共查询到20条相似文献,搜索用时 943 毫秒
1.
V. Sick 《Applied physics. B, Lasers and optics》2002,74(4-5):461-463
The potential use of planar laser-induced fluorescence (PLIF) of sulfur dioxide (SO2) for visualization of exhaust-gas distributions is outlined and demonstrated. Strong absorption features in the UV spectral
range allow excitation of SO2 with the fourth harmonic of a Nd:YAG laser at 266 nm. Fluorescence emissions are mostly red-shifted and can be easily detected
in single-shot imaging arrangements with a good signal-to-noise ratio. This study uses a premixed methane/air flame that is
doped with SO2 to demonstrate the technique. The signal strength has a pronounced temperature dependence for excitation at 266 nm.
Received: 14 January 2002 / Revised version: 30 January 2002 / Published online: 14 March 2002 相似文献
2.
R.L.D. Whitby W.K. Hsu C.B. Boothroyd K.S. Brigatti H.W. Kroto D.R.M. Walton 《Applied Physics A: Materials Science & Processing》2003,76(4):527-532
Time-dependent powder X-ray-diffraction analyses reveal that the conversion of WO3 into WS2 on carbon nanotube surfaces in the presence of H2S is a one-step process. The WS2 layers grow simultaneously along the tube in the radial and axial directions.
Received: 17 June 2002 / Accepted: 19 June 2002 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. Fax: +44-1273/677-196, E-mail: d.walton@sussex.ac.uk 相似文献
3.
Continuous-wave tunable Cr2+:ZnS laser 总被引:1,自引:0,他引:1
I.T. Sorokina E. Sorokin S. Mirov V. Fedorov V. Badikov V. Panyutin A. Di Lieto M. Tonelli 《Applied physics. B, Lasers and optics》2002,74(6):607-611
We report the first continuous-wave tunable over ∼280 nm around 2.3 μm room-temperature operation of a chemical vapor transport-grown
and diffusion-doped Cr2+:ZnS laser, pumped by a Co:MgF2 laser at 1.67 μm and generating over 100 mW of output power at 16% slope efficiency. The self-consistent results of the laser
and spectroscopic analysis demonstrate a large potential of this crystal as an active medium for diode-pumped tunable mid-infrared
sources.
Received: 7 January 2002 / Revised: 14 March 2002 / Published online: 2 May 2002 相似文献
4.
J.K. Jian X.L. Chen T. Xu Y.P. Xu L. Dai M. He 《Applied Physics A: Materials Science & Processing》2002,75(6):695-697
SnO2 nanowires were synthesized using a direct gas reaction route and were characterized by X-ray powder diffraction (XRD), scanning
electron microscopy (SEM), selected-area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM)
and Raman-scattering spectroscopy. XRD, SEM, SAED and HRTEM indicated that the products were tetragonal SnO2 nanowires with diameters of 10–50 nm. The nanowires were single crystal and solid inside. Dendritic nanowires were observed
for the first time. Three vibrational modes were observed in the Raman spectra of the samples.
Received: 7 January 2002 / Accepted: 11 April 2002 / Published online: 19 July 2002 相似文献
5.
LiMnO2 nanowire arrays were prepared using a porous anodic aluminum oxide (AAO) template from a sol–gel solution containing Li(OAc)
and Mn(OAc)2. Electron-microscope results showed that a uniform length and diameter of LiMnO2 nanowires were obtained, and the length and diameter of the LiMnO2 nanowires are dependent on the pore diameter and the thickness of the applied AAO template. X-ray diffraction and electron
diffraction pattern investigations demonstrate that LiMnO2 nanowires are a layered structure of LiMnO2 crystal. X-ray photoelectron spectroscopy analysis indicates that a material closely resembling stoichiometric layered LiMnO2 has been obtained.
Received: 2 September 2001 / Accepted: 6 January 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +86-931/891-2582, E-mail: lihl@lzu.edu.cn 相似文献
6.
