共查询到20条相似文献,搜索用时 31 毫秒
1.
D. Guo K. Cai Y. Huang L.-T. Li 《Applied Physics A: Materials Science & Processing》2003,76(7):1121-1124
This work reports a novel anti-spatter and anti-crack ceramic laser drilling method based on the gelcasting technique. A Nd:YAG
solid state laser was used to drill micro-holes directly on a gelcast green alumina body. The results reveal that the irregular
spatter at the periphery of the hole inherent to traditional laser drilling methods can be effectively prevented by direct
drilling of the gelcast green body. Much more regular hole shapes without microcracks were also successfully obtained.
Received: 02 October 2002 / Accepted: 07 October 2002 / Published online: 22 January 2003
RID="*"
ID="*"Corresponding author. Fax: +86-10-62771160, E-mail: caikai99@mails.tsinghua.edu.cn 相似文献
2.
We describe the measurement of the line width of an atom laser beam extracted from a Bose–Einstein condensate. Using a novel
magnetic resonance imaging technique, we find that the energy width of the atom laser beam is Fourier-limited by the duration
of the output-coupling process.
Received: 25 July 2002 / Revised version: 28 October 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax: +41-1/633-1254, E-mail: koehl@iqe.phys.ethz.ch 相似文献
3.
A model is derived linking microdroplet emission of a liquid-metal ion source (LMIS) to the actual current–voltage characteristic
and operating temperature. All parameters were experimentally investigated using an indium LMIS, confirming the relationships
found. The model allows for the first time the optimisation of a LMIS for low droplet emission at high emission currents.
This is very important for application as a thruster, which has been developed at ARC Seibersdorf research. It can be also
used to extrapolate droplet emission values along the current–voltage characteristic.
Received: 29 January 2002 / Accepted: 7 October 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: +43-50550/3366, E-mail: martin.tajmar@arcs.ac.at 相似文献
4.
Transmission electron microscopy studies of femtosecond laser induced modifications in quartz 总被引:1,自引:0,他引:1
T. Gorelik M. Will S. Nolte A. Tuennermann U. Glatzel 《Applied Physics A: Materials Science & Processing》2003,76(3):309-311
Cross-sectional transmission electron microscopy investigations of femtosecond laser induced sub-micrometer structural modifications
inside crystalline quartz were carried out. Modifications from single laser shots and from lines built of overlapping shots
were imaged. Both single laser shot modifications and line structures show an amorphous core surrounded by a disturbed crystalline
structure. A strong strain field surrounding the central, irradiated, core is responsible for an increase of the refractive
index. Finite element method calculations of the strain field show maxima on both sides of the irradiated core, which are
in good agreement with optical measurements of the refractive-index change.
Received: 29 September 2001 / Accepted: 9 July 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +49-3641/947792, E-mail: tatiana.gorelik@rz.uni-jena.de 相似文献
5.
Strong blue photoluminescence from aligned silica nanofibers 总被引:1,自引:0,他引:1
L. Dai X.L. Chen J.K. Jian W.J. Wang T. Zhou B.Q. Hu 《Applied Physics A: Materials Science & Processing》2003,76(4):625-627
Photoluminescence (PL) and infrared spectra of aligned silica nanofibers are investigated. Two striking strong blue luminescence
emissions have been found at room temperature. This suggests that the silica nanofibers could be a candidate material for
a blue-light emitter. The intensity of the PL emission decreases after annealing, which can be interpreted as the decrease
of the oxygen deficiency resulting in the reduction of radiative recombination centers. Infrared spectra provide further evidence
of this conclusion, where the enhancement of Si–O absorption is observed in annealed samples.
Received: 2 October 2002 / Accepted: 7 October 2002 / Published online: 8 January 2003
RID="*"
ID="*"Corresponding author. Fax: +86-10/8264-9531, E-mail: ldai@vip.sina.com 相似文献
6.
U. Hübner W. Morgenroth H.G. Meyer T. Sulzbach B. Brendel W. Mirandé 《Applied Physics A: Materials Science & Processing》2003,76(6):913-917
More and more AFMs and AFM profilers will be used to quantify micro- and nanostructures. For a correct characterization and
evaluation of the measured structural details, in the nanoscale range, knowledge of the current shape of the AFM tip is needed.
