共查询到20条相似文献,搜索用时 15 毫秒
1.
J. Békési J.-H. Klein-Wiele P. Simon 《Applied Physics A: Materials Science & Processing》2003,76(3):355-357
The generation of submicron-sized holes on metal surfaces by applying femtosecond UV laser pulses was investigated. Different
optical schemes based on a Schwarzschild-type reflective objective were used to reach optimized ablation quality and efficiency
in different applications (hole ablation, through-hole drilling, generation of surface patterns consisting of holes, etc.).
Submicron-sized holes and hole patterns were ablated onto metal surfaces and drilled through ∼5-μm-thick steel foils with
600-nm diameter on the output side. Using a special optical interferometric method, large-area surface processing of high-conductivity
materials in the submicron regime was performed. Combining these techniques with the application of high-repetition-rate ultra-short
UV laser sources, large-area sub-μm processing of all kinds of materials in industrial environments is possible.
Received: 28 February 2002 / Accepted: 12 March 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +49-551/503599, E-mail: psimon@llg.gwdg.de 相似文献
2.
E. Millon J. Perrière R.M. Défourneau D. Défourneau O. Albert J. Etchepare 《Applied Physics A: Materials Science & Processing》2003,77(1):73-80
The elemental composition and the surface morphology of thin films grown by laser ablation of barium titanate with femtosecond
pulses at 620 nm laser wavelength have been systematically studied according to the experimental pulsed-laser deposition parameters
: laser energy density, oxygen pressure, substrate temperature, target–substrate distance and substrate position (in- and
off-axis geometry). Firstly, even at high temperature (700 °C), the deposits consist of coalesced particles up to 1-μm in
size, mixed in a poorly crystallised tetragonal BaTiO3 thin film. The particles formed in femtosecond pulsed-laser deposition induce a high surface roughness, which is observed
whatever the experimental growth conditions and does not correspond to the droplets often observed during laser ablation in
the nanosecond regime. As shown by plasma expansion dynamics, these particles propagate toward the substrate in the plasma
plume with a low velocity, and are assumed to be produced by gas-phase reactions. Moreover, the cationic concentration evaluated
through the Ba/Ti ratio strongly depends on the oxygen pressure in the ablation chamber and the angular position of the substrate
along the normal to the target at laser impact. Indeed, the films appear to be enriched in the heavy element (Ba) when the
substrate is located at high angular deviation. This fact is correlated to an increase in the lighter species (i.e. Ti) in
the central part of the plasma plume.
Received: 30 April 2002 / Accepted: 26 August 2002 / Published online: 8 January 2003
RID="*"
ID="*"Corresponding author. Fax: +33-1/4354-2878, E-mail: millon@gps.jussieu.fr
RID="**"
ID="**"Also at: LSMCL, Université de Metz, 57078 Metz Cedex 3, France 相似文献
3.
Molecular imaging by Mid-IR laser ablation mass spectrometry 总被引:1,自引:0,他引:1
Akos Vertes Peter Nemes Bindesh Shrestha Alexis A. Barton Zhaoyang Chen Yue Li 《Applied Physics A: Materials Science & Processing》2008,93(4):885-891
Mid-IR laser ablation at atmospheric pressure (AP) produces a mixture of ions, neutrals, clusters, and particles with a size
distribution extending into the nanoparticle range. Using external electric fields the ions can be extracted and sampled by
a mass spectrometer. In AP infrared (IR) matrix-assisted laser desorption ionization (MALDI) experiments, the plume was shown
to contain an appreciable proportion of ionic components that reflected the composition of the ablated target and enabled
mass spectrometric analysis. The detected ion intensities rapidly declined with increasing distance of sampling from the ablated
surface to ∼4 mm. This was rationalized in terms of ion recombination and the stopping of the plume expansion by the background
gas. In laser ablation electrospray ionization (LAESI) experiments, the ablation plume was intercepted by an electrospray.
The neutral particles in the plume were ionized by the charged droplets in the spray and enabled the detection of large molecules
(up to 66 kDa). Maximum ion production in LAESI was observed at large (∼15 mm) spray axis to ablated surface distance indicating
a radically different ion formation mechanism compared to AP IR-MALDI. The feasibility of molecular imaging by both AP IR-MALDI
and LAESI was demonstrated on targets with mock patterns.
Presented at the 9-th International Conference on Laser Ablation, 2007 Tenerife, Canary Islands, Spain 相似文献
4.
