Quadrupole Mass Spectroscopy

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Alan Furlan - One of the best experts on this subject based on the ideXlab platform.

  • Photodissociation of an alkyl nitrite at a liquid surface: flight-time distributions of NO and HNO
    Chemical Physics Letters, 1999
    Co-Authors: Alan Furlan
    Abstract:

    Abstract The photochemistry at a gas–liquid interface was investigated by time-of-flight Quadrupole Mass Spectroscopy. A liquid film of dodecyl dinitrite (ONO(CH 2 ) 12 ONO), dissolved in squalane (C 30 H 62 ), was irradiated with low-fluence laser pulses at 275 and 355 nm. The translational temperature of most NO and all HNO desorbate is in equilibrium with the liquid. A quantitative simulation requires that diffusion and radical reactions in the liquid are included. Ejection of hyperthermal NO ( T trans =500–2200 K) was also observed. The results are compared to those of alkyl nitrite monomers, clusters and solid films.

  • PHOTODISSOCIATION OF A SURFACE-ACTIVE SPECIES AT A LIQUID SURFACE : A STUDY BY TIME-OF-FLIGHT Spectroscopy
    The Journal of Physical Chemistry B, 1999
    Co-Authors: Alan Furlan
    Abstract:

    The photochemistry at a gas−liquid interface was investigated by time-of-flight/Quadrupole Mass Spectroscopy (TOF/QMS). A thin liquid film of 4-iodobenzoic acid (IBA), dissolved in glycerol, was irradiated with nanosecond laser pulses at 275 nm. Atomic and molecular iodine were the only photoproducts leaving the liquid after a low-fluence laser pulse (

  • Photoproducts ejected from liquid surfaces: The importance of photochemical, diffusional, kinetic, and surface structural effects
    The Journal of Chemical Physics, 1998
    Co-Authors: Alan Furlan, Gregory E. Hall
    Abstract:

    Gas-phase products of liquid surface photochemistry in high vacuum were analyzed by time-of-flight/Quadrupole Mass Spectroscopy. A thin liquid film of a long-chain alkyl iodide, C18H37I, dissolved in squalane (C30H62) was irradiated with nanosecond laser pulses at 275 nm. The photoproducts leaving the liquid after a low-fluence laser pulse (0.5 mJ/cm2) were I, HI, and I2. Since these species may desorb at times delayed by diffusion in the liquid phase, time-of-flight profiles were also recorded using a chopper wheel in front of the surface. This allowed a reconstruction of the time-dependent flux from the surface. The flight time distributions were compared to model calculations which take into account laser photolysis of C18H37I, diffusion and surface evaporation of I, HI, and I2, and the condensed-phase kinetics of radical reactions, and allow for a component of direct photodissociation of surface layer molecules, leading to hyperthermal I atoms. Simulations based on a comprehensive kinetic scheme are i...

Seung Min Park - One of the best experts on this subject based on the ideXlab platform.

  • Er3+ photoluminescence from Er-doped amorphous SiOx films prepared by pulsed laser deposition at room temperature: The effects of oxygen concentration
    Applied Physics Letters, 2003
    Co-Authors: Chang Hyun Bae, Sang Hwan Nam, Seung Min Park, Young Rae Jang, Keon-ho Yoo, Kyoungwan Park
    Abstract:

    We have fabricated Er-doped amorphous SiOx films by laser ablation of a Si:Er2O3 target in He atmosphere. The photoluminescence intensity at 1.54 μm was highly dependent on the oxygen content in the film, which turned out to be changed significantly by the ambient He pressure. Also, we have adopted time-of-flight Quadrupole Mass Spectroscopy to obtain kinetic energies of ionic species in a plume produced by laser ablation. Si and Er ions do not overlap spatially as they expand toward the Si substrate and Er ions impinge on the preformed SiOx layer.

  • Laser ablation dynamics of YBa2Cu3O7−x in an oxygen jet
    Journal of Applied Physics, 1999
    Co-Authors: Seung Min Park, Ji Youn Moon
    Abstract:

    Mass spectroscopic studies on a reactive laser ablation of YBa2Cu3O7−x at 266 and 1064 nm in a pulsed oxygen jet have been performed by direct sampling of ions escaping from a laser-induced plasma (plume). Energetics of the ions is studied by using a time-of-flight (TOF) Quadrupole Mass Spectroscopy. TOF spectra of metal ions consist of a fast and a slow component, but TOF spectra of metal oxide ions show single broad distributions. Significant changes in the relative enrichment of metal oxide and oxygen ions and their TOF distributions are observed by adding oxygen molecules to the plume. Formation mechanisms of each ion are investigated by analyzing the TOF spectra with O2 pulse on and off. The dependences of the TOF spectra on the laser wavelengths and their fluences are also examined to elucidate the acceleration mechanisms of ions as well as photochemical phenomena in the plume.