R. Steiner H.-G. Boyen M. Krieger A. Plettl P. Widmayer P. Ziemann F. Banhart R. Kilper P. Oelhafen 《Applied Physics A: Materials Science & Processing》2003,76(1):5-13
[Fe/B]n ≥2 multilayers were prepared by thermal evaporation, ion-beam sputtering and laser ablation. By applying in situ electron spectroscopies
(UPS, XPS) and monitoring the electrical resistance during layer growth, evidence could be provided for the occurrence of
interface reactions within the range of studied deposition temperatures (77 K ≤T ≤300 K). These reactions result in amorphous
FexB100-x phases, which are spatially restricted to a width of less than 3 nm at the original interface. The amorphicity of the reacted
interlayers was unequivocally proven by additional high-resolution electron microscopy (HRTEM) and their characteristically
changed magnetic properties. Due to the well-defined width of the interface reaction, homogeneous amorphous FexB100-x films can be obtained by reducing the individual Fe and B layer thicknesses to below the above reaction depth, while for
larger thicknesses layer sequences of the crystalline/amorphous/crystalline type will result.
Received: 30 January 2002 / Accepted: 31 January 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +49-731/502-2963, E-mail: hans-gerd.boyen@physik.uni-ulm.de 相似文献
7.
Y. Chen D.A.A. Ohlberg G. Medeiros-Ribeiro Y.A. Chang R.S. Williams 《Applied Physics A: Materials Science & Processing》2002,75(3):353-361
Sub-monolayer amounts of Er deposited onto Si (001)react with the substrate to form epitaxial nanowires of crystalline ErSi2. The growth of uniaxial structures occurs because the different crystal structures of ErSi2 and Si have a good lattice match along one Si<110> crystallographic axis but a significant mismatch along the perpendicular
Si<110> axis. The nucleation, growth, and subsequent evolution of ErSi2 nanowires were investigated as functions of erbium coverage on the Si (001) surface, annealing time, and annealing temperature.
Low annealing temperatures (620 °C) and times (5 min) produced ErSi2 nanowires with widths of a few nanometers, heights less than one nanometer, and lengths of several hundred nanometers. For
longer annealing times at low temperature, the surface roughened without significant ripening of the wires. Annealing at intermediate
temperatures (∼700 °C) caused stacking faults to form along the long axis of the nanowires and their lengths to ripen. At
high temperature (800 °C), the wires broke apart into short segments with stacking faults.
Received: 30 January 2002 / Accepted: 31 January 2002 / Published online: 3 May 2002 相似文献
8.
We propose a novel technique of sub-Doppler spectroscopy using a thin vapor cell. Optical pumping in a thin cell transfers
atoms with small velocity components to a specific quantum state. The resultant velocity distribution appears as a sub-Doppler
structure in the absorption spectrum of a probe light. A single laser beam from a laser diode is split into two paths: one
beam optically pumps Cs atoms on the D2 line, and the other probes the absorption on the same line from a perpendicular direction. Observed hyperfine-resolved spectra
and their parameter dependence are analyzed on the basis of rate equations.
Received: 16 January 2002 / Revised version: 11 February 2002 / Published online: 24 April 2002 相似文献
9.
X. Liu Q. Lu P. Liu M. Zhao Z. Wang M. Ying F. Li L. Qin 《Applied Physics A: Materials Science & Processing》2003,76(2):273-275
Range distributions for bismuth ions implanted in AgGaSe2 in the energy range 80–300 keV were investigated by using 2.1-MeV He2+ Rutherford backscattering spectrometry (RBS). A convolution calculation method was used to extract the true distributions
of bismuth from the measured RBS spectra. The range distribution parameters, Rp and ΔRp, were obtained and compared with those obtained from Monte Carlo simulation. The experimental Rp values agree with the Monte Carlo simulation values very well, but the experimental ΔRp values are systematically larger than those from the theoretical simulation.
Received: 28 January 2002 / Accepted: 11 April 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +86-531/856-5167, E-mail: xdliu@sdu.edu.cn 相似文献
10.
W.-C. Su 《The European Physical Journal C - Particles and Fields》2003,28(1):147-150
The method of Abelian decomposition proposed by Faddeev and Niemi is used to derive the low-energy effective lagrangian of
G2 gauge theory. The G2 algebra is studied. The commutation relations among the generators of the G2 algebra are established, based on the framework of its regular maximal subalgebra, an SU(3) algebra.