S. L. Johnson D. M. Bubb R. F. Haglund 《Applied Physics A: Materials Science & Processing》2009,96(3):627-635
We investigate the phenomenon of resonant-infrared laser ablation of polymers using polystyrene as a model material. Ablation
is carried out using various mid-IR laser wavelengths that are resonant with vibrational modes of a polystyrene target. Time-resolved
plume imaging coupled with etch-depth measurements and thermal calculations indicate that ablation begins after a superheated
surface layer reaches a temperature of ∼1000°C and undergoes spinodal decomposition. The majority of the ablated material
is then expelled by way of recoil-induced ejection as the pressure of the expanding vapor plume compresses a laser-melted
area. 相似文献
5.
M.A. Grishin H.S. Karlsson M. Månsson U.O. Karlsson 《Applied Physics A: Materials Science & Processing》2003,76(3):299-302
The conduction band electronic structure and the electron dynamics of the clean InSb(111)2×2 surface have been studied by
laser based pump-and-probe photoemission. The results are compared to earlier studies of the InSb(110) surface. It is found
that both the energy location and the time dependence of the photoexcited structures are very similar for the two surfaces.
This indicates that the dominant part of the photoemission signal in the conduction band region is due to excitations of electrons
in the bulk region and that the surface electronic states play a minor role. The fast decay of the excited state, τ∼12 ps,
indicates that diffusion of hot electrons into the bulk is an important mechanism.
Received: 9 May 2001 / Accepted: 9 July 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +46-0824/913-1, E-mail: gm@matphys.kth.se 相似文献
6.
Tatiana E. Itina Karine Gouriet Sylvie Noël Marc Sentis 《Applied Surface Science》2007,253(19):7656-7661
The mechanisms involved into the formation of clusters by pulsed laser ablation are studied both numerically and experimentally. To facilitate the model validation by comparison with experimental results, the time and length scales of the simulation are considerably increased. This increase is achieved by using a combination of molecular dynamics (MD) and the direct simulation Monte Carlo (DSMC) methods. The combined MD-DSMC model is then used to compare the relative contribution of the two channels of the cluster production by laser ablation: (i) direct cluster ejection upon the laser-material interaction, and (ii) collisional sticking and aggregation in the ablated gas flow. Calculation results demonstrate that both of these mechanisms play a role. The initial cluster ejection provides cluster precursors thus eliminating the three-body collision bottleneck in the cluster growth process. The presence of clusters thus facilitates the following collisional condensation and evaporation processes. The rates of these processes become considerable, leading to the modification of not only the plume cluster composition, but also the dynamics of the plume expansion. Calculation results explain several recent experimental findings. 相似文献
7.
8.
Silver colloids in aqueous solution were studied by different scanning microscopy techniques and UV/VIS spectroscopy. The
silver colloids were produced either by chemical reduction or by nanosecond laser ablation from a solid silver foil in water.
Variation of laser power and ablation time leads to solutions of metal clusters of different sizes in water. We characterized
the electronic absorption of the clusters by UV/VIS spectroscopy. STM (scanning tunneling microscope) imaging of the metal
colloids shows atomic resolution of rod- or tenon-like silver clusters up to 10-nm length formed by laser ablation. Our scanning
electron microscope measurements, however, show that much larger silver colloids up to 5-μm length are also formed, which
are not visible in the STM due to their roughness. We correlate them with the long-wavelength tail of the multimodal UV/VIS
spectrum. The silver colloids obtained by chemical reduction are generally larger and their electronic spectra are red-shifted
compared to the laser-ablated clusters. Irradiation of the colloid solution with nanosecond laser pulses of appropriate fluence
at 532 nm and 355 nm initially reduced the colloid size. Longer irradiation at 355 nm, however, leads to the formation of
larger colloids again. There seems to be a critical lower particle size, where silver clusters in aqueous solution become
unstable and start to coagulate.
Received: 24 June 2002 / Revised version: 25 July 2002 / Published online: 25 October 2002
RID="*"
ID="*"This work is part of the thesis of H. M?ltgen
RID="**"
ID="**"Corresponding author. Fax: +49-211/811-5195, E-mail: kleinermanns@uni-duesseldorf.de 相似文献
9.
