共查询到20条相似文献,搜索用时 26 毫秒
1.
T.V. Kononenko S.V. Garnov S.M. Pimenov V.I. Konov V. Romano B. Borsos H.P. Weber 《Applied Physics A: Materials Science & Processing》2000,71(6):627-631
Laser ablation of thin TiN films deposited on steel substrates has been studied under wide-range variation of irradiation
conditions (pulsewidth, wavelength, energy density and spot size). It has been demonstrated that both picosecond (150–300 ps)
and nanosecond (5–9 ns) laser pulses were suitable for controllable ablation and microstructuring of a 1-μm-thick TiN film
unlike longer 150-ns pulses. The ablation rate was found to be practically independent of the wavelength (270–1078 nm) and
pulsewidth (150 ps–9 ns), but it increased substantially when the size of a laser spot was reduced from 15–60 μm to 3 μm.
The laser ablation technique was applied to produce microstructures in the thin TiN films consisting of microcraters with
a typical size of 3–5 μm in diameter and depth less than 1 μm. Tests of lubricated sliding of the laser-structured TiN films
against a steel ball showed that the durability of lubricated sliding increased by 25% as compared to that of the original
TiN film.
Received: 28 July 1999 / Accepted: 17 April 2000 / Published online: 20 September 2000 相似文献
2.
3 ) at wavelengths ranging from the ultraviolet to the mid-infrared, including a Nd:YAG laser operated at the fundamental, second
and third harmonics, and a tunable infrared free-electron laser (wavelength range 2.5–8 μm). The threshold for ablation and
the topography of the irradiated spot were characterized by scanning electron microscopy. A clear indication of two distinct
excitation mechanisms was observed, namely, cracks and fractures followed by exfoliation at ultraviolet to near-infrared wavelengths,
in contrast to evaporative holes and scattered droplets in the mid-infrared. Plume emission/absorption spectroscopy, plume
transmission and photoacoustic beam deflection were used to characterize the ablation plasma. The composition of atoms, molecules,
or particles in the ablation plumes also has a distinctive variation as a function of the wavelength. The excitation mechanisms
leading to ablation appear to be defect activation at ultraviolet to near-infrared wavelengths, molecular impurity absorption
and resonant vibrational absorption of the calcite at mid-infrared.
Received: 5 December 1996/Accepted: 6 January 1997 相似文献
3.
Resonant infrared femtosecond light pulses in the 3 μm region are used to excite specific CH-stretching modes of liquid 1,1,1-trichloroethane,
cyclopentane, and cyclohexane. The ultrafast redistribution of vibrational excitation between different CH-stretching modes
and the vibrational relaxation of these modes are monitored by spontaneous anti-Stokes Raman scattering of properly delayed
and spectrally shaped probe pulses. The results are treated with a rate-equation system, yielding energy-redistribution and
energy-relaxation times.
Received: 16 December 1999 / Published online: 7 August 2000 相似文献
4.
P.W. Leech A.S. Holland S. Sriram M. Bhaskaran 《Applied Physics A: Materials Science & Processing》2008,91(4):679-684
The patterning of lanthanum-doped lead zirconate titanate (PLZT) and strontium-doped lead zirconate titanate (PSZT) thin films
has been examined using a 5-ns pulsed excimer laser. Both types of film were deposited by rf magnetron sputtering with in
situ heating and a controlled cooling rate in order to obtain the perovskite-structured films. The depth of laser ablation
in both PSZT and PLZT films showed a logarithmic dependence on fluence. The ablation rate of PLZT films was slightly higher
than that of PSZT films over the range of fluence (10–150 J/cm2) and increased linearly with number of pulses. The threshold fluence required to initiate ablation was ∼ 1.25 J/cm2 for PLZT and ∼ 1.87 J/cm2 for PSZT films. Individual squares were patterned with areas ranging from 10×10 μm2 up to 30×30 μm2 using single and multiple pulses. The morphology of the etched surfaces comprised globules which had diameters of 200–250 nm
in PLZT and 1400 nm in PSZT films. The diameter of the globules has been shown to increase with fluence until reaching an
approximately constant size at ≤ 20 J/cm2 in both types of film. The composition of the films following ablation has been compared using X-ray photoelectron spectroscopy
and energy-dispersive X-ray spectroscopy.
PACS 79.20.Ds; 82.80.Pv; 82.80.Ej 相似文献
5.