Received: 19 December 2002 / Revised version: 10 January 2003 / Published online: 14 March 2003
RID="a"
ID="a" e-mail: suw@phy.ccu.edu.tw 相似文献
11.
D.-H. Lee Y. Yoon B. Kim J.Y. Lee Y.S. Yoo J.W. Hahn 《Applied physics. B, Lasers and optics》2002,74(4-5):435-440
A simple and reliable method is presented for optimizing the mode matching of a laser beam to the high-finesse cavity used
in pulsed cavity ringdown spectroscopy (CRDS). The method is based on minimizing the excitation of higher-order transverse
cavity modes through monitoring the non-degenerate transverse mode beating which becomes visible with induced cavity asymmetry
caused by slight misalignment. No additional instrument is required other than a pinhole aperture, thus this method can be
applied for CRDS experiments in the whole wavelength range. Measurements of the CRDS absorption spectrum of acetylene (C2H2) near 571 nm demonstrate that the mode-matching optimization improves the sensitivity of pulsed CRDS.
Received: 22 October 2001 / Revised version: 16 January 2002 / Published online: 14 March 2002 相似文献
12.
A.V. Kisselev V.A. Petrov R.A. Ryutin 《The European Physical Journal C - Particles and Fields》2003,26(4):597-600
Quark mass effects are analyzed at high Q2 in the current fragmentation region of DIS. It is found that the linear combination F
2
-2.75F
c
2 scales at large Q2 and small x. We obtained a lower bound for the ratio F
c
2/F
2
which lies very close to the data from HERA.
Received: 14 January 2002 / Revised version: 9 October 2002 Published online: 9 December 2002
RID="a"
ID="a" e-mail: ryutin@th1.ihep.su 相似文献
13.
G.F. Cerofolini 《Applied Physics A: Materials Science & Processing》2003,76(1):49-52
The thermodynamic and kinetic stabilities of the Si–H bonds at the Si–SiO2 interface are studied on the basis of high-level quantum-mechanical calculations in the framework of density-functional theory.
In the absence of an applied electric field, the silanic bond is shown to be stable with respect to both hole capture from
the top of the silicon valence band and electron loss to the bottom of the silicon conduction band, but unstable with respect
to hole capture from the top of the SiO2 conduction band. The positively charged hydrogen does not shift spontaneously to protonate a neighbouring siloxanic bridge
unless it contains one adsorbed water molecule at least. The protonated siloxanic site thus formed may restore the original
silanic site (via simultaneous electron capture from the conduction band and hydron shift to silicon) but also evolve spontaneously
to a hydrogen atom via simple electron capture.
Received: 2 November 2001 / Accepted: 6 January 2002 / Published online: 20 March 2002 / Published online: 20 March 2002
RID="*"
ID="*"Also at: STMicroelectronics, 20041 Agrate MI, Italy (E-mail: gianfranco.cerofolini@st.com) 相似文献
14.
E. Goering M. Justen J. Geissler U. Rüdiger M. Rabe G. Güntherodt G. Schütz 《Applied Physics A: Materials Science & Processing》2002,74(6):747-753
Highly a-axis-textured CrO2 films have been deposited on Al2O3 (0001) substrates by chemical vapor deposition. CrO2 has been found to have highly a-axis (010)-oriented columnar growth on a Cr2O3 (0001) initial layer. The six-fold surface symmetry of the Cr2O3 initial layer leads to three equivalent in-plane orientations of the a-axis-oriented CrO2 unit cell. We report Cr L2,3 X-ray magnetic circular dichroism data along the surface normal and at 60° off-normal sample orientation. For a 60° sample
alignment, a strong increase of the projected orbital moment could be observed for unoccupied majority t2g states using moment analysis. Therefore, the c axis is identified as the intrinsic magnetic easy axis of CrO2. In addition, a small spin moment and a very strong magnetic dipole term Tz have been found.
Received: 8 January 2002 / Accepted: 8 January 2002 相似文献
15.
Zirconium oxide layers have been successfully deposited by photo-CVD at low temperatures. ZrO2 growth was observed at temperatures as low as 100 °C. When deposited at 250 °C and above, these films exhibited a polycrystalline
structure with a mixture of different crystal phases. Deposition at 300 °C was found to form moisture-free ZrO2 films with a high refractive index of 2.1, a very low effective density of trapped electrons of ∼8.8×108 cm-2 and an interface trap density of 6.6×109 cm-2 eV-1 being readily obtained.