Weisbuch F. Tokarev V.N. Lazare S. Débarre D. 《Applied Physics A: Materials Science & Processing》2003,76(4):613-620
A microscopic flow of a transient liquid film produced by KrF laser ablation is evidenced on targets of PET and PEN. Experiments
were done by using single pulses of the excimer laser beam micropatterned with the aid of submicron projection optics and
grating masks. The samples of various crystalline states, ablated with a grating-forming beam (period Λ=3.7 μm), were precisely
measured by atomic force microscopy, in order to evidence any deviation from the ablation behavior predicted by the current
theory (combination of ablation curve and beam profile). This was confirmed by comparing various behaviors dependent on the
polymer nature (PC, PET and PEN). PC is a normally ablating polymer in the sense that the ablated profile can be predicted
with previous theory neglecting liquid-flow effects. This case is called ‘dry’ ablation and PC is used as a reference material.
But, for some particular samples like crystalline PET, it is revealed that during ablation a film of transient liquid, composed
of various components, which are discussed, can flow under the transient action of the gradient of the pressure of the ablation
plume and resolidify at the border of the spot after the end of the pulse. This mechanism is further supported by a hydrodynamics
theoretical model in which a laser-induced viscosity drop and the gradient of the plume pressure play an important role. The
volume of displaced liquid increases with fluence (0.5 to 2 J/cm2) and satisfactory quantitative agreement is obtained with the present model. The same experiment done on the same PET polymer
but prepared in the amorphous state does not show microflow, and such an amorphous sample behaves like the reference PC (‘dry’
ablation). The reasons for this surprising result are discussed.
Received: 31 October 2002 / Accepted: 4 November 2002 / Published online: 22 January 2003
RID="*"
ID="*"Present address: ST Microelectronics, Crolles, France
RID="**"
ID="**"Corresponding author. Fax: +33-556/84-6645, E-mail: s.lazare@lpcm.u-bordeaux1.fr 相似文献
10.
The authors’ endeavors over the last few years with respect to boron nitride (BN) nanotube metal filling are reviewed. Mo
clusters of 1–2 nm in size and FeNi Invar alloy (Fe ∼60 at. %; Ni ∼40 at. %) or Co nanorods of 20–70 nm in diameter were embedded
into BN nanotube channels via a newly developed two-stage process, in which multi-walled C nanotubes served as templates for
the BN multi-walled nanotube synthesis. During cluster filling, low-surface-tension and melting-point Mo oxide first filled
a C nanotube through the open tube ends, followed by fragmentation of this filling into discrete clusters via O2 outflow and C→BN conversion within tubular shells at high temperature. During nanorod filling, C nanotubes containing FeNi
or Co nanoparticles at the tube tips were first synthesized by plasma-assisted chemical vapor deposition on FeNi Invar alloy
or Co substrates, respectively, and, then, the nanomaterial was heated to the melting points of the corresponding metals in
a flow of B2O3 and N2 gases. During this second stage, simultaneous filling of nanotubes with a FeNi or Co melt through capillarity and chemical
modification of C tubular shells to form BN nanotubes occurred. The synthesized nanocomposites were analyzed by scanning and
high-resolution transmission electron microscopy, electron diffraction, electron-energy-loss spectroscopy and energy-dispersive
X-ray spectroscopy. The nanostructures are presumed to function as ‘nanocables’ having conducting metallic cores (FeNi, Co,
Mo) and insulating nanotubular shields (BN) with the additional benefit of excellent environmental stability.
Received: 10 October 2002 / Accepted: 25 October 2002 / Published online: 10 March 2003
RID="*"
ID="*"Corresponding author. Fax: +81-298/51-6280, E-mail: golberg.dmitri@nims.go.jp 相似文献
11.
P.E. Dyer S.M. Maswadi C.D. Walton 《Applied Physics A: Materials Science & Processing》2003,76(5):817-822
We report an investigation of the ablation of NaCl crystals at the 157-nm wavelength of the F2 laser where there is very strong excitonic absorption. Probe-beam deflection and etch-rate measurements show that the interaction
is characterised by a low ablation threshold (∼80 mJ cm-2) and a capability for controllable material removal at the nanometer level. Scanning electron microscopy of the exposed surfaces
show this to be microscopically smooth but with fine cracks present. It is demonstrated that micron-scale features can be
formed in NaCl using 157-nm laser ablation, a result attributed to the strongly localised optical and thermal nature of the
interaction. The results are discussed within the framework of a thermal vaporisation model.
