system was investigated.

  13. Infrared-laser spectroscopy, 1980-1983

    SciTech Connect

    McDowell, R.S.

    1983-01-01

    The review article used as a text for the Short Course on Infrared Laser Spectroscopy was completed in January 1980 and included only a few references after that date. There has ensued three years of progress, during which spectroscopy using tunable infrared lasers has become an increasingly used tool both for basic research and for analytical and industrial applications. The present paper, which follows closely the outline of the earlier review, updates the latter to early 1983. 238 references.

  14. A superconducting dipole magnet for laser spectroscopy

    E-print Network

    Wagenhauser, Kenneth Edward

    1990-01-01

    A SUPERCONDUCTING DIPOLE MAGNET FOR LASER SPECTROSCOPY A Thesis by KENNETH EDWARD WAGENHAUSER Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requhements for the degree of MASTER OF SCIENCE... May 1990 Major subject: Physics A SUPERCONDUCTING DIPOLE MAGNET FOR LASER SPECTROSCOPY A thesis by KENNETH EDWARD WAGENHAUSER Approved to as to style and content by: Hans A. Schuessler (Chair of Committee) David H. Russell (Member) Glenn A...

  15. The Mixed Processing Models Development Of Thermal Fracture And Laser Ablation On Glass Substrate

    NASA Astrophysics Data System (ADS)

    Huang, Kuo-Cheng; Wu, Wen-Hong; Tseng, Shih-Feng; Hwang, Chi-Hung

    2011-01-01

    As the industries of cell phone and LCD TV were vigorously flourishing and the manufacturing requirements for LCD glass substrate were getting higher, the thermal fracture cutting technology (TFCT) has progressively become the main technology for LCD glass substrate cutting. Due to using laser as the heat source, the TFCT has many advantages, such as uniform heating, small heat effect zone, and high cutting speed, smooth cutting surface and low residual stress, etc. Moreover, a general laser ablation processing or traditional diamond wheel cutting does not have the last two advantages. The article presents a mixed processing of glass substrate, which consists of TFCT and laser ablation mechanisms, and how to enhance the cutting speed with little ablation laser energy. In this study, a 10W Nd:YAG laser and a 40W CO2 laser are used as the heat source of TFCT and laser ablation processing, respectively. The result indicates that the speed of the mixed processing is more than twice the speed of TFCT. Furthermore, after the mixed processing, the residual stresses in the glass substrates are also smaller.

  16. Direct femtosecond laser ablation of copper with an optical vortex beam

    SciTech Connect

    Anoop, K. K.; Rubano, A.; Marrucci, L.; Bruzzese, R.; Amoruso, S., E-mail: amoruso@na.infn.it [Dipartimento di Fisica, Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); CNR-SPIN, UOS Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Fittipaldi, R.; Vecchione, A. [CNR-SPIN, UOS Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (Italy); Wang, X.; Paparo, D. [CNR-SPIN, UOS Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy)

    2014-09-21

    Laser surface structuring of copper is induced by laser ablation with a femtosecond optical vortex beam generated via spin-to-orbital conversion of the angular momentum of light by using a q-plate. The variation of the produced surface structures is studied as a function of the number of pulses, N, and laser fluence, F. After the first laser pulse (N=1), the irradiated surface presents an annular region characterized by a corrugated morphology made by a rather complex network of nanometer-scale ridges, wrinkles, pores, and cavities. Increasing the number of pulses (2ablated area is gradually decorated by nanoparticles produced during laser ablation. At large number of pulses (2001000) and a deep crater is formed. The nanostructure variation with the laser fluence, F, also evidences an interesting dependence, with a coarsening of the structure morphology as F increases. Our experimental findings demonstrate that direct femtosecond laser ablation with optical vortex beams produces interesting patterns not achievable by the more standard beams with a Gaussian intensity profile. They also suggest that appropriate tuning of the experimental conditions (F, N) can allow generating micro- and/or nano-structured surface for any specific application.

  17. Direct femtosecond laser ablation of copper with an optical vortex beam

    NASA Astrophysics Data System (ADS)

    Anoop, K. K.; Fittipaldi, R.; Rubano, A.; Wang, X.; Paparo, D.; Vecchione, A.; Marrucci, L.; Bruzzese, R.; Amoruso, S.

    2014-09-01

    Laser surface structuring of copper is induced by laser ablation with a femtosecond optical vortex beam generated via spin-to-orbital conversion of the angular momentum of light by using a q-plate. The variation of the produced surface structures is studied as a function of the number of pulses, N, and laser fluence, F. After the first laser pulse (N = 1), the irradiated surface presents an annular region characterized by a corrugated morphology made by a rather complex network of nanometer-scale ridges, wrinkles, pores, and cavities. Increasing the number of pulses (2 < N < 100), the surface texture progressively evolves towards larger structures, while the central, non-ablated area is gradually decorated by nanoparticles produced during laser ablation. At large number of pulses (200 < N < 1000), a micro-tip with a nanostructured surface forms in the center of the irradiated area, which eventually disappears at still larger number of pulses (N > 1000) and a deep crater is formed. The nanostructure variation with the laser fluence, F, also evidences an interesting dependence, with a coarsening of the structure morphology as F increases. Our experimental findings demonstrate that direct femtosecond laser ablation with optical vortex beams produces interesting patterns not achievable by the more standard beams with a Gaussian intensity profile. They also suggest that appropriate tuning of the experimental conditions (F, N) can allow generating micro- and/or nano-structured surface for any specific application.

  18. Comparison of the laser ablation process on Zn and Ti using pulsed digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Amer, E.; Gren, P.; Kaplan, A. F. H.; Sjödahl, M.; El Shaer, M.

    2010-05-01

    Pulsed digital holographic interferometry has been used to compare the laser ablation process of a Q-switched Nd-YAG laser pulse (wavelength 1064 nm, pulse duration 12 ns) on two different metals (Zn and Ti) under atmospheric air pressure. Digital holograms were recorded for different time delays using collimated laser light (532 nm) passed through the volume along the target. Numerical data of the integrated refractive index field were calculated and presented as phase maps. Intensity maps were calculated from the recorded digital holograms and are used to calculate the attenuation of the probing laser beam by the ablated plume. The different structures of the plume, namely streaks normal to the surface for Zn in contrast to absorbing regions for Ti, indicates that different mechanisms of laser ablation could happen for different metals for the same laser settings and surrounding gas. At a laser fluence of 5 J/cm 2, phase explosion appears to be the ablation mechanism in case of Zn, while for Ti normal vaporization seems to be the dominant mechanism.

  19. Two complementary ways of thin-metal-film patterning using laser beam interference and direct ablation

    NASA Astrophysics Data System (ADS)

    Indriši?nas, Simonas; Voisiat, Bogdan; Gedvilas, Mindaugas; Ra?iukaitis, Gediminas

    2013-09-01

    Interference of several identical laser beams allows for the fabrication of periodical structures over large areas. We present two complementary techniques for the patterning of thin films using the laser beam interference and direct ablation of material. The first one is based on precise control of the laser fluence relative to the ablation threshold of the film. Additional means for pattern management are provided by separate control of the intensity and phase of the interfering laser beams. Interference of four or six laser beams permits fabrication of periodical arrays of circular holes. Flexibility and sensitivity to the process parameters of the method beyond of simple hole arrays are shown for the thin Cr film ablation. Another versatile means for pattern generation in the films is the scanning of the periodic laser beam distribution over a workpiece in a sub-period area. By translation of the sample in small steps between laser shots, the structures with their shape independent of the interfering beam intensity distribution can be fabricated by overlapping the ablated holes. Slit- and cross-shaped periodical structures were fabricated using direct structuring with interfering nanosecond and femtosecond pulses. The thin-film structures fabricated by both techniques can be used as spectrally-selective elements for terahertz and infrared radiation.

  20. Optical feedback-induced light modulation for fiber-based laser ablation.

    PubMed

    Kang, Hyun Wook

    2014-11-01

    Optical fibers have been used as a minimally invasive tool in various medical fields. However, due to excessive heat accumulation, the distal end of a fiber often suffers from severe melting or devitrification, leading to the eventual fiber failure during laser treatment. In order to minimize thermal damage at the fiber tip, an optical feedback sensor was developed and tested ex vivo. Porcine kidney tissue was used to evaluate the feasibility of optical feedback in terms of signal activation, ablation performance, and light transmission. Testing various signal thresholds demonstrated that 3 V was relatively appropriate to trigger the feedback sensor and to prevent the fiber deterioration during kidney tissue ablation. Based upon the development of temporal signal signatures, full contact mode rapidly activated the optical feedback sensor possibly due to heat accumulation. Modulated light delivery induced by optical feedback diminished ablation efficiency by 30% in comparison with no feedback case. However, long-term transmission results validated that laser ablation assisted with optical feedback was able to almost consistently sustain light delivery to the tissue as well as ablation efficiency. Therefore, an optical feedback sensor can be a feasible tool to protect optical fiber tips by minimizing debris contamination and delaying thermal damage process and to ensure more efficient and safer laser-induced tissue ablation. PMID:24913423

  1. Atomic gallium laser spectroscopy with violet/blue diode lasers

    E-print Network

    Marago, O M; Gucciardi, P G; Arimondo, E

    2003-01-01

    We describe the operation of two GaN-based diode lasers for the laser spectroscopy of gallium at 403 nm and 417 nm. Their use in an external cavity configuration enabled the investigation of absorption spectroscopy in a gallium hollow cathode. We have analyzed the Doppler broadened profiles accounting for hyperfine and isotope structure and extracting both the temperature and densities of the neutral atomic sample produced in the glow discharge. We have also built a setup to produce a thermal atomic beam of gallium. Using the GaN-based diode lasers we have studied the laser induced fluorescence and hyperfine resolved spectra of gallium.