Often, the interaction between the AFM tip and the sample leads to a change in the tip shape. Our concept for the determination
of tip shapes is based on the measurement of a well-known sharp-edged silicon structure. Each calibration sample contains
a selected structure serving as a calibrated width standard, and has a certified pitch. Consequently, the shape of AFM tips
can be determined with an accuracy of 10 nm.
Received: 2 September 2002 / Accepted: 2 September 2002 / Published online: 5 March 2003
RID="*"
ID="*"Corresponding author. Fax: +49-3641/206-199, E-mail: huebner@ipht-jena.de 相似文献
7.
J.S. Gibb G. Hancock A. Hutchinson R. Peverall G.A.D. Ritchie 《Applied physics. B, Lasers and optics》2003,76(1):97-105
A simple technique is demonstrated for the accurate determination of pressure-induced line shifts of water in air. High- and
low-pressure water samples are simultaneously probed on selected overtone transitions at 1.32 μm using a current-modulated
distributed-feedback diode laser and harmonic detection. The resultant profiles yield an average line shift of -293±30 MHz/atm
for the 3,3,0 (002)2,2,1 (000)transition at 227251 GHz and -134±7 MHz/atm for the 3,2,1 (002)2,1,2 (000) transition at 227027 GHz.
Comparisons are made between first- and second-harmonic detection, and wavelength- and frequency-modulation regimes. The effect
of modulation broadening on the returned line shifts is quantified.
Received: 12 August 2002 / Revised version: 21 October 2002 / Published online: 8 January 2003
RID="*"
ID="*"Corresponding author. Fax: +44-01865/275410, E-mail: gus.hancock@chemistry.ox.ac.uk 相似文献
8.
The backscattered fluorescence of nitrogen from filaments generated by intense ultra-fast Ti:sapphire laser pulses propagating
in air is studied. The backscattered fluorescence from N2 molecules and ions show an exponential increase with increasing filament length, indicating amplified spontaneous emission.
Received: 11 October 2002 / Revised version: 3 December 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax: +1-418/6562-623, E-mail: qluo@phy.ulaval.ca 相似文献
9.
The use of mid-infrared polarization spectroscopy (PS) for the detection of CO2 has been demonstrated. The P(13) and P(14) resonances of the (0 00 0)→(1 00 1) transition of CO2 were probed using a single-mode optical parametric generator system to produce a high-intensity laser beam at approximately
2.7 μm. The experiments were performed in an atmospheric pressure CO2 jet and also in a sub-atmospheric pressure gas cell. The experimental results were compared with the results of the time-dependent
density-matrix equations using direct numerical integration. The Zeeman-state structure of the upper and lower energy levels
was included in the multi-state formulation of the density-matrix equations. Fifty-eight Zeeman states and two bath levels
were included in the numerical analysis of the P(14) transition. The measured and calculated PS line shapes were in good agreement,
and the absolute experimental signal level agreed with the theoretical calculation to within a factor of five.
Received: 20 March 2002 / Revised version: 16 August 2002 / Published online: 11 December 2002
RID="*"
ID="*"Present address: Innovative Scientific Solutions Inc., 2766 Indian Ripple Road, Dayton, OH 45 440, USA
RID="**"
ID="**"Corresponding author. Fax: +1-765/494-0539, E-mail: Lucht@purdue.edu
RID="***"
ID="***"Present address: School of Mechanical Engineering, Purdue University, W. Lafayette, IN 47807-2040 USA 相似文献
10.
A. Iwasaki N. Aközbek B. Ferland Q. Luo G. Roy C.M. Bowden S.L. Chin 《Applied physics. B, Lasers and optics》2003,76(3):231-236
We demonstrate a new method for measuring the length of a femtosecond laser pulse induced filament in air using a LIDAR (LIght
Detection And Ranging) technique. The LIDAR involves a detector with a fast response time. The back-scattered multiphoton
induced fluorescence from nitrogen molecules excited inside the filament is measured, from which the length of the filament
can be determined. We find good agreement between the measured filament length and the length estimated from burn patterns
on paper. In addition, good qualitative agreement between the experimental measurement and numerical simulations is obtained
for the signal features of the filament. We propose that this new method can be used to quantitatively determine filamentation
at longer distances.