D.M. Bubb B. Toftmann R.F. Haglund Jr. J.S. Horwitz M.R. Papantonakis R.A. McGill P.W. Wu D.B. Chrisey 《Applied Physics A: Materials Science & Processing》2002,74(1):123-125
Thin films of the biodegradable polymer poly(DL-lactide-co-glycolide) (PLGA) were deposited using resonant infrared pulsed
laser deposition (RIR-PLD). The output of a free-electron laser was focused onto a solid target of the polymer, and the films
were deposited using 2.90 (resonant with O-H stretch) and 3.40 (C-H) μm light at macropulse fluences of 7.8 and 6.7 J/cm2, respectively. Under these conditions, a 0.5-μm thick film can be grown in less than 5 min. Film structure was determined
from infrared absorbance measurements and gel permeation chromatography (GPC). While the infrared absorbance spectrum of the
films is nearly identical with that of the native polymer, the average molecular weight of the films is a little less than
half that of the starting material. Potential strategies for defeating this mass change are discussed.
Received: 22 August 2001 / Accepted: 23 August 2001 / Published online: 17 October 2001 相似文献
6.
The availability of tunable, picosecond free-electron lasers operating with high efficiency in the mid-infrared opens a materials-processing regime qualitatively distinct from that accessed by femtosecond Ti:sapphire lasers, one which is characterized by a high spatio-temporal density of vibrational, rather than electronic, excitation. As an example of this novel materials-processing regime, we present new results on pulsed laser deposition of thin poly(tetrafluoroethylene) films. Films of poly(tetrafluoroethylene) were deposited by resonant (4.2 and 8.26 m) and non-resonant (7.1 m) infrared picosecond laser ablation from either a pressed powder target or a commercial bulk target. The films were smooth and crystalline and largely free of particulates without annealing. Infrared and X-ray photoelectron spectra indicated that the films retained the chemical properties of the starting material. Observations of the film properties are consistent with a steady-state ablation mechanism, possibly enhanced by non-linear absorption due to the high photon flux in the free-electron laser micropulses. PACS 81.05.Lg; 69.37.-d; 81.15.Fg 相似文献
7.
F. Kokai M. Taniwaki M. Ishihara Y. Koga 《Applied Physics A: Materials Science & Processing》2002,74(4):533-536
We deposited amorphous thin films of boron carbide by pulsed laser deposition using a B4C target at room temperature. As the laser fluence increased from 1 to 3 J/cm2, the number of 0.25–5 μm particulates embedded in the films decreased, and the B/C atomic ratio of the films increased from
1.8 to 3.2. The arrival of melt droplets, atoms, and small molecular species depending on laser fluence appeared to be involved
in the film formation. In addition, with increasing fluence the nanoindentation hardness of the films increased from 14 to
32 GPa. We believe that the dominant factor in the observed increase in the films’ hardness is the arrival of highly energetic
ions and atoms that results in the formation of denser films.
Received: 23 March 2001 / Accepted: 1 July 2001 / Published online: 2 October 2001 相似文献
8.
A photo-chemical vapor deposition, using ultraviolet light excitation and a mercury photo-sensitization, was investigated for depositing hydrogenated amorphous silicon films from SiH4. The photoelectric and structural properties were examined to characterize the deposited films. Those properties were depended strongly on substrate temperature, and the films which were deposited at a substrate temperature more than 200°C contained dominant SiH configurations. A relatively large single crystalline grain size of about 0.5 m was observed in a 1.0 m thick film, which was obtained at a substrate temperature as low as 200°C. Phosphorus impurity doping into the films and Pt-Schottky diode fabrication were also attempted. 相似文献
9.
Laksminarayana Rao Naveen Krishna Reddy Sylvain Coulombe Jean-Luc Meunier Richard J. Munz 《Journal of nanoparticle research》2007,9(4):689-695
This communication reports on a new method for the collection of nanoparticles using carbon nanotubes (CNT) as collecting
surfaces, by which the problem of agglomeration of nanoparticles can be circumvented. CNT (10–50 nm in diameter, 1–10 μm in
length) were grown by thermal CVD at 923 K in a 7 v/v% C2H2 in N2 mixture on electroless nickel-plated copper transmission electron microscopy (TEM) grids and Monel coupons. These samples
were then placed downstream of an arc plasma reactor to collect individual copper nanoparticles (5–30 nm in diameter). It
was observed that the Cu nanoparticles preferentially adhere onto CNT and that the macro-particles (diameter >1 μm), a usual
co-product obtained with metal nanoparticles in the arc plasma synthesis, are not collected. Cu–Ni nanoparticles, a catalyst
for CNT growth, were deposited on CNT to grow multibranched CNT. CNT-embedded thin films were produced by re-melting the deposited
nanoparticles. 相似文献
10.