  2. Plasma Based X-ray Lasers Used For Opacity and Ablation Rate Measurements

    SciTech Connect

    Tallents, G. J.; Edwards, M. H.; Mistry, P.; Whittaker, D. S.; Booth, N.; Huang, H.; Pert, G. J. [Department of Physics, University of York, York YO10 5D (United Kingdom); Rus, B.; Mocek, T.; Kozlova, M. [PALS Centre, 18221 Prague 8 (Czech Republic); Lewis, C. L. S.; McKenna, C.; Delseriey, A. [Department of Pure and Applied Physics, Queen's University Belfast, Belfast BT7 1NN (United Kingdom); Notley, M.; Neely, D. [Central Laser Facility, Rutherford Appleton Laboratory, Chilton Didcot OX11 0QX (United Kingdom)

    2006-04-07

    Utilizing thin targets, opacities of iron have been measured using x-ray lasers of photon energy 89 eV created by pumping with the VULCAN laser. The thin targets comprise a plastic substrate, a 50 nm thick iron layer and an overlay of 100 nm CH and are separately heated by spot focus laser pulses. We have demonstrated that X-ray laser brightness is sufficient to overcome the self-emission of hot plasma so that useful opacity measurements can be made. The transmission through the targets agrees generally with the calculated transmission from a fluid code simulation coupled to the TOPS plasma opacity data. The ablation of aluminum foil with a thin (50 nm) iron coating was also observed using a neon-like zinc x-ray laser of photon energy 58 eV at the PALS centre. The x-ray laser was used to probe sample targets as they were heated by a separate laser beam of 10 J, focused to a 100 micron diameter spot. A simple calculation of the rate of ablation of the iron gives x-ray laser transmission through the targets in agreement with experiment. We suggest that x-ray laser probing can be a useful diagnostic of ablation rates in laser-plasmas.

  3. Using a Fast-Scanning Electrical Nanoparticle Sizer to Characterize Nanoparticles from Laser Ablation

    SciTech Connect

    Chen, Da-Ren [ORNL; Cheng, Mengdawn [ORNL

    2007-01-01

    A Fast-Scanning Electrical Nanoparticle Sizer (FSENS) consisting of a Po 210 bipolar charger, a Nano-DMA, and an aerosol electrometer was used to characterize nanoparticles generated by laser ablating the surfaces of cement, chromium-embedded cement, stainless steel, and alumina samples. Different from previous studies, bimodal size distributions, with the nucleation mode having a geometric mean diameter ranging from 5.7-6.6 nm and a geometric standard deviation varying from 1.225-1.379, were observed for all the experimental runs. The curve fitting shows that the bimodal size distribution produced in the laser ablation can be best fitted by a lognormal distribution for the nucleation mode and a Rosin-Rammler distribution for the coagulation mode. At steady state the geometric mean diameter of the coagulation mode was affected by the laser wavelength and target material, but was less influenced by laser energy for a given wavelength. The total particle number concentrations of the two modes appear to be parabolic with respect to the laser fluence. At a given fluence, the stainless-steel sample produced the highest particle number concentration with 532- and 1064-nm lasers; the alumina sample produced the lowest particle number concentration with 266- and 1064-nm lasers. The chromium-embedded cement sample produced fewer particles with 532- and 1064 nm lasers than the pure cement sample. This study also demonstrated that FSENS can provide snapshots of the nanoparticle dynamics during laser ablation in cases of low laser fluence.

  4. Formation of high mass carbon cluster ions from laser ablation of polymers and thin carbon films

    NASA Astrophysics Data System (ADS)

    Creasy, William R.; Brenna, J. T.

    1990-02-01

    Three materials were studied by laser ablation/Fourier transform mass spectrometry, using 266 nm laser radiation: a copolymer of ethylene and tetrafluoroethylene (ETFE), polyphenylene sulfide (PPS), and a diamond-like carbon film (DLC). In each case, positive ion mass spectra exhibit primarily even-numbered, high mass carbon clusters (``fullerenes'') of the type previously reported for graphite ablation. In the case of ETFE, a large C+60 peak (``buckminsterfullerene'') was observed. The polymer spectra showed a strong dependence on the number of laser pulses on one spot and the laser power density. For ETFE, the fullerene ion relative intensity first increases and then decreases as a function of the number of laser pulses. For the DLC film, fullerenes are observed with a single laser pulse on a fresh spot of the sample. The results are interpreted in terms of a gas phase growth model for the fullerene ion formation.

  5. Trace level determination of lead in solid samples by UV laser ablation and laser-enhanced ionization detection.

    PubMed

    Gravel, Jean-François; Nobert, Philippe; Gravel, Jean-François Y; Boudreau, Denis

    2003-03-15

    Laser-enhanced ionization was investigated as a detection technique for trace elemental analysis of solid samples by laser ablation. Laser ablation of aluminum samples was performed in an ablation cell, and the ablated material was carried by a flow of gas to a miniature LEI flame where Pb was detected. This decoupling of ablation cell and detector allowed the independent optimization of vaporization and detection processes. We have investigated the different excitation schemes for Pb and uncovered five new LEI-active transitions in the visible range. We have demonstrated that the use of an argon-oxygen/acetylene flame sheathed with argon resulted in the elimination of background interference from the two-photon ionization of nitric oxide. We have shown that the use of helium as a carrier gas results in a higher ablation yield and lower pulse-to-pulse variations in LEI signal and in better analytical figures of merit. We have characterized the performance of the technique in terms of detection limits and dynamic range, and we have obtained a detection limit of 60 ng/g for the determination of Pb in high purity aluminum. PMID:12659208

  6. A novel approach for high selective micro-sampling of organic painting materials by Er:YAG laser ablation

    Microsoft Academic Search

    Maria Perla Colombini; Alessia Andreotti; Giancarlo Lanterna; Maria Rizzi

    2003-01-01

    A new approach for sampling micro-amounts of mainly organic materials from thin layers of a painting is described. A pulsed Er:YAG laser system operating at 2.94 ?m was used for collecting ablate materials. The experimental ablation conditions optimised on reference paint layer samples resulted in using laser energy lower than 20 mJ at 15 pulses\\/s (pps) assisted by water\\/ethanol mixtures. The ablate materials

  7. The effect of film properties and laser processing parameters on the laser ablation of molybdenum thin films

    NASA Astrophysics Data System (ADS)

    Schneller, Eric; Rodrigues, Rafael; Dhere, Neelkanth G.; Kar, Aravinda

    2014-10-01

    Molybdenum is commonly used as the electrical back contact for Cu(In,Ga)(Se,S)2 thin-film solar cells. In order to create a monolithically interconnected device, scribing of the molybdenum layer is required. This scribe, known as the P1 scribe, is commonly carried out through laser processing. Optimization of this laser scribing has been carried out using a 532nm pulsed Nd:YAG laser. It was found that two specific regimes of processing resulted in defect free scribes. These regimes are low fluency and high pulse overlap, and high fluency and low pulse overlap. Film properties, including the microstructure, surface oxidation, and internal stress, were studied to understand their effect on the laser ablation process. It was observed that a thin layer of oxidation resulted in significant heat affected zone during the laser ablation process. A discussion of the optimal film properties and laser processing parameters is presented.

  8. Resonant holographic interferometry measurements of laser ablation plumes in vacuum, gas, and plasma environments

    Microsoft Academic Search

    R. A. Lindley; R. M. Gilgenbach; C. H. Ching; J. S. Lash; G. L. Doll

    1994-01-01

    Resonant holographic interferometry and dye-laser-resonance-absorption photography have been utilized to investigate the expansion of the laser ablation plumes produced by a KrF excimer laser beam (248 nm) focused onto an aluminum target (≊0.1 cm2, 2–6 J\\/cm2). Plume expansion was studied in vacuum and in background argon gas pressures of 14 mTorr, 52 mTorr, 210 mTorr, 1 Torr, and 35 Torr.

