Ablated Material

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Renato Zenobi - One of the best experts on this subject based on the ideXlab platform.

  • Material ejection and redeposition following atmospheric pressure near field laser ablation on molecular solids
    Analytical and Bioanalytical Chemistry, 2010
    Co-Authors: Liang Zhu, Gerardo Gamez, Thomas A Schmitz, Frank Krumeich, Renato Zenobi
    Abstract:

    Near-field laser ablation (NF-LA) coupled with mass spectrometry (MS) is very promising for highly spatially resolved chemical analyses on various substrates at atmospheric pressure, for example, in Materials and life science applications. Although nanoscale sample craters can be produced routinely, no molecular mass spectra of Ablated Material from craters of ≤1 µm diameter have ever been acquired by NF-LA MS at atmospheric pressure. Some of the pressing questions are thus how much of the Ablated Material is transported into the mass spectrometer and in what form. Therefore, Material redeposition on the near-field tip’s surface from laser ablation of molecular solids was characterized with scanning electron microscopy. The crater profiles were studied by scanning probe microscopy. The results shown in this study demonstrate that there could be as much as 70% of the Ablated Material deposited on the near-field tip’s surface. The redeposited products were found to be confined to a height of ~50 µm, thus suggesting that most components inside near-field ablation plumes propagate about the same distance for both anthracene and tris(8-hydroxyquinolinato)aluminum. Nanoparticles Ablated from craters of ≤1 µm diameter are clearly observed. Furthermore, observation of tips after ablation of an anthracene surface angled at 60° with respect to a horizontal surface shows that the direction of the near-field ablation plume is neither in the direction of the surface normal nor towards the axis of incident laser beam but deflected further away from surface normal.

  • Material ejection and redeposition following atmospheric pressure near-field laser ablation on molecular solids
    Analytical and Bioanalytical Chemistry, 2010
    Co-Authors: Gerardo Gamez, Thomas A Schmitz, Frank Krumeich, Renato Zenobi
    Abstract:

    Near-field laser ablation (NF-LA) coupled with mass spectrometry (MS) is very promising for highly spatially resolved chemical analyses on various substrates at atmospheric pressure, for example, in Materials and life science applications. Although nanoscale sample craters can be produced routinely, no molecular mass spectra of Ablated Material from craters of ≤1 µm diameter have ever been acquired by NF-LA MS at atmospheric pressure. Some of the pressing questions are thus how much of the Ablated Material is transported into the mass spectrometer and in what form. Therefore, Material redeposition on the near-field tip’s surface from laser ablation of molecular solids was characterized with scanning electron microscopy. The crater profiles were studied by scanning probe microscopy. The results shown in this study demonstrate that there could be as much as 70% of the Ablated Material deposited on the near-field tip’s surface. The redeposited products were found to be confined to a height of ~50 µm, thus suggesting that most components inside near-field ablation plumes propagate about the same distance for both anthracene and tris(8-hydroxyquinolinato)aluminum. Nanoparticles Ablated from craters of ≤1 µm diameter are clearly observed. Furthermore, observation of tips after ablation of an anthracene surface angled at 60° with respect to a horizontal surface shows that the direction of the near-field ablation plume is neither in the direction of the surface normal nor towards the axis of incident laser beam but deflected further away from surface normal. Figure Material redeposition on the near-field tip's surface from laser ablation of molecular solids was characterized with scanning electron microscopy.

Stephan Barcikowski - One of the best experts on this subject based on the ideXlab platform.

  • target geometry and rigidity determines laser induced cavitation bubble transport and nanoparticle productivity a high speed videography study
    Physical Chemistry Chemical Physics, 2016
    Co-Authors: Sebastian Kohsakowski, Philipp Wagener, Anton Plech, Bilal Gokce, Rie Tanabe, Yoshiro Ito, Stephan Barcikowski
    Abstract:

    Laser-induced cavitation has mostly been studied in bulk liquid or at a two-dimensional wall, although target shapes for the particle synthesis may strongly affect bubble dynamics and interfere with particle productivity. We investigated the dynamics of the cavitation bubble induced by pulsed-laser ablation in liquid for different target geometries with high-speed laser microsecond videography and focus on the collapse behaviour. This method enables us observations in a high time resolution (intervals of 1 μs) and single-pulse experiments. Further, we analyzed the nanoparticle productivity, the sizes of the synthesized nanoparticles and the evolution of the bubble volume for each different target shape and geometry. For the ablation of metal (Ag, Cu, Ni) wire tips a springboard-like behaviour after the first collapse is observed which can be correlated with vertical projectile motion. Its turbulent friction in the liquid causes a very efficient transport and movement of the bubble and Ablated Material into the bulk liquid and prevents particle redeposition. This effect is influenced by the degree of freedom of the wire as well as the Material properties and dimensions, especially the Young's modulus. The most efficient and largest bubble movement away from the wire was observed for a thin (500 μm) silver wire with velocities up to 19.8 m s−1 and for Materials with a small Young's modulus and flexural rigidity. We suggest that these observations may contribute to upscaling strategies and increase of particle yield towards large synthesis of colloids based on targets that may continuously be fed.