A. Weller F.C. Liu R. Dahint M. Himmelhaus 《Applied physics. B, Lasers and optics》2008,90(3-4):561-567
Whispering gallery modes (WGM) of dye-doped polystyrene beads with diameters from 20 down to 1.5 μm are studied with respect
to their appearance and linewidth by excitation of the entire mode spectrum within the emission range of the dye. The lowest
order (q=1) modes, which travel most closely to the inner particle surface, are assigned to their individual quantum numbers
by means of a least-square-fit, resulting in a precise determination of particle radius and eccentricity. On this basis, the
suitability of these microscopic cavities for applications in optical (bio-)sensing is explored. Due to the low quality (Q)
factors of these small cavities, particles with diameters below 6 μm exhibit only q=1 modes, thereby causing a drastic simplification
of the WGM spectrum. In such spectra, the shift in the WGM positions upon molecular adsorption can be easily monitored, as
we demonstrate for the adsorption of bovine serum albumin as well as multiple layers of polyelectrolytes onto the surface
of particles with 2 μm diameter. Mie simulations are used to confirm our findings. With a mass sensitivity limit of 3 fg,
these microscopic sensors are highly competitive in the field of label-free detection techniques. Moreover, their small size
and the simplified, dye-mediated excitation and detection scheme may pave the way to remote in-vitro biosensing in the future.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.
PACS 07.07.Df; 42.60.Da; 42.70.Jk 相似文献
11.
D. Auernhammer M. Schmitt M. Ohtsuka M. Kohl 《The European physical journal. Special topics》2008,158(1):249-254
The technologies of electron beam lithography, dry
etching and systems integration are investigated to fabricate a series of
Ni-Mn-Ga double-beam structures designed with decreasing critical dimensions
of 10 μm, 1 μm and 400 nm. Ni-Mn-Ga thin films of 1 μm
thickness are deposited by magnetron sputtering and heat-treated in
free-standing condition after selective removal of the substrate.
Differential scanning calorimetry and electrical resistance measurements on
the films show the characteristic features of martensitic transformation
above room temperature. First optical beam deflection experiments
demonstrate the magnetic and thermal actuation performance of the
double-beam structures. 相似文献
12.
Alexios Papadimitratos Aram Amassian Aravind S. Killampalli Jared L. Mack George G. Malliaras James R. Engstrom 《Applied Physics A: Materials Science & Processing》2009,95(1):29-35
Top-contact organic thin-film transistors (OTFTs) of pentacene have been fabricated on bare SiO2 and SiO2 modified with hexamethyldisilazane (HMDS) and octadecyltrichlorosilane (OTS). The pentacene films were deposited from a supersonic
molecular beam source with kinetic energy of incident molecules ranging from 1.5 to 6.7 eV. The field-effect mobility of OTFTs
was found to increase systematically with increasing kinetic energy of the molecular beam. The improvements are more important
on HMDS- and OTS-treated surfaces than on bare SiO2. Tapping mode atomic force microscopy images reveal that pentacene thin films deposited at high kinetic energy form with
significantly larger grains—independent of surface treatment—than films deposited using low-energy beams. 相似文献
13.
V. O. Kompanets V. B. Laptev A. A. Makarov S. V. Pigulsky E. A. Ryabov S. V. Chekalin 《JETP Letters》2010,92(3):135-139
The dynamics of multiphoton excitation of (CF3)2CCO molecules has been investigated under the condition of resonant action of femtosecond infrared laser radiation on the
ν1 vibrational mode of the C=C=O bond. It has been shown that the mode-selective excitation of this vibration occurs up to the
ν = 6 level. The kinetics of the subsequent intramolecular vibrational energy redistribution from the ν1 mode has been measured. A value of 5 ± 0.3 ps has been obtained for the characteristic time of this process. 相似文献
14.
L. Cultrera A. Dima A. Perrone D. Pisignano R. Cingolani A. Klini 《Applied Physics A: Materials Science & Processing》2007,88(2):435-438
The angular distribution of the ablated material was studied during sub-ps Si laser ablation deposition using a special hemicylindrical
substrate holder and different laser fluences ranging between 0.4 and 1.7 J/cm2. Scanning electron microscopy analysis of the deposited films showed that, independent of the fluence, the distribution of
the deposited droplets presents two maxima. The first maximum corresponds to the average plume deflection angle value due
to the local surface orientation produced by the preferential etching process. The second maximum is observed approximately
at 45° with respect to the normal of the target surface, and is related to the phase explosion products that expand along
the incident laser beam direction. The investigation of the twofold distribution of the sub-μm size deposited droplets is
important to improve the quality of the deposited coatings.
PACS 81.15.Fg; 68.55.Jk; 79.20.Ds 相似文献
15.
M. Schiffer M. Rauner S. Kuppens M. Zinner K. Sengstock W. Ertmer 《Applied physics. B, Lasers and optics》1998,67(6):705-708
01
* (doughnut) modes for atomic beam manipulation. A slow atomic beam is guided over up to 0.3 m and focused down to 6.5 μm radius.