  9. Resonant holographic interferometry measurements of laser ablation plumes in vacuum, gas, and plasma environments

    Microsoft Academic Search

    R. A. Lindley; R. M. Gilgenbach; C. H. Ching; J. S. Lash; G. L. Doll

    1994-01-01

    Resonant holographic interferometry and dye-laser-resonance-absorption photography have been utilized to investigate the expansion of the laser ablation plumes produced by a KrF excimer laser beam (248 nm) focused onto an aluminum target (about = 0.1 sq cm, 2 - 6 J\\/sq cm). Plume expansion was studied in vacuum and in background argon gas pressures of 14 m Torr, 52 m

  10. Comparison between laser and electrical ablation of ventricle in dogs: Hemodynamic, pathologic and electrocardiographic observations

    Microsoft Academic Search

    Wu Tian-gen; Lu Zai-ying

    1992-01-01

    Summary  To characterize and compare the pathologic, hemodynamic and electrocardiographic changes of both transeatheter laser and electrical\\u000a energy on ventricle, 33 subendocardial myocardium lesions were induced at energy 60, 120 and 240 Joules by either transcatheter\\u000a laser irradiation or electrical shock in 7 anesthetized dogs. The following results were observed: 1) Both laser and electrical\\u000a ablation on myocardium created nonhomogeneous myocardium

  11. Multielement analysis of compost by laser ablation-inductively coupled plasma mass spectrometry

    Microsoft Academic Search

    María S. Jiménez; María T. Gómez; Juan R. Castillo

    2007-01-01

    Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been applied to multi-element determination in compost samples. Since compost is a heterogeneous mixture of organic and inorganic materials, the influence of sample heterogeneity on the accuracy and precision of analysis was investigated. Several parameters related to the following were studied: laser (energy, laser-beam diameter, preablation. rastering speed, carrier-gas flow rate),

  12. Properties of conductive PEDOT:PSS films deposited by resonant infrared laser ablation

    Microsoft Academic Search

    S. L. Johnson; H. K. Park; R. F. Haglund Jr.

    2007-01-01

    Thin films of the conducting polymer poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) were deposited by resonant infrared laser ablation. The PEDOT:PSS was frozen in various matrix solutions and deposited using a tunable, mid-infrared free-electron laser (FEL). The films so produced exhibited morphologies and conductivities that were highly dependent on the solvent matrix and laser irradiation wavelength used. When deposited from a native solution (5%

  13. Tissue ablation by a free-electron laser tuned to the amide II band

    Microsoft Academic Search

    Glenn Edwards; Regan Logan; Michael Copeland; Lou Reinisch; Jeffrey Davidson; Bruce Johnson; Robert Maciunas; Marcus Mendenhall; Robert Ossoff; Jerri Tribble; Jay Werkhaven; Denis O'Day

    1994-01-01

    EFFORTS to ablate soft tissue with conventional lasers have been limited by collateral damage and by concern over potential photochemical effects1 5. Motivated by the thermal-confinement model6, past infrared investigations targeted the OH-stretch mode of water with fast pulses from lasers emitting near 3,000 nm (refs 1, 7 9). What does a free-electron laser offer for the investigation of tissue

  14. Enhancement of muonium emission rate from silica aerogel with a laser ablated surface

    E-print Network

    Beer, G A; Hirota, S; Ishida, K; Iwasaki, M; Kanda, S; Kawai, H; Kawamura, N; Kitamura, R; Lee, S; Marshall, W Lee G M; Mibe, T; Miyake, Y; Okada, S; Olchanski, K; Olin, A; Oishi, Y; Onishi, H; Otani, M; Saito, N; Shimomura, K; Strasser, P; Tabata, M; Tomono, D; Ueno, K; Yokoyama, K; Won, E

    2014-01-01

    Emission of muonium ($\\mu^+e^-$) atoms from a laser-processed aerogel surface into vacuum was studied for the first time. Laser ablation was used to create hole-like regions with diameter of about 270$~\\mu$m in a triangular pattern with hole separation in the range of 300--500$~\\mu$m. The emission probability for the laser-processed aerogel sample is at least eight times higher than for a uniform one.

  15. Hyperthermal Pulsed-Laser Ablation Beams for Film Deposition and Surface Microstructural Engineering

    SciTech Connect

    Lowndes, D.H.

    1999-11-08

    This paper presents an overview of pulsed-laser ablation for film deposition and surface microstructure formation. By changing the ambient gas pressure from high vacuum to several Torr (several hundred Pa) and by selecting the pulsed-laser wavelength, the kinetic energy of ablated atoms/ions can be varied from several hundred eV down to {approximately}0.1 eV and films ranging from superhard to nanocrystalline may be deposited. Furthermore, cumulative (multi-pulse) irradiation of a semiconductor surface (e.g. silicon) in an oxidizing gas (0{sub 2}, SF{sub 6}) et atmospheric pressure can produce dense, self-organized arrays of high-aspect-ratio microcolumns or microcones. Thus, a wide range of materials synthesis and processing opportunities result from the hyperthermal flux and reactive growth conditions provided by pulsed-laser ablation.

  16. Fabrication of a super-hydrophobic surface on metal using laser ablation and electrodeposition

    NASA Astrophysics Data System (ADS)

    Kwon, Min Ho; Shin, Hong Shik; Chu, Chong Nam

    2014-01-01

    In this research, the fabrication process of a super-hydrophobic metallic surface using laser ablation and electrodeposition was investigated. Re-entrant structure and surface roughness play an important role in forming a super-hydrophobic surface on intrinsically hydrophilic material. A micro pillar array with a re-entrant structure of copper on stainless steel was fabricated through a sequential process of laser ablation, insulating, mechanical polishing and electrodeposition. Spacing of the micro pillars in the array played a major role in the structure hydrophobicity that was confirmed by measuring the water contact angle. Surface morphology changed relative to the parameters of the laser ablation process and electrodeposition process. Under a gradual increase in current density during the electrodeposition process, surface morphology roughness was maximized for fabricating a super-hydrophobic surface. Finally, the super-hydrophobic surface was successfully fabricated on metal.

  17. Production of ion and electron streams by pulsed-laser ablation of Ta and Cu

    NASA Astrophysics Data System (ADS)

    Margarone, D.; Torrisi, L.; Picciotto, A.; Caridi, F.; Gammino, S.

    2005-10-01

    A Nd:YAG laser with 10(9) W/cm(2) pulse intensity, operating at 532 nm wavelength, is used to ablate Ta and Cu targets placed in vacuum. The ablation process generates a plasma in front of the target surface, which expands along the normal to target surface. The ion and electron emissions from the plasma were measured by Faraday cups placed at different angles with respect to the normal to target surface. In the range of laser intensities from 10(7) to 10(9) W/cm(2) , the fast electron yield is lower than the ion yield and it increases at higher laser intensities. The ablation threshold, the emission yield, the ion and electron average energies and the plasma ion and electron temperatures were measured for ion and fast electron streams.

  18. Synthetic characteristics of large carbon cluster ions by laser ablation of polymers in vacuum

    NASA Astrophysics Data System (ADS)

    Shibagaki, K.; Takada, N.; Sasaki, K.; Kadota, K.

    2003-01-01

    The synthetic characteristics of large carbon cluster ions by laser ablation of polymers in vacuum were investigated. Time-of-flight mass spectrometry was used for analyzing the masses of ionic species produced by laser ablation. We found that large carbon cluster ions Cn+ with n up to 400 were synthesized in vacuum when copolymer of ethylene and tetrafluoroethylene, polyvinyliden fluoride, and chlorotrifluoroethylene were employed as the target material. Since the synthesis of large cluster ions in vacuum is a surprising phenomenon, we examined the synthesis efficiency in various experimental conditions. By comparing mass spectra obtained from various polymers containing hydrogen and/or halogen atoms, the existence of both hydrogen and halogen atoms in polymers do not directly contribute to enhance the synthesis efficiency of large carbon clusters. In addition, microscopic observations of surface morphologies of laser-ablated polymers revealed that the clustering reactions in eroded craters had little correlation with the synthesis efficiency of large carbon clusters.

  19. A scattered-light-based system for the probe beam monitoring of laser ablation dynamic

    NASA Astrophysics Data System (ADS)

    de Souza, Hanriete P.; Munin, Egberto; Alves, Leandro P.; Redigolo, Marcela L.; Pacheco, Marcos Tadeu T.

    2004-07-01

    In this work we employ a novel probe-beam technique to access the plume dynamics in the laser ablation process. A helium-neon laser in the scattered-beam mode was used to probe the plume. The sample used was a chicken myocardium tissue. The scattered probe light was collected by a 600 mm optical fiber and sent to a ­ m spectrometer. After finding an adequate acquisition time window, the scattered He-Ne laser light was analyzed for several delay times. The plume luminescence was also collected. While no defined spectral lines could be observed for a 100 ?s acquisition time window, a large number of emission lines could be analyzed for the 5 ms gate, the optimum gate window. Our results also show that the ejected material starts to be registered by the spectrometer at about 40 ?s after the ablation pulse has been fired. The measurement of the relative atomic composition by means of the laser ablation and the analysis of the ablation plume dynamics were performed. The results pointed out the presence of many elements including sodium, hydrogen and others. Understanding the mechanisms involved in tissue ablation allows reduced damage and better results depending on the application goals.

  20. Laser ablation and deposition of titanium dioxide with ultrashort pulses at 527 nm

    NASA Astrophysics Data System (ADS)

    Pallotti, D. K.; Ni, X.; Fittipaldi, R.; Wang, X.; Lettieri, S.; Vecchione, A.; Amoruso, S.

    2015-06-01

    We report an experimental analysis on laser ablation and deposition of TiO2 with ?300-fs, 527-nm ultrashort laser pulses. We particularly address the following: (1) the dependence of the deposition rate on the laser fluence, in high-vacuum conditions; (2) the effect of an oxygen background gas pressure on the expansion of the ablated species and on the deposition rate. Two different regimes are observed for the dependence of the deposition rate in high vacuum: The first one governed by two-photon absorption occurring close to the ablation threshold is, then, followed by the second, thermal dependence at larger fluences. The propagation of the atomic and nanoparticulate plumes produced in ultrashort laser ablation are influenced in a quite different way by the background gas pressure, which eventually reflects on the variation of the deposition rate with pressure. Moreover, it is observed that the ablated material is predominantly composed of nanoparticles (?70 %), similar to what was reported before in the case of elemental metallic targets. Finally, plume deposition results in the formation of nanoparticle-assembled films with a variation of the characteristics morphology with the background gas pressure.