  • Laser ablation of graphite in an oxygen jet
    The Journal of Chemical Physics, 1998
    Co-Authors: Seung Min Park, Ji Youn Moon
    Abstract:

    Mass spectroscopic studies on a reactive laser ablation of graphite at 1064 nm in a pulsed oxygen jet have been performed. Significant changes in the relative enrichment of carbon ions including anomalous enrichment of C2+ ions as well as formation of CO+, C2O+, and C3O+ ions are observed. Collision-induced dissociation and reactive scattering of carbon ions prevail by injection of the oxygen jet to the carbon plume. Energetics of the ions is studied by using a time-of-flight Quadrupole Mass Spectroscopy. Time-of-flight (TOF) spectra of each carbon ion consist of a fast and a slow component, which are considered to represent different formation mechanisms. By analyzing the changes of TOF spectra as a function of the delay time between the laser pulse and oxygen jet, we examine the effects of collisions on the formation of carbon ions.

  • Anomalous enrichment of C2+ ions by laser ablation of graphite in Ar jet
    The Journal of Chemical Physics, 1998
    Co-Authors: Seung Min Park, Heebyung Chae, Sangwook Wee, Inhyung Lee
    Abstract:

    The formation mechanisms of C1+, C2+, and C3+ ions by laser ablation of graphite are investigated using time-of-flight (TOF) Quadrupole Mass Spectroscopy. The laser ablation is performed in conjunction with a pulsed Ar expansion to elucidate the third-body effect on the formation of the small carbon cluster ions. Drastic enhancement of the C2+ ion signal is observed by an increase of the local pressure near the target, indicating that C2+ ions are efficiently formed by recombination of carbon atoms and subsequent ionization. The branching ratio of C1+, C2+, and C3+ ions and their mean translational energies are different from those of neutrals. Also, the TOF spectra for Cn+ ions show multiple peak structures, which implies that different mechanisms are involved in the formation of Cn+ ions.

  • Mass spectroscopic studies on the laser ablation of boron nitride
    Applied Surface Science, 1998
    Co-Authors: Heebyung Chae, Seung Min Park
    Abstract:

    Abstract The laser ablation of pyrolytic boron nitride (pBN) target was investigated by Quadrupole Mass Spectroscopy. The laser-correlated ion Mass spectra and time-of-flight (TOF) spectra were obtained. B + and B 2 + ions were detected but N + , N 2 + , or BN + ions were not observable. Instead, neutral N 2 molecules were detected. The velocity of B + ions and temperature of the plume were derived by shifted Maxwell–Boltzmann fitting of the TOF spectra of B + ions. At the laser fluence of 0.7 J/cm 2 , the velocity of B + ions was 21.7 km/s and the temperature was 15 765 K. Also studied were the effects of the retarding field on the energetics of B + ions. The space-charge effect was found to influence the dynamics of plume propagation significantly. The reactive laser ablation under N 2 atmosphere has been attempted by using a pulsed valve synchronized with the laser pulse.

Chang-il Kim - One of the best experts on this subject based on the ideXlab platform.

  • on the applicability of self consistent global model for the characterization of cl2 ar inductively coupled plasma
    Microelectronic Engineering, 2007
    Co-Authors: Alexander Efremov, Jong-gyu Kim, Gwan-ha Kim, A V Bogomolov, Chang-il Kim
    Abstract:

    This work reports the results on the influence of gas mixing ratio, gas pressure (0.26-3.3Pa) and input power (400-900W) on the Cl"2/Ar plasma parameters in the planar inductively-coupled plasma reactor. The investigation combined plasma diagnostics by Langmuir probe and Quadrupole Mass-Spectroscopy with plasma modelling given by the self-consistent global (0-dimensional) model with Maxwellian approximation for the electron energy distribution function. It was shown that, for the given range of experimental conditions, the model showed an outstanding agreement with the experiments and provided the near-to-adequate data on kinetics of plasma active species, their densities and fluxes.

  • On the applicability of self-consistent global model for the characterization of Cl2/Ar inductively coupled plasma
    Microelectronic Engineering, 2007
    Co-Authors: Alexander Efremov, Jong-gyu Kim, Gwan-ha Kim, A V Bogomolov, Chang-il Kim
    Abstract:

    This work reports the results on the influence of gas mixing ratio, gas pressure (0.26-3.3Pa) and input power (400-900W) on the Cl"2/Ar plasma parameters in the planar inductively-coupled plasma reactor. The investigation combined plasma diagnostics by Langmuir probe and Quadrupole Mass-Spectroscopy with plasma modelling given by the self-consistent global (0-dimensional) model with Maxwellian approximation for the electron energy distribution function. It was shown that, for the given range of experimental conditions, the model showed an outstanding agreement with the experiments and provided the near-to-adequate data on kinetics of plasma active species, their densities and fluxes.