The doughnut mode is used as a strong mesoscopic dipole potential with vibrational level spacings up to the photon recoil
energy. Polarization gradient cooling in this system generates a bimodal momentum distribution with a narrow component momentum
width of 4 ?k.
Received: 26 June 1998 相似文献
16.
《Ultrasonics》2014,54(6):1504-1508
We describe the fabrication and frequency characterization of different structures intended for the lateral excitation of shear modes in AlN c-axis-oriented films. AlN films are deposited on moderately doped silicon substrates covered either with partially metallic or fully insulating Bragg mirrors, and on insulating glass plates covered with insulating acoustic reflectors. TiOx seed layers are used to promote the growth of highly c-axis oriented AlN films, which is confirmed by XRD and SAW measurements. The excitation of the resonant modes is achieved through coplanar Mo electrodes of different geometries defined on top of the AlN films. All the structures analyzed display a clear longitudinal mode travelling at 11,000 m/s, whose excitation is attributed to the direction of the electric field (parallel to the c-axis) below the electrodes; this is enhanced when a conductive plane (metallic layer or Si substrate) is present under the piezoelectric layer. Conversely, only a weak shear resonance (6,350 m/s) is stimulated through the effect of coplanar electrodes, which is explained by the weakness of the electric field strength parallel to the surface between the electrodes. A significantly more effective excitation of shear modes can be achieved by normal excitation of AlN films with tilted c-axis. 相似文献
17.
Sk.F. Ahmed P.K. Ghosh S. Khan M.K. Mitra K.K. Chattopadhyay 《Applied Physics A: Materials Science & Processing》2007,86(1):139-143
We have observed low-macroscopic field electron emission from wide bandgap nanocrystalline Al doped SnO2 thin films deposited on glass substrates. The emission properties have been studied for different anode-sample spacings and for different Al concentrations in the films. The turn-on field and approximate work function were calculated and we have tried to explain the emission mechanism from this. The turn-on field was found to vary in the range 5.6–7.5 V/μm for a variation of anode sample spacing from 80–120 μm. The turn-on field was also found to vary from 4.6–5.68 V/μm for a fixed anode-sample separation of 80 μm with a variation of Al concentration in the films 8.16–2.31%. The Al concentrations in the films have been measured by energy dispersive X-ray analysis. Optical transmittance measurement of the films showed a high transparency with a direct bandgap ∼3.98 eV. Due to the wide bandgap, the electron affinity of the film decreased. This, along with the nanocrystalline nature of the films, enhanced the field emission properties. PACS 81.20.Fw; 61.10.-i; 79.70.+q 相似文献
18.
The structures of the molecular propolis films deposited from an alcohol solution on the (0001) cleavage surface of layered
bismuth selenide and telluride are studied by X-ray diffraction. Despite the chemical interaction between the semiconductor
substrates and the organic-substance components, the molecular structural ordering of the propolis films is shown to be identical
to that in the films of this substance on the surface of amorphous glass substrates. The chemical and deformation interaction
between the organic substance and the layered V2VI3 compounds is found to result in the formation of an organic-inorganic sandwich nanostructure at a distance of ∼0.3 μm from
the layered crystal-propolis film interface. 相似文献
19.
M. Jelinek J. Lančok M. Pavelka P.A. Atanasov A. Macková F. Flory C. Garapon 《Applied Physics A: Materials Science & Processing》2002,74(4):481-485
Nd: KGd(WO4)2 thin films were deposited by KrF laser ablation on MgO, YAP, YAG and Si substrates at temperatures up to 800 °C. Film crystallinity,
morphology, stoichiometry (WDX, RBS and PIXE), excitation spectra, fluorescence, refractive index and waveguiding properties
were studied in connection with deposition conditions. The best films were crystalline and exhibited losses of approximately
5 dB cm-1 at a wavelength of 633 nm.
Received: 8 January 2001 / Accepted: 7 November 2001 / Published online: 11 February 2002 相似文献
20.
P. Frank J. Graf F. Lang J. Boneberg P. Leiderer 《Applied Physics A: Materials Science & Processing》2010,101(1):7-11
The ejection dynamics of nanometer-thin fluid isopropanol and solid CO2 films are investigated. The films are deposited on a silicon substrate, which is rapidly heated by a nanosecond laser pulse
(Nd:YAG, 532 nm). A small fraction of material at the interface evaporates and the film on top is ejected as an intact layer.
The kinetic energies of the two different films with thicknesses between 100 nm and 1 μm give an insight into the dynamics
of a flying lamella. 相似文献