  • dynamics of silver nanoparticle formation and agglomeration inside the cavitation bubble after pulsed laser ablation in liquid
    Physical Chemistry Chemical Physics, 2013
    Co-Authors: Philipp Wagener, Shyjumon Ibrahimkutty, Andreas Menzel, Anton Plech, Stephan Barcikowski
    Abstract:

    The formation of nanoparticles within the laser-induced cavitation bubble is studied in situ using small angle X-ray scattering with high spatiotemporal resolution. Directly after laser ablation, two different particle fractions consisting of compact primary particles of 8–10 nm size and agglomerates of 40–60 nm size are formed. The abundance of these species is strongly influenced by the dynamics of the oscillating cavitation bubble. Primary particle mass is most abundant during maximal expansion of the first bubble and reappears a little weaker in the rebound. In contrast to this, the mass abundance of agglomerates is relatively low in the first bubble but strongly increases during first bubble collapse and following rebound. Although most of the Ablated Material is trapped inside the bubble and follows its oscillation, a minor fraction of both species could be detected outside the cavitation bubble even before its final collapse.

Alexander Wokaun - One of the best experts on this subject based on the ideXlab platform.

  • pressure and temperature dependence of the laser induced plasma plume dynamics
    Journal of Applied Physics, 2016
    Co-Authors: Alejandro Ojedagp, C W Schneider, Thomas Lippert, Alexander Wokaun
    Abstract:

    The influence of different background gases and substrate heating on the plasma plume dynamics from silver ablation is investigated by species selected time and space resolved imaging. The results provide a time-resolved understanding on how those process parameters affect the expansion: from a free expansion in vacuum with velocities exceeding 20 000 m/s to a very slow expansion in Ar at 1 × 10−1 mbar with arrival velocities of 280 m/s. In addition, we observe a rebound of the Ablated Material on the substrate holder leading to a re-coating of the Ablated target. At 1 × 10−1 mbar, it seems that the expansion of the plasma plume displaces a considerable portion of the background gas and traps it against the frontal area of the substrate holder. This leads to a transient high local pressure just above the substrate. In the case of Ar, the rebound is enhanced due to inelastic scattering, whereas for an O2 background, an area of high reactivity/emission in addition to the rebound is created. Imaging of selec...

  • laser induced forward transfer of organic led building blocks studied by time resolved shadowgraphy
    Journal of Physical Chemistry C, 2010
    Co-Authors: Romain Fardel, Thomas Lippert, Matthias Nagel, Frank Nuesch, Alexander Wokaun
    Abstract:

    The patterned deposition of thin films is essential for many technological applications. One promising Material deposition technique is laser-induced forward transfer (LIFT), where a thin layer coated on a transparent substrate is Ablated by a laser pulse passing through the substrate. The Ablated Material is collected on a nearby receiver substrate in a pattern defined by the laser. The technique can be applied to heat and light sensitive Materials, provided that they are not directly irradiated by the laser pulse. For this application, a sacrificial layer is introduced between the substrate and the transfer layer so that the laser energy is converted into mechanical propulsion while protecting the sensitive layer from radiation. In this work, the application of a triazene polymer as a sacrificial layer for LIFT has been studied with the final goal of transferring organic light-emitting diode (OLED) pixels. Donor films made of a stack of triazene polymer, metal, and optionally an electroluminescent polym...

Gerardo Gamez - One of the best experts on this subject based on the ideXlab platform.

  • Material ejection and redeposition following atmospheric pressure near field laser ablation on molecular solids
    Analytical and Bioanalytical Chemistry, 2010
    Co-Authors: Liang Zhu, Gerardo Gamez, Thomas A Schmitz, Frank Krumeich, Renato Zenobi
    Abstract:

    Near-field laser ablation (NF-LA) coupled with mass spectrometry (MS) is very promising for highly spatially resolved chemical analyses on various substrates at atmospheric pressure, for example, in Materials and life science applications. Although nanoscale sample craters can be produced routinely, no molecular mass spectra of Ablated Material from craters of ≤1 µm diameter have ever been acquired by NF-LA MS at atmospheric pressure. Some of the pressing questions are thus how much of the Ablated Material is transported into the mass spectrometer and in what form. Therefore, Material redeposition on the near-field tip’s surface from laser ablation of molecular solids was characterized with scanning electron microscopy. The crater profiles were studied by scanning probe microscopy. The results shown in this study demonstrate that there could be as much as 70% of the Ablated Material deposited on the near-field tip’s surface. The redeposited products were found to be confined to a height of ~50 µm, thus suggesting that most components inside near-field ablation plumes propagate about the same distance for both anthracene and tris(8-hydroxyquinolinato)aluminum. Nanoparticles Ablated from craters of ≤1 µm diameter are clearly observed. Furthermore, observation of tips after ablation of an anthracene surface angled at 60° with respect to a horizontal surface shows that the direction of the near-field ablation plume is neither in the direction of the surface normal nor towards the axis of incident laser beam but deflected further away from surface normal.

  • Material ejection and redeposition following atmospheric pressure near-field laser ablation on molecular solids
    Analytical and Bioanalytical Chemistry, 2010
    Co-Authors: Gerardo Gamez, Thomas A Schmitz, Frank Krumeich, Renato Zenobi
    Abstract:

    Near-field laser ablation (NF-LA) coupled with mass spectrometry (MS) is very promising for highly spatially resolved chemical analyses on various substrates at atmospheric pressure, for example, in Materials and life science applications. Although nanoscale sample craters can be produced routinely, no molecular mass spectra of Ablated Material from craters of ≤1 µm diameter have ever been acquired by NF-LA MS at atmospheric pressure. Some of the pressing questions are thus how much of the Ablated Material is transported into the mass spectrometer and in what form. Therefore, Material redeposition on the near-field tip’s surface from laser ablation of molecular solids was characterized with scanning electron microscopy. The crater profiles were studied by scanning probe microscopy. The results shown in this study demonstrate that there could be as much as 70% of the Ablated Material deposited on the near-field tip’s surface. The redeposited products were found to be confined to a height of ~50 µm, thus suggesting that most components inside near-field ablation plumes propagate about the same distance for both anthracene and tris(8-hydroxyquinolinato)aluminum. Nanoparticles Ablated from craters of ≤1 µm diameter are clearly observed. Furthermore, observation of tips after ablation of an anthracene surface angled at 60° with respect to a horizontal surface shows that the direction of the near-field ablation plume is neither in the direction of the surface normal nor towards the axis of incident laser beam but deflected further away from surface normal. Figure Material redeposition on the near-field tip's surface from laser ablation of molecular solids was characterized with scanning electron microscopy.

R.l. Mccrory - One of the best experts on this subject based on the ideXlab platform.

  • Deceleration phase of inertial confinement fusion implosions
    Physics of Plasmas, 2002
    Co-Authors: K S Anderson, D. D. Meyerhofer, R.l. Mccrory, S. Skupsky, Richard Town
    Abstract:

    A model for the deceleration phase and marginal ignition of imploding capsules is derived by solving a set of ordinary differential equations describing the hot-spot energy balance and the shell dynamics including the return shock propagation. It is found that heat flux leaving the hot spot goes back in the form of internal energy and PdV work of the Material Ablated off the inner-shell surface. Though the hot-spot temperature is reduced by the heat conduction losses, the hot-spot density increases due to the Ablated Material in such a way that the hot-spot pressure is approximately independent of heat conduction. For hot-spot temperatures exceeding approximately 7 keV, the ignition conditions are not affected by heat conduction losses that are recycled into the hot spot by ablation. Instead, the only significant internal energy loss is due to the hot-spot expansion tamped by the surrounding shell. The change of adiabat induced by the shock is also calculated for marginally igniting shells, and the relati...

  • hot spot dynamics and deceleration phase rayleigh taylor instability of imploding inertial confinement fusion capsules
    Physics of Plasmas, 2001
    Co-Authors: M. Umansky, V. Lobatchev, R.l. Mccrory
    Abstract:

    A model for the deceleration phase of imploding inertial confinement fusion capsules is derived by solving the conservation equations for the hot spot. It is found that heat flux leaving the hot spot goes back in the form of internal energy and pdV work of the Material Ablated off the inner shell surface. Though the hot-spot temperature is reduced by the heat conduction losses, the hot-spot density increases due to the Ablated Material in such a way that the hot-spot pressure is approximately independent of heat conduction. For direct-drive National Ignition Facility-like capsules, the ablation velocity off the shell inner surface is of the order of tens μm/ns, the deceleration of the order of thousands μm/ns2, and the density-gradient scale length of the order a few μm. Using the well-established theory of the ablative Rayleigh–Taylor instability, it is shown that the growth rates of the deceleration phase instability are significantly reduced by the finite ablative flow and the unstable spectrum exhibits a cutoff for mode numbers of about l≈90.