  • surface etching mechanism of bi4 xlaxti3o12 thin films using Quadrupole Mass Spectroscopy
    Journal of Vacuum Science and Technology, 2006
    Co-Authors: Jong-gyu Kim, Gwan-ha Kim, Chang-il Kim
    Abstract:

    The etching mechanism of (Bi4−xLax)Ti3O12 (BLT) thin films in Ar∕Cl2 inductively coupled plasma (ICP) was investigated as a function of gas mixing ratios, process pressure, and ICP powers at fixed other conditions. Etch rates were measured by using an α-step surface profiler. The maximum etch rate of BLT thin films was 117nm at 0.8 Ar∕(Ar+Cl2) gas mixing ratios with following conditions: process pressure of 15mTorr, gas flow rate of 20sccm, ICP power of 700W, and dc bias of −150V. The etch rate was increased as decreasing the process pressure. For a detailed investigation of etching mechanisms of BLT thin films, the ion energy distributions of each positive species were measured using Quadrupole Mass spectrometer and analyzed those data. Also the electron energy distribution was measured as a function of Ar∕Cl2 gas mixing ratios.

  • Surface etching mechanism of Bi4−xLaxTi3O12 thin films using Quadrupole Mass Spectroscopy
    Journal of Vacuum Science & Technology A: Vacuum Surfaces and Films, 2006
    Co-Authors: Jong-gyu Kim, Gwan-ha Kim, Chang-il Kim
    Abstract:

    The etching mechanism of (Bi4−xLax)Ti3O12 (BLT) thin films in Ar∕Cl2 inductively coupled plasma (ICP) was investigated as a function of gas mixing ratios, process pressure, and ICP powers at fixed other conditions. Etch rates were measured by using an α-step surface profiler. The maximum etch rate of BLT thin films was 117nm at 0.8 Ar∕(Ar+Cl2) gas mixing ratios with following conditions: process pressure of 15mTorr, gas flow rate of 20sccm, ICP power of 700W, and dc bias of −150V. The etch rate was increased as decreasing the process pressure. For a detailed investigation of etching mechanisms of BLT thin films, the ion energy distributions of each positive species were measured using Quadrupole Mass spectrometer and analyzed those data. Also the electron energy distribution was measured as a function of Ar∕Cl2 gas mixing ratios.

P. R. Willmott - One of the best experts on this subject based on the ideXlab platform.

  • Gas-phase mechanisms in the growth of ZrCyN1−y thin films by pulsed reactive crossed-beam laser ablation
    Applied Surface Science, 2002
    Co-Authors: H Spillmann, C. Clerc, Max Döbeli, P. R. Willmott
    Abstract:

    Superhard zirconium carbonitride films have been grown via pulsed reactive crossed-beam laser ablation (PRCLA) using zirconium metal and a nitrogen- and carbon-containing gas pulse mixture. The control of stoichiometry was much simplified by using the thermally stable gas-phase species N2 and CH4. The gas-phase processes are investigated using Quadrupole Mass Spectroscopy and optical emission Spectroscopy. The excitation of the ablation plume depends intimately on the collision partner of the gas pulse, in particular on its density of states and the probability of energy transfer to internal degrees of freedom.

  • Growth of SiNx and SiCx thin films by pulsed reactive crossed-beam laser ablation
    Applied Physics A: Materials Science & Processing, 2000
    Co-Authors: H Spillmann, P. R. Willmott
    Abstract:

    SiNx and SiCx films were grown on Si(001) and Si(111) using pulsed reactive crossed-beam laser ablation of Si with N2 and CH4. The scattering processes in the ablation plasma and the reactive gas pulse were investigated using time-of-flight Quadrupole Mass Spectroscopy. The film crystallinity was determined by FTIR Spectroscopy, X-ray diffraction, and reflection high-energy electron diffraction, while the stoichiometry and chemistry were investigated using XPS. SiNx was amorphous over the investigated temperature range of 25–850 °C, and x increased monotonically with temperature from 0.67 to 0.94. SiCx films grown at 850 °C consisted of oriented large β-SiC crystallites embedded in a Si matrix.

  • Reactive crossed beam scattering of a Ti plasma and a N2 pulse in a novel laser ablation method
    Journal of Applied Physics, 1997
    Co-Authors: P. R. Willmott, R. Timm, J. R. Huber
    Abstract:

    The interaction and energy transfer of a laser ablation plasma of Ti with a pulsed N2 supersonic expansion are investigated using time-of-flight Quadrupole Mass Spectroscopy and Langmuir probe techniques. The Ti ablation target and the exit nozzle of the pulsed gas source are positioned so that the plasma plume and gas pulse interact near to their respective origins, where the number density is still high, which hence results in strong coupling of the nascent plasma with the gas pulse. The timing between the gas pulse and ablation plume is shown to be critical in determining the scattering processes and the chemical nature of the films grown by this method, an example of which is presented. The degree of ionization of the plasma when crossed with the gas pulse compared to that for expansion into vacuum increases from less than 10−3 to 0.28±0.11, which is attributed to collision-induced ionization of Ti atoms. Further increasing the N2 number density quenches the ion signal. The effective bimolecular cross...

G. Betz - One of the best experts on this subject based on the ideXlab platform.

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