Received: 29 May 2002 / Accepted: 17 July 2002 / Published online: 4 November 2002
RID="*"
ID="*"Corresponding author. Fax: +44-1482/465606, E-mail: p.e.dyer@hull.ac.uk 相似文献
12.
A.V. Hamza M.W. Newman P.A. Thielen H.W.H. Lee T. Schenkel J.W. McDonald D.H. Schneider 《Applied Physics A: Materials Science & Processing》2003,76(3):313-317
The intense, ultra-fast electronic excitation of clean silicon (100)–(2×1) surfaces leads to the formation of silicon nanostructures
embedded in silicon, which photoluminesce in the yellow-green (∼2-eV band gap). The silicon surfaces were irradiated with
slow, highly charged ions (e.g. Xe44+ and Au53+) to produce the ultra-fast electronic excitation. The observation of excitonic features in the luminescence from these nanostructures
has recently been reported. In this paper we report the dispersion of the excitonic features with laser excitation energy.
A phonon-scattering process is proposed to explain the observed dispersion.
Received: 2 October 2001 / Accepted: 18 July 2002 / Published online: 25 October 2002
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ID="*"Corresponding author. Fax: +1-925/423-7040, E-mail: Hamza1@llnl.gov
RID="**"
ID="**"Present address: University of California, Lawrence Berkeley National Laboratory, Berkeley, CA 94 720, USA 相似文献
13.
High-resolution electron microscopy of individual metallofullerene molecules on the dipole orientations in peapods 总被引:1,自引:0,他引:1
K. Suenaga T. Okazaki K. Hirahara S. Bandow H. Kato A. Taninaka H. Shinohara S. Iijima 《Applied Physics A: Materials Science & Processing》2003,76(4):445-447
Electron microscopy with atomic sensitivity enables us to obtain a direct image of the intra-molecular structure of metallofullerenes
encapsulated inside single-walled carbon nanotubes. By a comparison of high-resolution images with a simulation to extract
the relative atom positions for encaged metal atoms in each molecule, the distribution of the molecular orientations and interactions
between adjacent molecules in metallofullerene peapods have been statistically analyzed. The results are suggestive of strong
interactions between fullerene–fullerene and fullerene–tube in peapods at room temperature.
Received: 10 October 2002 / Accepted: 25 October 2002 / Published online: 10 March 2003
RID="*"
ID="*"Corresponding author. Fax: +81-298/61-6310, E-mail: suenaga-kazu@aist.go.jp 相似文献
14.
An ultra-short-pumped optical dye amplifier operating in the near-IR (720 nm) has been developed. We present an experimental
study of the input–output characteristics of this simple device in a traveling wave collinear configuration. In essence, the
combined effects of the ultrafast nature of the anisotropy induced by the exciting laser pulse along with the short transit
time across the length of the cell allow for optimal output conditions given the number of molecules in the active volume.
Two distinct amplifying regimes have been observed depending on photon density. Typical gain values of 104 of the narrow bandwidth (∼9 nm) subpicosecond output signal were measured. The 8-mm2 beam cross section enables this photon amplifier to be utilized in time-gated imaging applications.
Received: 12 December 2001 / Revised version: 13 May 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +1-819/564-5442, E-mail: Daniel.Houde@Usherbrooke.ca 相似文献
15.
16.
F.C. Fonseca G.F. Goya R.F. Jardim N.L.V. Carreño E. Longo E.R. Leite R. Muccillo 《Applied Physics A: Materials Science & Processing》2003,76(4):621-623
Ni nanoparticles embedded in an amorphous SiO2 matrix were produced by a modified sol–gel method. This method resulted in nanocomposites with a controlled size distribution
and good dispersion of the metallic particles. The particle-size distributions were found to have an average radius of ∼3 nm,
as inferred from transmission electron microscopy, X-ray-diffraction analysis, and magnetic measurements. Magnetic characterizations
revealed that samples exhibit superparamagnetic behavior above the blocking temperature TB, 20 K≤TB≤40 K, and absence of a shift along the field axis on hysteresis loops measured at T≤TB, indicating that the metallic nanoparticles are also free from an oxide layer.
Received: 7 October 2002 / Accepted: 9 October 2002 / Published online: 8 January 2003
RID="*"
ID="*"Corresponding author. Fax: +55-11/3091-6984, E-mail: rjardim@if.usp.br 相似文献
17.