Received: 17 December 2001 / Accepted: 6 January 2002 / Published online: 3 June 2002 相似文献
16.
V.G. Shcherbitsky S. Girard M. Fromager R. Moncorgé N.V. Kuleshov V.I. Levchenko V.N. Yakimovich B. Ferrand 《Applied physics. B, Lasers and optics》2002,74(4-5):367-374
A rigorous approach taking into account both the temporal and spatial distributions of the pulsed probe beam used for transmission
measurements of solid-state saturable absorbers is applied to characterise these absorbers accurately. The use of this method
can significantly influence the resulting value for the ground-state absorption cross section. It also permits us to avoid
the introduction of an artificial excited-state absorption in systems where, according to energy-level diagrams, no such loss
should occur. This is illustrated in the case of passive Q-switchers for 1.5-μm lasers such as Co2+-doped LaMgAl11O19 and MgAl2O4 and Co2+- or Cr2+-doped ZnSe and ZnS.
Received: 21 November 2001 /
Revised version: 22 January 2002 / Published online: 14 March 2002 相似文献
17.
Comparison between c-cut and a-cut Nd:YVO4 microchip lasers passively Q-switched with a Cr4+:YAG saturable absorber is experimentally made. The lower emission cross section of the c-cut Nd:YVO4 crystal can enhance the passive Q-switching effect to produce a peak power 10 times higher than that obtained with the a-cut
crystal. The experimental result further reveals that a c-cut Nd:YVO4 crystal is a very convenient material for short-pulse (sub-nanosecond) and high-peak-power (>10 kW) lasers.
Received:10December2001/Revisedversion:22January2002 / Published online: 14 March 2002 相似文献
18.
N+BF<Subscript>2</Subscript> and N+C+BF<Subscript>2</Subscript> high-dose co-implantation in silicon
L. Barbadillo M. Cervera M.J. Hernández P. Rodríguez J. Piqueras S.I. Molina A. Ponce F.M. Morales 《Applied Physics A: Materials Science & Processing》2003,76(5):791-800
Nitrogen and boron BF2, and nitrogen, carbon, and boron BF2 high-dose (6×1016–3×1017 cm-2) co-implantation were performed at energies of about 21–77 keV. Subsequent high-temperature annealing processes (600, 850,
and 1200 °C) lead to the formation of three and two surface layers respectively. The outer layer mainly consists of polycrystalline
silicon and some amorphous material and Si3N4 inclusions. The inner layer is highly defective crystalline silicon, with some inclusions of Si3N4 too. In the N+B-implanted sample the intermediate layer is amorphous. Co-implantation of boron with nitrogen and with nitrogen
and carbon prevents the excessive diffusivity of B and leads to a lattice-parameter reduction of 0.7–1.0%.
Received: 10 January 2002 / Accepted: 30 May 2002 / Published online: 4 November 2002
RID="*"
ID="*"Corresponding author. Fax: +34-91/3974895; E-mail: Lucia.Barbadillo@uam.es 相似文献
19.
Y. Takagaki E. Wiebicke M. Ramsteiner L. Däweritz K.H. Ploog 《Applied Physics A: Materials Science & Processing》2003,76(5):837-840
Micrometer-size crystals are observed to grow spontaneously on chemically etched MnAs surfaces. The wet chemical etching leaves
a nearly exclusive pile of amorphous arsenic on the surface when the MnAs layer is etched incompletely. Using Raman spectroscopy,
we identify that these micro-crystals are the arsenolite crystal of arsenic oxides. The manganese in the MnAs layer is oxidized
by the hydrogen peroxide in the etch solution to MnO2, which then works as the catalyst for the rapid oxidation and crystallization of the amorphous arsenic.
Received: 14 November 2002 / Accepted: 18 November 2002 / Published online: 29 January 2003
RID="*"
ID="*"Corresponding author. Fax: +49-30/20377-515, E-mail: takagaki@pdi-berlin.de 相似文献
20.
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