  1. Glass microprocessing by laser-induced plasma-assisted ablation: fundamental to industrial applications

    NASA Astrophysics Data System (ADS)

    Sugioka, Koji; Midorikawa, Katsumi; Yamaoka, Hiroshi; Gomi, Yutaka; Otsuki, Masayoshi; Hong, Ming Hui; Wu, Dong Jiang; Wong, Lai Lee; Chong, Tow Chong

    2004-07-01

    Laser-induced plasma-assisted ablation (LIPAA), in which a single conventional pulsed laser of small size is employed (typically 2nd harmonic of Nd:YAG laser), enables to process transparent materials like glass with micron order spatial resolution, high speed and low cost. In this process, a laser beam is first directed to a glass substrate placed in vacuum or air. The laser beam passes through the substrate since the wavelength of laser beam must have no absorption by the substrate for the LIPAA process. The transmitted laser beam is absorbed by a solid target (typically metal) located behind the substrate. The target is then ablated, resulting in plasma generation. Due to the interaction of the laser beam and the laser-induced plasma, significant ablation takes place at the rear surface of substrate. This process demonstrates surface microstructuring, crack-free marking, color marking, painting and selective metallization of glass. Based on these achievements, we have developed a prototype of workstation of LIPAA microfabrication system which is now commercially available. The discussion includes mechanism and practical applications in industry of LIPAA process.

  2. Mission feasibility analysis on deflecting Earth-crossing objects using a power limited laser ablating spacecraft

    NASA Astrophysics Data System (ADS)

    Song, Young-Joo; Park, Sang-Young; Choi, Kyu-Hong

    2010-01-01

    This paper analyzes several mission capabilities to deflect Earth-crossing objects (ECOs) using a conceptual future spacecraft with a power limited laser ablating tool. A constrained optimization problem is formulated based on nonlinear programming with a three-dimensional patched conic method. System dynamics are also established, considering the target ECO’s orbit as being continuously perturbed by limited laser power. The required optimal operating duration and operating angle history of the laser ablating tool are computed for various types of ECOs to avoid an Earth impact. The available final warning time is also determined with a given limited laser power. As a result, detailed laser operating behaviors are presented and discussed, which include characteristics of operating duration and angle variation histories in relation to the operation’s start time and target object’s properties. The calculated durations of the optimal laser operation are also compared to those estimated with first-order approximations previous studies. It is discovered that the duration of the laser operation estimated with first-order approximations could result in up to about 50% error if the operation is started at the final warning time. The laser operation should be started as early as possible because an early start requires a short operating duration with a small operating angle variation. The mission feasibility demonstrated in the present study will give various insights into preparing future deflection missions using power limited spacecraft with a laser ablation tool.

  3. Orbit Modification of Earth-Crossing Asteroids/Comets Using Rendezvous Spacecraft and Laser Ablation

    NASA Technical Reports Server (NTRS)

    Park, Sang-Young; Mazanek, Daniel D.

    2005-01-01

    This report describes the approach and results of an end-to-end simulation to deflect a long-period comet (LPC) by using a rapid rendezvous spacecraft and laser ablation system. The laser energy required for providing sufficient deflection DELTA V and an analysis of possible intercept/rendezvous spacecraft trajectories are studied in this analysis. These problems minimize a weighted sum of the flight time and required propellant by using an advanced propulsion system. The optimal thrust-vector history and propellant mass to use are found in order to transfer a spacecraft from the Earth to a targeted celestial object. One goal of this analysis is to formulate an optimization problem for intercept/rendezvous spacecraft trajectories. One approach to alter the trajectory of the object in a highly controlled manner is to use pulsed laser ablative propulsion. A sufficiently intense laser pulse ablates the surface of a near-Earth object (NEO) by causing plasma blowoff. The momentum change from a single laser pulse is very small. However, the cumulative effect is very effective because the laser can interact with the object over long periods of time. The laser ablation technique can overcome the mass penalties associated with other nondisruptive approaches because no propellant is required to generate the DELTA V (the material of the celestial object is the propellant source). Additionally, laser ablation is effective against a wide range of surface materials and does not require any landing or physical attachment to the object. For diverting distant asteroids and comets, the power and optical requirements of a laser ablation system on or near the Earth may be too extreme to contemplate in the next few decades. A hybrid solution would be for a spacecraft to carry a laser as a payload to a particular celestial body. The spacecraft would require an advanced propulsion system capable of rapid rendezvous with the object and an extremely powerful electrical generator, which is likely needed for the propulsion system as well. The spacecraft would station-keep with the object at a small standoff distance while the laser ablation is performed.

  4. Isotope ratio analysis on micron-sized particles in complex matrices by Laser Ablation-Absorption Ratio Spectrometry

    Microsoft Academic Search

    Bruce A. Bushaw; Norman C. Anheier

    2009-01-01

    Laser ablation has been combined with dual tunable diode laser absorption spectrometry to measure 152Gd:160Gd isotope ratios in micron-size particles. The diode lasers are tuned to specific isotopes in two different atomic transitions at 405.9nm (152Gd) and 413.4nm (160Gd) and directed collinearly through the laser ablation plume, separated on a diffraction grating, and detected with photodiodes to monitor transient absorption

  5. Bacterial infections following non-ablative fractional laser treatment: a case series and discussion.

    PubMed

    Xu, Lisa Y; Kilmer, Suzanne L; Ross, E Victor; Avram, Mathew M

    2015-02-01

    Non-ablative fractional laser procedures have become increasingly popular since their introduction in 2004. The fractional 1,927?nm thulium laser is a non-ablative device that penetrates up to 300??m in the skin and the 1,550?nm erbium:glass laser penetrates up to 1,400??m. These procedures are considered minimally invasive with a high safety profile; therefore, infectious complications are exceedingly rare. However, we report five recent cases of bacterial infection with both gram-positive and gram-negative organisms following treatment with the fractional 1550/1927?nm laser approximately 1 day to 1 week post-procedure. One patient had a rapidly progressing pustular eruption with symptoms of sepsis. These patients were seen immediately, cultures were obtained and empiric antibiotic therapy was initiated. They recovered without long-term complications. Rapid-onset bacterial infections following non-ablative laser resurfacing with the 1550/1927?nm laser have not been previously reported in the literature. The infections can progress quickly and lead to serious sequelae, including systemic illness and severe scarring, if not identified and appropriately treated. We present these cases to highlight the importance of close surveillance and when appropriate, rapid intervention, following non-ablative fractional procedures, especially when patients present with atypical symptoms and signs. PMID:25586939

  6. Treatment of Barrett's esophagus by endoscopic laser ablation and antireflux surgery.

    PubMed Central

    Salo, J A; Salminen, J T; Kiviluoto, T A; Nemlander, A T; Rämö, O J; Färkkilä, M A; Kivilaakso, E O; Mattila, S P

    1998-01-01

    OBJECTIVE: The regeneration of intestinal metaplasia by squamous epithelium in 17 patients with Barrett's esophagus after endoscopic laser ablation in a reflux-free environment after successful antireflux surgery was prospectively examined. METHODS: All patients had antireflux surgery, and healing of reflux was verified at postoperative endoscopy and 24-hour esophageal pH monitoring. Thereafter, in 11 patients, the whole Barrett's epithelium was ablated using endoscopic Nd-YAG laser energy in 1 to 8 sessions (mean, 4). The needed energy was 965 to 11,173 joules (mean 4709), or about 1000 joules per centimeter of Barrett's esophagus. Six patients had no laser ablation but were treated by antireflux surgery and served as a control group. RESULTS: In all laser-treated patients, the regenerated epithelium was histologically of squamous type in the tubular esophagus, but two patients still had intestinal metaplasia in the gastric cardia. In controls, the length of Barrett's esophagus and intestinal metaplasia remained unchanged. The length of follow-up was 26 months after the last laser session and 21 months in the control group. CONCLUSIONS: The regenerated esophageal epithelium arising after laser ablation in reflux-free environment surgery is of squamous type. This treatment may have a role in preventing the development of esophageal adenocarcinoma arising in Barrett's esophagus. Images Figure 2. PMID:9445108

  7. Glass particles produced by laser ablation for ICP-MS measurements.

    PubMed

    Gonzalez, Jhanis J; Liu, Chunyi; Wen, Sy-Bor; Mao, Xianglei; Russo, Richard E

    2007-09-30

    Pulsed laser ablation (266nm) was used to generate glass particles from two sets of standard reference materials using femtosecond (150fs) and nanosecond (4ns) laser pulses with identical fluences of 50Jcm(-2). Scanning electron microscopy (SEM) images of the collected particles revealed that there are more and larger agglomerations of particles produced by nanosecond laser ablation. In contrast to the earlier findings for metal alloy samples, no correlation between the concentration of major elements and the median particle size was found. When the current data on glass were compared with the metal alloy data, there were clear differences in terms of particle size, crater depth, heat affected zone, and ICP-MS response. For example, glass particles were larger than metal alloy particles, the craters in glass were less deep than craters in metal alloys, and damage to the sample was less pronounced in glass compared to metal alloy samples. The femtosecond laser generated more intense ICP-MS signals compared to nanosecond laser ablation for both types of samples, although glass sample behavior was more similar between ns- and fs-laser ablation than for metal alloys. PMID:19073073

  8. Femtosecond laser ablation inductively coupled plasma mass spectrometry: fundamentals and capabilities for depth profiling analysis.