Received: 11 June 2002 / Revised version: 21 October 2002 / Published online: 5 February 2003
RID="*"
ID="*"Corresponding author. Fax: +1-418/656-2623, E-mail: aiwasaki@phy.ulaval.ca 相似文献
11.
J. Botero M.A. Cirone J.P. Dahl F. Straub W.P. Schleich 《Applied physics. B, Lasers and optics》2003,76(2):129-133
We express the commutation relation between the operators of the momentum and the radial unit vectors in D dimensions in differential
and integral form. We connect this commutator with the quantum fictitious potential emerging in the radial Schr?dinger equation
of an s-wave.
Received: 6 August 2002 / Revised version: 30 October 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax: +49-731/502-3086, E-mail: markus.cirone@physik.uni-ulm.de 相似文献
12.
V.V. Belov 《Applied physics. B, Lasers and optics》2002,75(4-5):571-576
Characteristics of object images observed through scattering media with an active vision system operating in the mode of spatial
selection are estimated using the Monte Carlo method. The effect of optical and geometrical conditions of observation on the
contrast in images of reflecting objects is considered. Interpretation is given to the obtained dependences.
Received: 11 February 2002 / Revised version: 31 May 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +7-38/2225-9086, E-mail: belov@iao.ru 相似文献
13.
Studies of nanocluster coalescence at high temperature 总被引:1,自引:0,他引:1
H.B. Liu M. José-Yacaman R. Perez J.A. Ascencio 《Applied Physics A: Materials Science & Processing》2003,77(1):63-67
Molecular Dynamics simulations and high resolution electron microscope observations were used to determine the mechanism of
nanocluster coalescence in detail. In the simulations, the tight-binding second momentum approximation potential was used
to describe the interatomic interactions. The calculations not only reproduced the experimentally observed translation and
reorientation during the coalescing process, but also made it possible to determine the time scale of each step in the process
and to observe details of the process that could not be obtained from the experiment. For high temperature coalescence, a
new mechanism differing from classical theory is proposed.
Received: 14 October 2002 / Accepted: 16 October 2002 / Published online: 28 March 2003
RID="*"
ID="*"Corresponding author. Fax: +52-55/3003-6414, E-mail: ascencio@imp.mx 相似文献
14.
C. Westphal 《Applied Physics A: Materials Science & Processing》2003,76(5):721-730
Angle- and energy-scanned photoelectron diffraction data can be used to investigate structures below surfaces. The modulations
in photoelectron intensity result from diffraction of the emitted electron wave at neighbor atoms. In the past, scanned-energy
photoelectron diffraction had been mainly used to determine the adsorption site of molecules at surfaces. Recent data show,
however, that the technique can also be employed to obtain information about the upper substrate layer(s). At low kinetic
energies, backward scattering is strong and in scanned-angle photoelectron diffraction the recorded patterns result from backward-
and multiple-scattering effects. For a structural analysis, the intensity modulations have to be compared with the results
for simulations performed for model clusters. As an example, recent angle-scanned photoelectron diffraction patterns recorded
for the technologically important silicon oxide/silicon interface were compared with simulations. At the Si(001) surface orientation,
the interface is extended over a few layers, whereas at the Si(111) surface orientation the transition is rather abrupt and
occurs within one or two layers.
Received: 9 September 2002 / Accepted: 2 October 2002 / Published online: 5 February 2003
RID="*"
ID="*"Corresponding author. Fax: +49-231/755-3657, E-mail: carsten.westphal@physik.uni-dortmund.de 相似文献
15.
Random deflection of the white light beam during self-focusing and filamentation of a femtosecond laser pulse in water 总被引:1,自引:0,他引:1
W. Liu O. Kosareva I.S. Golubtsov A. Iwasaki A. Becker V.P. Kandidov S.L. Chin 《Applied physics. B, Lasers and optics》2002,75(4-5):595-599
Ti:sapphire femtosecond laser pulse filamentation in competition with optical breakdown in condensed matter is studied both
experimentally and numerically using water as an example. Strong random deflection and modulation of the supercontinuum under
tight focusing conditions were observed. They manifest the beginning of the filamentation process near the highly disordered
plasma created by optical breakdown at the geometrical focus.
Received: 13 June 2002 / Revised version: 16 August 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +1-418/656-2623, E-mail: wliu@phy.ulaval.ca 相似文献
16.