Excimer laser polymer ablation: twenty years on 总被引:7,自引:0,他引:7
P.E. Dyer 《Applied Physics A: Materials Science & Processing》2003,77(2):167-173
Research and development in excimer laser polymer ablation has been actively pursued for some twenty years, driven by interest
in the basic science as well as by numerous applications that have emerged for this high-resolution technique for material
removal. This paper reviews some of the basic mechanistic aspects of the UV laser–polymer interaction as a prelude to dealing
with practical matters related to polymer processing by ablation. Applications in micro-machining and potential areas for
future research are briefly covered.
Received: 7 October 2002 / Accepted: 8 February 2003 / Published online: 28 May 2003
RID="*"
ID="*"Corresponding author. Fax: +44-1482/465-606, E-mail: p.e.dyer@hull.ac.uk 相似文献
18.
W.Y. Wang D.F. Zhang T. Xu Y.P. Xu T. Zhou B.Q. Hu C.Y. Wang L.S. Wu X.L. Chen 《Applied Physics A: Materials Science & Processing》2003,76(1):71-75
Ca,Ta-doped TiO2 varistors with high nonlinear coefficients are obtained by a ceramic sintering. The nonlinear electrical and dielectric properties
of the samples doped with 0.5mol% Ca and various concentrations of Ta (0.05∼2.0mol%) were investigated. The samples sintered
at 1350 °C have nonlinear coefficients of α=5.1∼42.1 and high relative dielectric constants approach 105. The effects of Ta-doping on the nonlinear and dielectric properties of the Ca,Ta-doped TiO2 varistors are studied in greater detail. When the concentration of Ta is 0.5mol%, the sample possesses the highest nonlinear
coefficient and a comparatively lower dielectric constant. The effects of Ta and the nonlinear electrical behavior of the
TiO2 system are explained by analogy to a grain-boundary atomic defect model.
Received: 24 October 2001 / Accepted: 8 January 2002 / Published online: 3 May 2002
RID="*"
ID="*"Corresponding author. Fax: +86-10/826-49531, E-mail: wangwanyan@yahoo.com.cn 相似文献
19.
A. Camposeo F. Fuso E. Arimondo A. Tuissi 《Applied Physics A: Materials Science & Processing》2003,76(6):927-934
NiTi films deposited by pulsed laser ablation on Si/SiO2 are shown to exhibit structural and functional properties related to the shape-memory effect. Film characterization suggests
that relevant temperatures for the solid-to-solid transformation responsible for the shape memory are in substantial agreement
with those of the bulk target material, demonstrating a good congruency of the deposition process. Besides the technological
interest for this class of thin films, our findings point out the suitability of laser ablation for metal alloy deposition.
An investigation based on in situ ion-mass spectroscopy and covariance mapping analysis allows us to determine the main vapor-phase
processes leading to the formation of stoichiometric clusters expected to play a relevant role in assisting the growth of
NiTi thin films.
Received: 6 August 2001 / Accepted: 11 April 2002 / Published online: 4 November 2002
RID="*"
ID="*"Corresponding author. Fax: +39-50/2214-333, E-mail: fuso@df.unipi.it 相似文献
20.
Surface nanostructuring of silicon 总被引:1,自引:0,他引:1
A.J. Pedraza J.D. Fowlkes Y.-F. Guan 《Applied Physics A: Materials Science & Processing》2003,77(2):277-284
Irradiation with polarized laser light of 248-nm wavelength induces the formation of periodic undulations ∼10-nm-highon flat
silicon substrates. The wavelength of these periodic structures is a function of the light wavelength and the angle of incidence
of the laser beam. Linear arrays of silicon nanoparticles with fairly uniform size that extended up to a millimeter were formed
if the irradiation was performed using polarized light. When non-polarized laser light with the same fluence was used to illuminate
an initially flat surface, non-aligned nanoparticle strings were obtained. However, if part of the irradiated area was microstructured,
nanoparticle linear arrays resulted in the vicinity of the microstructured region. An analysis on the evolution of these nanostructures
is presented. Nanocolumns could be grown on top of every cone of a microstructured surface upon cumulative laser irradiation
with non-polarized light, reaching a height of ∼3 μm and a diameter of 100–200 nm. The mechanisms of nanocolumn origin and
growth are analyzed.
Received: 16 December 2002 / Accepted: 20 January 2003 / Published online: 28 May 2003
RID="*"
ID="*"Corresponding author. Fax: +1-865/974-4115, E-mail: apedraza@utk.edu 相似文献