    PubMed

    Pisonero, Jorge; Günther, Detlef

    2008-01-01

    Laser ablation coupled to inductively coupled plasma mass spectrometry has become a versatile and powerful analytical method for direct solid analysis. The applicability has been demonstrated on a wide variety of samples, where major, minor, and trace element concentrations or isotope ratio determinations have been of interest. The pros and cons of UV-nsec laser ablation have been studied in detail, and indicate that aerosol generation, aerosol transport, and aerosol excitation-ionization within the ICP contribute to fractionation effects, which prevent this method from a more universal application to all matrices and all elements. Recent progresses in IR-fs and UV-fs laser ablation coupled to ICP-MS have been reported, which increase the inter-matrix and multi-element quantification capabilities of this method. These fundamental improvements in LA-ICP-MS are of significant importance for entering new applications in material science and related research fields. In particular, because coatings (conducting and non-conducting) consist of single or multilayers of various elemental composition and of different thickness (nm-mm range), significant progress in the field of depth profiling with fs-laser ablation can be expected. Therefore, in-depth profile analysis of polymers, semiconductors, and metal sample investigations, using ultra-fast laser ablation for sampling and the currently achievable figures of merit, are discussed. In this review manuscript, the enhanced capabilities of fs-LA-ICP-MS for direct solid sampling are highlighted, and it is discussed about current methods used for quantitative analysis and depth profiling, the ablation process of UV-ns and UV-fs, the influence of the laser beam profile, aerosol structure and transport efficiency, as well as the influence of the ICP-MS (e.g., vaporization and ionization efficiency in the plasma, and type of mass analyzer). PMID:18636536

  9. Argon laser ablation of malignant ventricular tachycardia associated with coronary artery disease.

    PubMed

    Saksena, S; Gielchinsky, I; Tullo, N G

    1989-12-01

    The long-term clinical efficacy and safety of intraoperative mapping-guided argon laser ablation alone or in conjunction with standard surgical methods were assessed in 20 consecutive patients with refractory sustained ventricular tachycardia (VT) or ventricular fibrillation. A 15-W argon ion gas laser was used and pulsed laser energy was delivered through a fiberoptic catheter delivery system. Pre- and intraoperative mapping was used to localize the arrhythmogenic tissue. Postoperative clinical, ambulatory electrocardiographic and electrophysiologic evaluations were performed before discharge and at 1 year of follow-up. Thirty-eight VT morphologies were mapped and ablated with laser energy alone (82%), combined laser ablation and mechanical resection (13%) or mechanical resection alone (5%). Concomitant coronary artery bypass surgery was performed in 15 patients and in 1 patient it was performed with mitral value replacement. Postoperative 30-day mortality was 5%. One patient (5%) required postoperative antiarrhythmic drug therapy, and all survivors had suppression of inducible sustained VT at discharge. Mean left ventricular ejection fraction increased from 34 +/- 12% preoperatively to 41 +/- 13% postoperatively (p = 0.001). Efficacy rates for ablation of VT sites associated with anterior myocardial infarction and inferior or posterior myocardial infarction were comparable (100 vs 96%, respectively, p greater than 0.2). At 1-year follow-up no sudden deaths had occurred and total survival rate was 90%. Intraoperative pulsed argon laser ablation alone or in conjunction with standard surgical techniques improves the efficacy of surgical ablation procedures for VT or ventricular fibrillation and reduces the need for additional postoperative antiarrhythmic drug or device therapy. PMID:2589195

  10. Thermal model of nanosecond pulsed laser ablation: Analysis of energy and mass transfer

    SciTech Connect

    Gusarov, Andrey V.; Smurov, Igor [Baikov Institute of Metallurgy, Russian Academy of Sciences, Leninsky Prospect 49, 119991 Moscow (Russian Federation); Ecole Nationale d'Ingenieurs de Saint Etienne, 58 rue Jean Parot, F-42023 Saint Etienne Cedex 2 (France)

    2005-01-01

    A thermal model of nanosecond laser ablation considering kinetics of surface evaporation is proposed. Equations concerning heat transfer in the target and associated gas dynamics are coupled by mass and energy balances at the surface and Knudsen layer conditions. Rigorous analysis of gas-dynamics related to condensation at the target surface is introduced in this model. Laser energy absorbed by the target is partly spent for evaporation and partly dissipated in the target by thermal conduction. The sum of thermal and kinetic energies of the gas phase is, usually, less than the energy of evaporation. The fraction of energy lost for target heating increases with decrease in laser fluence and attains 100% at the ablation threshold. The dependence of ablated depth on fluence is, thus, determined by energy partition between the solid and gas phases. The gas-dynamic flow accompanying ablation consists of a layer of compressed high-temperature vapor adjacent to the target that expands and pushes the ambient gas from the surface to generate a strong shock wave. Ablation of Al and Au by laser with 193 nm wavelength, 12 ns full width at half maximum (FWHM) pulses, and 5.3 J/cm{sup 2} incident fluence and that of Au by laser with 266 nm wavelength, 6 ns FWHM, and 3.5 J/cm{sup 2} incident fluence is analyzed utilizing the present thermal model. It is concluded that optical breakdown does not occur at the considered conditions. The present model can be applied when the target surface temperature is less than the critical temperature. In case of nanosecond laser ablation of metals this, normally, restricts the value of absorbed fluence by the maximum of several J/cm{sup 2}.

  11. Noninvasive characterization of fractional photothermolysis induced by ablative and non-ablative lasers with optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Tsai, M. T.; Yang, C. H.; Shen, S. C.; Chang, F. Y.; Lee, J. D.; Yi, J. Y.; Fan, C. H.

    2013-07-01

    In this study, an optical coherence tomography (OCT) system is implemented for the noninvasive characterization of photothermolysis in human skin induced by ablative fractional lasers (AFLs) and non-ablative fractional lasers (NAFLs). With OCT imaging, microthermal zones (MTZs) induced by fractional lasers can be noninvasively visualized, and the size of induced MTZs can be quantitatively evaluated. According to the OCT results, the center region of the induced MTZ corresponds to weaker backscattered intensity after the AFL exposure as a result of tissue volatilization by photon energy. In contrast, after the NAFL exposure, the skin tissue is damaged and coagulated but not volatilized, which causes the backscattered intensity of the induced MTZ enhanced in the OCT image. To further identify the photothermolysis induced by AFLs or NAFLs, the backscattered intensities of MTZs are compared with those of the untreated tissue from the OCT results. The statistical result shows a clear difference in scattering properties of photothermolysis induced by AFLs and NAFLs. Finally, the induced photodamage at various depths can also be quantitatively evaluated, enabling an investigation of the relationship between the photodamage and the depth.

  12. Investigation of the spatial and temporal distribution of plasma excited species produced in laser ablation-glow discharge

    NASA Astrophysics Data System (ADS)

    Valledor, Rebeca; Tarik, Mohamed; Pisonero, Jorge; Bordel, Nerea; Günther, Detlef

    2014-10-01

    Laser Ablation and Glow Discharge (LAGD) plasmas have been coupled and optical emission measurements have been performed in order to study the spatial and temporal distribution of LA and GD species and hence to get further insights into the interaction between them. The relative delay between the laser event and the emission measurement along the GD pulse has been found as a crucial parameter. In addition, no post excitation of the ablated material has been observed when laser ablation takes place during GD prepeak or plateau. In contrast, emission enhancements (e.g. Al I lines at ~ 877 nm presented an enhancement of up to 4 times in the LAGD plasma) were obtained during the afterglow or late plateau, when firing the laser at delays close (< 100 ?s) to GD pulse termination. Penning ionization of the ablated material within the GD afterglow, followed by recombination processes, seems to account for the emission enhancements obtained when combining laser ablation and glow discharge.

  13. Comparison of plasma temperature and electron density on nanosecond laser ablation of Cu and nano-Cu

    NASA Astrophysics Data System (ADS)

    Chen, Anmin; Jiang, Yuanfei; Wang, Tingfeng; Shao, Junfeng; Jin, Mingxing

    2015-03-01

    Laser-induced breakdown spectroscopy is performed through the collection of spectra by spectral detection equipment at different delay times and distances from targets composed of Cu and nano-Cu, which are ablated using a Nd:YAG laser (532 nm, 10 ns, 10 Hz) in our experiments. The measured wavelength range is from 475 nm to 525 nm. Using the local thermodynamic equilibrium model, we analyze the characteristics of the plasma temperature and the electron number density for different distances between the target surface and the lens. The results show that when compared with the nano-Cu plasma case, the temperature of the Cu plasma is higher, while its electron number density is lower.