J. Magyar C. Aita M. Gajdardziska-Josifovska A. Sklyarov K. Mikhaylichenko V.V. Yakovlev 《Applied Physics A: Materials Science & Processing》2003,77(2):285-291
We use short-pulse high-power lasers to selectively modify the structure of nanolaminates and nanocrystals. It is demonstrated
that femtosecond pulses can achieve excellent results for microscopic thin film removal. Laser pulses can also be used to
modify the crystal structure of thin films. It is also demonstrated that coherent laser excitation promotes a selective modification
of nanocrystals, resulting in changes of size, shape, and crystal structure.
Received: 7 October 2002 / Accepted: 20 January 2003 / Published online: 28 May 2003
RID="*"
ID="*"Corresponding author. Fax: +1-414/229-5589, E-mail: yakovlev@uwm.edu 相似文献
17.
100-W average-power, high-energy nanosecond fiber amplifier 总被引:5,自引:0,他引:5
J. Limpert S. Höfer A. Liem H. Zellmer A. Tünnermann S. Knoke H. Voelckel 《Applied physics. B, Lasers and optics》2002,75(4-5):477-479
We report on the fiber-based amplification of a Q-switched Nd:YAG thin-disk laser. At repetition rates between 3 and 50 kHz
output powers up to 100 W are generated. Pulse energies up to 4 mJ, with diffraction-limited beam quality, are generated in
a 30-μm Yb-doped large-mode-area fiber, furthermore pulse energies up to 8 mJ are achieved from a multimode fiber amplifier.
Received: 8 May 2002 / Revised version: 10 July 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +49-3641/65-7680, E-mail: Jens.Limpert@uni-jena.de 相似文献
18.
A reliable and efficient method based on a geometrical optical approach is presented to model the propagation of ultrashort
pulses in optical systems. It is shown that the commonly used method to determine the group delay of the spectral components
of a pulse from their geometrical optical path lengths is only correct for aberration-free optical systems. In the case of
systems with angular dispersion and imaging errors, a correction to the path values obtained from ray-tracing calculations
must be applied, since for specific systems neglect of the correction causes significant errors. A technique for performing
this correction is presented. Two optical arrangements used for the generation and detection of tunable THz radiation by the
femtosecond tilted-pulse-front excitation technique are analyzed to demonstrate the indispensability of the correction.
Received: 29 July 2002 / Revised version: 22 October 2002 / Published online: 29 January 2003
RID="*"
ID="*"Corresponding author. Fax: +36-72/501-571, E-mail: kozma@fizika.ttk.pte.hu 相似文献
19.
R. Krupke F. Hennrich H.B. Weber D. Beckmann O. Hampe S. Malik M.M. Kappes H. v. Löhneysen 《Applied Physics A: Materials Science & Processing》2003,76(3):397-400
Single bundles of carbon nanotubes have been selectively deposited from suspensions onto sub-micron electrodes with alternating
electric fields. We show that it is possible to control the trapping of a single bundle by the use of Ag as electrode material
which, unlike Au, strongly interacts with the carboxyl functionalized carbon nanotubes. Excellent alignment of the bundles
between Au or Ag electrodes occurs at frequencies above 1 kHz, with superior contacts being formed with Ag electrodes.
Received: 22 May 2002 / Accepted: 21 June 2002 / Published online: 28 October 2002
RID="*"
ID="*"Corresponding author. Fax: +49-7247/82-6368, E-mail: ralph.krupke@int.fzk.de 相似文献
20.
W. Wang Z. Liu Y. Liu C. Xu C. Zheng G. Wang 《Applied Physics A: Materials Science & Processing》2003,76(3):417-420
Using a simple wet-chemical route, we synthesized CuO nanorods with diameters of ca. 5–15 nm and lengths of up to 400 nm.
The purity, crystallinity, morphology, structure features, and chemical composition of the as-prepared CuO nanorods were investigated
by powder X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron
spectroscopy, and Raman spectroscopy.
Received: 22 March 2002 / Accepted: 12 June 2002 / Published online: 28 October 2002
RID="*"
ID="*"Corresponding author. Fax: +86-25/359-5535, E-mail: wangqun@nju.edu.cn 相似文献