  14. Dense strongly coupled plasma in double laser pulse ablation of lithium: Experiment and simulation

    SciTech Connect

    Kumar, Ajai; Sivakumaran, V.; Ganesh, R.; Joshi, H. C. [Institute for Plasma Research, Bhat, Gandhinagar-382428 (India)] [Institute for Plasma Research, Bhat, Gandhinagar-382428 (India); Ashwin, J. [Weizmann Institute of Science, Rehovot - 76100 (Israel)] [Weizmann Institute of Science, Rehovot - 76100 (Israel)

    2013-08-15

    In a simple method of low power nano-second double pulsed laser ablation experiment in collinear geometry, formation of high density strongly coupled plasma is demonstrated. Using time-resolved measurements of the Stark broadened line width and line intensity ratio of the emission lines, the density and temperature of the plasma were estimated respectively. In this experiment, it is shown that ions are strongly coupled (ion-ion coupling parameter comes out to be >4). For comparison, both single and double pulsed laser ablations are presented. For the estimated experimental plasma parameters, first principle Langevin dynamics simulation corroborates the existence of a strongly coupled regime.

  15. Comparison of laser ablation with spark discharge techniques used for nanoparticle production

    NASA Astrophysics Data System (ADS)

    Voloshko, Andrey; Colombier, Jean-Philippe; Itina, Tatiana E.

    2015-05-01

    Based on numerical modeling, we compare laser ablation and spark discharge as promising methods of nanoparticle formation. First, we consider spark discharge between parallel plate metal electrodes. Second, we investigate nanosecond laser ablation of a metal target. For both phenomena copper is chosen to be nanoparticle material and argon at atmospheric pressure is used as an ambient gas. Despite different energy inputs, both differences and similarities are revealed in the corresponding plasma properties. The time-evolution of the critical particle sizes are, however, found to be similar in both cases.

  16. Experimental and Analytical Investigation of Cemented Tungsten Carbide Ultra-Short Pulse Laser Ablation

    NASA Astrophysics Data System (ADS)

    Urbina, J. P. Calderón; Daniel, C.; Emmelmann, C.

    Ultra-short pulse laser processing of hard materials, such as cemented tungsten carbide, requires an accurate and agile experimental and analytical investigation to obtain adequate information and setting parameters to maximize ablation rate. Therefore, this study presents a systematic approach which, first, experimentally searches for the variables with the most significant influence on the objective using a design of experiments method; and second, analyzes by means of existing ablation theory the interaction of the material and laser taking into account the Beer-Lambert law and incubation effect.Therefore, this places a basis for future analytical-experimental validation of the examined material.

  17. Cavitation effect of holmium laser pulse applied to ablation of hard tissue underwater.

    PubMed

    Lü, Tao; Xiao, Qing; Xia, Danqing; Ruan, Kai; Li, Zhengjia

    2010-01-01

    To overcome the inconsecutive drawback of shadow and schlieren photography, the complete dynamics of cavitation bubble oscillation or ablation products induced by a single holmium laser pulse [2.12 microm, 300 micros (FWHM)] transmitted in different core diameter (200, 400, and 600 microm) fibers is recorded by means of high-speed photography. Consecutive images from high-speed cameras can stand for the true and complete process of laser-water or laser-tissue interaction. Both laser pulse energy and fiber diameter determine cavitation bubble size, which further determines acoustic transient amplitudes. Based on the pictures taken by high-speed camera and scanned by an optical coherent microscopy (OCM) system, it is easily seen that the liquid layer at the distal end of the fiber plays an important role during the process of laser-tissue interaction, which can increase ablation efficiency, decrease heat side effects, and reduce cost. PMID:20799845

  18. A Study on Removal of Shoulders at Laser Ablated Indium Tin Oxide Film Edge

    NASA Astrophysics Data System (ADS)

    Kim, Kwang Ho; Kwon, Sang Jik; Tak, Tae Oh

    2008-01-01

    A diode-pumped Q-switched Nd:YVO4 laser (?=1064 nm) was used for the fabrication of plasma display panel (PDP) bus electrodes. In the experiments, with the maskless laser direct patterning of indium tin oxide (ITO) films, the laser-ablated ITO patterns showed the formation of shoulders at the edge of the ITO lines and a ripplelike structure with the etched bottom compared with the chemically wet-etched ITO patterns. Using a Q-switched Nd:YVO4 laser and a galvanometric scanning system, 500 mm/s with a 40 kHz repetition rate was found to be appropriate for application to PDP manufacturing. By dipping the laser-ablated ITO films in the chemical etching solution for 30 s at 50 °C, the shoulders were effectively removed without affecting the discharging properties of ac-PDP.

  19. Rear-side picosecond laser ablation of indium tin oxide micro-grooves

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Wang, Wenjun; Mei, Xuesong; Liu, Bin; Zhao, Wanqin

    2015-06-01

    A comparative study of the fabrication of micro-grooves in indium tin oxide films by picosecond laser ablation for application in thin film solar cells is presented, evaluating the variation of different process parameters. Compared with traditional front-side ablation, rear-side ablation results in thinner grooves with varying laser power at a certain scan speed. In particular, and in contrast to front-side ablation, the width of the micro-grooves remains unchanged when the scan speed was changed. Thus, the micro-groove quality can be optimized by adjusting the scan speed while the groove width would not be affected. Furthermore, high-quality micro-grooves with ripple free surfaces and steep sidewalls could only be achieved when applying rear-side ablation. Finally, the formation mechanism of micro-cracks on the groove rims during rear-side ablation is analyzed and the cracks can be almost entirely eliminated by an optimization of the scan speed.

  20. Laser-induced plasma-assisted ablation (LIPAA): fundamental and industrial applications

    NASA Astrophysics Data System (ADS)

    Hanada, Y.; Sugioka, K.; Midorikawa, K.

    2006-05-01

    The laser-induced plasma-assisted ablation (LIPAA) process developed by our group, in which a single conventional pulsed laser is only used, makes it possible to perform high-quality and high-speed glass microfabrication. Up to the present, this process has been widely applied for micromachining of various transparent hard and soft materials. In this process, the laser beam first passes through the glass substrate since the laser beam has no absorption by the substrate. Then, the transmitted beam is absorbed by a solid target (typically a metal), located behind the substrate so that the target is ablated, resulting in plasma generation. Due to the interaction of the laser beam and the laser-induced plasma, significant ablation takes place at the rear surface of the substrate. Recently, we have developed the proto-type LIPAA system using a second harmonic of diode pumped Q-switched Nd:YAG laser for the practical use. In this paper, we demonstrate micromachining, crack-free marking and color marking of glass materials. Additionally, selective metallization of glass and polyimide by the LIPAA process followed by metal chemical-plating is investigated. A possible mechanism of LIPAA is also discussed based on the results from double pulse irradiation using near-IR fs laser, transient absorption measurement and plasma-conductivity measurement.

  1. Laser-plasma interaction and plasma enhancement by ultrashort double-pulse ablation

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Shin, Yung C.

    2015-07-01

    In this study, the laser-plasma interaction and the resultant plasma enhancement by ultrashort double-pulse ablation of silicon are investigated. It is found that by carefully selecting inter-pulse delay, the plasma temperature and electron number density can be effectively increased, compared to the case of single-pulse ablation. The strong plasma enhancement is observed at long-pulse delay (above 20 ps), companied by the ablation rate suppression. At short-pulse delay (below 20 ps), strong ablation rate enhancement is observed, with no plasma enhancement. The spatial analysis of plasma temperature shows that the second pulse energy is mainly absorbed by the front portion of the plasma, where the temperature is increased the most. The plasma reheating leads to a faster expansion of the plasma.

  2. Corneal tissue ablation using 6.1 ?m quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Huang, Yong; Kang, Jin U.

    2012-03-01

    High absorption property of tissues in the IR range (?> 2 ?m) results in effective tissue ablation, especially near 3 ?m. In the mid-infrared range, wavelengths of 6.1 ?m and 6.45 ?m fall into the absorption bands of the amide protein groups Amide-I and Amide-II, respectively. They also coincide with the deformation mode of water, which has an absorption peak at 6.1 ?m. This coincidence makes 6.1 ?m laser a better ablation tool that has promising effectiveness and minimum collateral damages than 3 ?m lasers. In this work, we performed bovine corneal ablation test in-vitro using high-power 6.1?m quantum cascade laser (QCL) operated at pulse mode. Quantum cascade laser has the advantages of low cost, compact size and tunable wavelength, which makes it great alternative Mid-IR light source to conventional tunable free-electron lasers (FEL) for medical applications. Preliminary results show that effective corneal stroma craters were achieved with much less collateral damage in corneal tissue that contains less water. Future study will focus on optimizing the control parameters of QCL to attain neat and precise ablation of corneal tissue and development of high peak power QCL.

  3. New Combined Laser Ablation Platform Determines Cell Wall Chemistry (Fact Sheet)

    SciTech Connect

    Not Available

    2011-09-01

    NREL has designed and developed a combined laser ablation/pulsed sample introduction/mass spectrometry platform that integrates pyrolysis and/or laser ablation with resonance-enhanced multiphoton ionization (REMPI) time-of-flight mass spectrometry. Using this apparatus, we can measure the cell wall chemical composition of untreated biomass materials. Understanding the chemical composition of untreated biomass is key to both the biochemical and thermochemical conversion of lignocellulosic biomass to biofuels. In the biochemical conversion process, the new technique provides a better understanding of the chemistry of lignin and will improve accessibility to plant sugars. In thermochemical conversion, the information provided by the new technique may help to reduce the formation of unwanted byproducts during gasification. NREL validated the ability of the system to detect pyrolysis products from plant materials using poplar, a potentially high-impact bioenergy feedstock. In the technique, biomass vapors are produced by laser ablation using the 3rd harmonic of an Nd:YAG laser (355 nm). The resulting vapors are entrained in a free jet expansion of helium, then skimmed and introduced into an ionization region. REMPI is used to ionize the vapors because it is highly sensitive for detecting lignin and aromatic metabolites. The laser ablation method was used to selectively volatilize specific plant tissues and detect lignin-based products from the vapors with enhanced sensitivity. This will allow the determination of lignin distribution in future biomass studies.

  4. Dental ablation with 1064 nm, 500 ps, Diode pumped solid state laser: A preliminary study

    PubMed Central

    Fornaini, Carlo; Cucinotta, Annamaria; Merigo, Elisabetta; Vescovi, Paolo; Selleri, Stefano

    2013-01-01

    Background: The Er:YAG laser in conservative dentistry is. good alternative to conventional instruments. Though several studies show the advantages of these devices, some drawbacks and unsolved problems are still present, such as the cost of the device and the large dimensions of the equipment. Purpose: In the present study, the effectiveness of dental surface ablation with a picosecond infrared diode-pumped solid-state (DPSS) laser was investigated. In vitro tests on extracted human teeth were carried out, with assessment of the ablation quality in the tooth and thermal increase inside the pulp chamber. Materials and Methods: A solid-state picosecond laser was used for the experiments. The samples were exposed to laser energy at 1064 nm at a frequency of 30 kHz and a 500 ps pulse width. The target teeth were cooled during exposures. The internal temperature of the pulp chamber was monitored with. thermocouple. Results: Optical microscope images showed effective ablation with the absence of carbonisation and micro-cracks. The cooling maintained the temperature rise in the pulp chamber below the permitted 5.5°C. Discussion: The main problem with the use of lasers in dentistry when teeth are the target is the heat generated in the pulp chamber of the target teeth. With lasers operating in the femtosecond mode, a better management of the internal temperature is possible, but is offset by the high cost of such devices. With the ps domain system used in the present study together with cooling using chilled water, effective and clean ablation could be achieved with a controlled thermal effect in the pulp chamber. Conclusions: In this preliminary study with a picosecond domain DPSS laser using water cooling for the target, effective hard tissue ablation was achieved keeping the thermal increase in the pulp within the permitted range. The results suggest that this system could be used in clinical practice with appropriate modifications. PMID:24204093

  5. Laser-induced hard tissue ablation by assisted with a liquid film on target tissue surface

    NASA Astrophysics Data System (ADS)

    Zhang, Xianzeng; Zhao, Haibin; Zhan, Zhenlin; Ye, Qing; Xie, Shusen

    2010-11-01

    The objective of this study was to investigate the influence of an applied water film on bone hard tissue ablation by pulse CO2 laser. Fresh bovine shank bone in vitro used in the experiment were put on a PC-controlled motorized linear drive stage and moved repeatedly through focused beam of laser without and with a water film of 0.4 mm and 1 mm on target tissue. The wavelength of pulse CO2 laser was 10.64 ?m, pulse repetition rate was 60 Hz, the energy density was 18-84 J/cm2 and the beam diameter of about 400 ?m. The moving speed of stage was 12 mm/s, scanning times was 5. The surface morphology and microstructure of ablation grooves were examined by stereomicroscope and scanning electron microscope (SEM) respectively. The geometry of the groove was measured with optical coherence tomography (OCT), and the thermal injury was examined by histology. It shows that water film on the target tissue surface plays an important role during the ablation process. A proper thickness of water film applied to target tissue surface could improve the regular of cut shape, smooth the cut surface, produce the same or even larger ablation rate and efficiency, and reduce the thermal injury around the groove by compared with dry ablation condition. Moreover, the addition of water could alter the microstructure of bone sample.

  6. Pulsed laser ablation deposition of yttrium iron garnet and cerium-substituted YIG films

    NASA Astrophysics Data System (ADS)

    Ibrahim, N. B.; Edwards, C.; Palmer, S. B.

    2000-10-01

    Yttrium iron garnet (YIG) thin films were grown on gadolinium gallium garnet substrates using pulsed laser ablation deposition (PLAD) with a XeCl excimer laser. Films were grown up to over 2 ?m thick, however cracking proved to be a problem for films over 1 ?m thick. The lattice parameter(s) of the films and the substrates were measured and indicated that the film/substrate structure was bending to accommodate strain due to the lattice mismatch. The films had saturation magnetisation values close to that of bulk YIG and were isotropic in the film plane. The magnetisation data also indicate stress-induced uniaxial isotropy. The ablation conditions were varied to produce uncracked films with low droplet densities. YIG melts incongruently during the laser ablation process and cone-like structures form on the ablation target lowering the ablation rates. Cerium-substituted YIG films were also grown in both oxygen and argon atmospheres, substituting cerium into YIG increases the lattice parameter and hence reduces the strain. The Ce-YIG film grown in argon was greenish indicating that cerium was in the desired oxidation state.

  7. On the Properties of Plastic Ablators in Laser-Driven Material Dynamics Experiments

    SciTech Connect

    Swift, D C; Kraus, R G

    2007-11-15

    Radiation hydrodynamics simulations were used to study the effect of plastic ablators in laser-driven shock experiments. The sensitivity to composition and equation of state was found to be 5-10% in ablation pressure. As was found for metals, a laser pulse of constant irradiance gave a pressure history which decreased by several percent per nanosecond. The pressure history could be made more constant by adjusting the irradiance history. The impedance mismatch with the sample gave an increase o(100%) in the pressure transmitted into the sample, for a reduction of several tens of percent in the duration of the peak load applied to the sample, and structured the release history by adding a release step to a pressure close to the ablation pressure. Algebraic relations were found between the laser pulse duration, the ablator thickness, and the duration of the peak pressure applied to the sample, involving quantities calculated from the equations of state of the ablator and sample using shock dynamics.

  8. Heat generation caused by ablation of dental restorative materials with an ultra short pulse laser (USPL) system

    NASA Astrophysics Data System (ADS)

    Braun, Andreas; Wehry, Richard; Brede, Olivier; Frentzen, Matthias; Schelle, Florian

    2011-03-01

    The aim of this study was to assess heat generation in dental restoration materials following laser ablation using an Ultra Short Pulse Laser (USPL) system. Specimens of phosphate cement (PC), ceramic (CE) and composite (C) were used. Ablation was performed with an Nd:YVO4 laser at 1064 nm and a pulse length of 8 ps. Heat generation during laser ablation depended on the thickness of the restoration material. A time delay for temperature increase was observed in the PC and C group. Employing the USPL system for removal of restorative materials, heat generation has to be considered.

  9. Medical Applications of Laser Spectroscopy

    NASA Astrophysics Data System (ADS)

    Svanberg, S.

    1989-01-01

    Lasers are finding many applications in medicine and biology. While most laser use focuses on the heat generation of the laser beam interacting with tissue, spectroscopic aspects play a more dominating part in a number of emerging applications. Tumour-seeking agents, such as hematoporphyrin derivative (HPD), in combination with laser radiation provide new possibilities for cancer tumour detection and treatment. The fluorescence emission from tissue irradiated with UV light can be used for tumour localization. Natural tissue fluorescence as well as fluorescence due to injected HPD can be utilized. Results from studies on animals and from clinical applications are reported. The use of fluorescence for identifying atherosclerotic plaque in human vessels is illustrated. Spectroscopic analysis of the laser-induced plasma obtained when a high-power, pulsed laser beam interacts with tissue is also discussed with applications to plaque removal and laser fragmentation of kidney- and gall-stones.

  10. Picosecond laser ablation system with process control by optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Targowski, Piotr; Ostrowski, Roman; Marczak, Jan; Sylwestrzak, Marcin; Kwiatkowska, Ewa A.

    2009-07-01

    In this contribution we describe an apparatus for precise laser ablation of delicate layers, like varnish on pictures. This specific case is very demanding. First of all any changes in colour of remaining varnish layer as well as underneath paint layers are unacceptable. This effect may be induced photochemically or thermically. In the first case strong absorption of the radiation used will eliminate its influence on underlying strata. The thermal effect is limited to so called heat affected zone (HAZ). In addition to colour change, a mechanical damage caused by overheating of the structure adjacent to ablated region should be considered also. All kinds of treads must be carefully eliminated in order to make laser ablation of varnish commonly accepted alternative to chemical and/or mechanical treatments [1]. Since the varnish ablation process is obviously irreversible its effective monitoring is very important to make it safe and trusted. As we showed previously [2-6] optical coherence tomography (OCT) originated from medicine diagnostic method for examination and imaging of cross-sections of weakly absorbing objects can be used for this task. OCT utilises infrared light for non-invasive structure examination and has been under consideration for the examining of objects of art since 2004 [7-10]. In this case the in-depth (axial) resolution is obtained by means of interference of light of high spatial (to ensure sensitivity) and very low temporal coherence (to ensure high axial resolution). In practice, IR sources of bandwidths from 25 to 150 nm are utilised. Resolutions obtained range from 15 down to 2 ?m in the media of refracting index equal 1.5. In this contribution we expand application of OCT to space resolved determination of ablation rates, separately for every point of examined area. Such data help in better understanding of the ablation process, fine tuning the laser and finally permit increase of the safety of the ablation process.

  11. Single-shot and single-spot measurement of laser ablation threshold for carbon nanotubes

    E-print Network

    Lednev, Vasily N; Obraztsova, Elena D; Kudryashov, Sergey I; Bunkin, Alexey F

    2013-01-01

    A simple and convenient procedure for single-shot, single-spot ablation threshold measurement has been developed. It is based on the employment of cylindrical lens to obtain elliptical Gaussian laser spot. The ablated spot chords which are parallel to the minor axis were measured across the spot major axis which is proportional to the fluence cross-section thus providing wide range dependence of damaged spot size versus fluence in one spot measurement. For both conventional and new-developed procedures the ablation threshold for typical Nd:YAG laser parameters (1064 nm, 10 ns) has been measured as 50 mJ/cm2 which is one order of magnitude lower than that for a bulk graphite.

  12. Single-shot and single-spot measurement of laser ablation threshold for carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lednev, Vasily N.; Pershin, Sergey M.; Obraztsova, Elena D.; Kudryashov, Sergey I.; Bunkin, Alexey F.

    2013-02-01

    A simple and convenient procedure for single-shot, single-spot ablation threshold measurement is developed. It is based on the employment of cylindrical lens to obtain an elliptical Gaussian laser spot. The ablated spot chords that are parallel to the minor axis are measured across the spot major axis, which is proportional to the fluence cross-section, thus providing wide range dependence of damaged spot size versus fluence in one spot measurement. For both conventional and newly developed procedures the ablation threshold for typical Nd?:?YAG laser parameters (1064 nm, 10 ns) is measured as 50 ± 5 mJ cm-2, which is one order of magnitude lower than that for bulk graphite.

  13. Self-organized structure formation on the bottom of femtosecond laser ablation craters in glass

    NASA Astrophysics Data System (ADS)

    Seifert, G.; Kaempfe, M.; Syrowatka, F.; Harnagea, C.; Hesse, D.; Graener, H.

    2005-09-01

    Using femtosecond laser pulses (150 fs duration at ?=400 nm) for ablation experiments on glass samples with and without enclosed silver nanoparticles, characteristic sub-micrometer surface topologies are observed on the flat bottom of the ablation craters produced. The structures show increasing order towards periodic ripple-like features with an increasing number of successive pulses applied. Depending on sample and experimental conditions, the spatial periodicity varies between 340 nm and 1900 nm, despite a constant laser wavelength and incidence angle. An analysis based on electron and atomic force microscopy of the structures indicates that the formation of the ripples in this work is due to instabilities and self-organization of the surface relaxation after ablation.

  14. Preparation of silver nanoparticles in virgin coconut oil using laser ablation

    PubMed Central

    Zamiri, Reza; Azmi, B Z; Sadrolhosseini, Amir Reza; Ahangar, Hossein Abbastabar; Zaidan, A W; Mahdi, M A

    2011-01-01

    Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10?8, 1.6 × 10?8, 2.4 × 10?8, respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method. PMID:21289983

  15. Preparation of silver nanoparticles in virgin coconut oil using laser ablation.

    PubMed

    Zamiri, Reza; Azmi, B Z; Sadrolhosseini, Amir Reza; Ahangar, Hossein Abbastabar; Zaidan, A W; Mahdi, M A

    2011-01-01

    Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10(-8), 1.6 × 10(-8), 2.4 × 10(-8), respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method. PMID:21289983

  16. Gas-dynamic acceleration of laser-ablation plumes: Hyperthermal particle energies under thermal vaporization

    NASA Astrophysics Data System (ADS)

    Morozov, A. A.; Evtushenko, A. B.; Bulgakov, A. V.

    2015-02-01

    The expansion of a plume produced by low-fluence laser ablation of graphite in vacuum is investigated experimentally and by direct Monte Carlo simulations in an attempt to explain hyperthermal particle energies for thermally vaporized materials. We demonstrate that the translation energy of neutral particles, ˜2 times higher than classical expectations, is due to two effects, hydrodynamic plume acceleration into the forward direction and kinetic selection of fast particles in the on-axis region. Both effects depend on the collision number within the plume and on the particles internal degrees of freedom. The simulations allow ablation properties to be evaluated, such as ablation rate and surface temperature, based on time-of-flight measurements. Available experimental data on kinetic energies of various laser-produced particles are well described by the presented model.

  17. Focal Laser Ablation for Localized Prostate Cancer: Principles, Clinical Trials, and Our Initial Experience

    PubMed Central

    Lee, Ted; Mendhiratta, Neil; Sperling, Dan; Lepor, Herbert

    2014-01-01

    Focal therapy of prostate cancer is an evolving treatment strategy that destroys a predefined region of the prostate gland that harbors clinically significant disease. Although long-term oncologic control has yet to be demonstrated, focal therapy is associated with a marked decrease in treatment-related morbidity. Focal laser ablation is an emerging modality that has several advantages, most notably real-time magnetic resonance imaging (MRI) compatibility. This review presents the principles of laser ablation, the role of multiparametric MRI for delineating the site of significant prostate cancer, a summary of published clinical studies, and our initial experience with 23 patients, criteria for selecting candidates for focal prostate ablation, and speculation regarding future directions. PMID:25009445

  18. The thermoelastic basis of short pulsed laser ablation of biological tissue.

    PubMed Central

    Itzkan, I; Albagli, D; Dark, M L; Perelman, L T; von Rosenberg, C; Feld, M S

    1995-01-01

    Strong evidence that short-pulse laser ablation of biological tissues is a photomechanical process is presented. A full three-dimensional, time-dependent solution to the thermoelastic wave equation is compared to the results of experiments using an interferometric surface monitor to measure thermoelastic expansion. Agreement is excellent for calibrations performed on glass and on acrylic at low laser fluences. For cortical bone, the measurements agree well with the theoretical predictions once optical scattering is included. The theory predicts the presence of the tensile stresses necessary to rupture the tissue during photomechanical ablation. The technique is also used to monitor the ablation event both before and after material is ejected. PMID:7892208

  19. Characterization of Carbon Nitride Nanoparticles Prepared by Laser Ablation in Liquid for Optoelectronic Application

    NASA Astrophysics Data System (ADS)

    Khashan, Khawla S.; Mohsin, Mayyadah H.

    2015-05-01

    In this work, carbon nitride (C3N4) nanoparticles (NPs) were synthesized by pulse laser ablation of graphite in ammonium solution, and deposited on silicon substrates by spray. Fourier transform infrared spectroscopy (FTIR), UV-visible spectrophotometer and transmission electron microscopy (TEM) were used to study bonding, absorption, size and morphology of the produce NPs. The FTIR absorption peaks at 2121.6, 1631.7 and 1384 cm-1 stretching vibration bond, it is inferred for the C?N, C=N and C-N, respectively. Bonds suggests the formation, C3N4 NPs. UV absorption peaks coincide with the electronic transitions corresponding to the formation, C3N4 NPs with 3.98 eV optical bandgap. The TEM show the aggregation of the C3N4 NPs with size ranges from 4 to 83 nm, and also the leaf-like structure are shown in the structure of C3N4 suspension. High performance rectifying C3N4/Si heterojunction with a rectifying ratio exceeding 345 at V = 5V was obtained, with high photoresponsivity of 2.33 A/W at 600 nm.The results show that C3N4 NPs on silicon substrates will act as very good candidates for making high efficiency photodiodes.

  20. Dynamics of the plumes produced by ultrafast laser ablation of metals

    SciTech Connect

    Donnelly, T.; Lunney, J. G. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Amoruso, S.; Bruzzese, R.; Wang, X. [Dipartimento di Scienze Fisiche and CNR-SPIN, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Ni, X. [Department of Electronic Engineering, Tianjin University of Technology and Education, Tianjin 300222 (China)

    2010-08-15

    We have analyzed ultrafast laser ablation of a metallic target (Nickel) in high vacuum addressing both expansion dynamics of the various plume components (ionic and nanoparticle) and basic properties of the ultrafast laser ablation process. While the ion temporal profile and ion angular distribution were analyzed by means of Langmuir ion probe technique, the angular distribution of the nanoparticulate component was characterized by measuring the thickness map of deposition on a transparent substrate. The amount of ablated material per pulse was found by applying scanning white light interferometry to craters produced on a stationary target. We have also compared the angular distribution of both the ionic and nanoparticle components with the Anisimov model. While the agreement for the ion angular distribution is very good at any laser fluence (from ablation threshold up to {approx_equal}1 J/cm{sup 2}), some discrepancies of nanoparticle plume angular distribution at fluencies above {approx_equal}0.4 J/cm{sup 2} are interpreted in terms of the influence of the pressure exerted by the nascent atomic plasma plume on the initial hydrodynamic evolution of the nanoparticle component. Finally, analyses of the fluence threshold and maximum ablation depth were also carried out, and compared to predictions of theoretical models. Our results indicate that the absorbed energy is spread over a length comparable with the electron diffusion depth L{sub c} ({approx_equal}30 nm) of Ni on the timescale of electron-phonon equilibration and that a logarithmic dependence is well-suited for the description of the variation in the ablation depth on laser fluence in the investigated range.