共查询到20条相似文献,搜索用时 46 毫秒
1.
CO-laser-based photoacoustic trace-gas detection: applications in postharvest physiology 总被引:3,自引:0,他引:3
J. Oomens H. Zuckermann S. Persijn D.H. Parker F.J.M. Harren 《Applied physics. B, Lasers and optics》1998,67(4):459-466
2 measurements using polarographic oxygen sensors.
Received: 13 March 1998/Revised version: 13 May 1998 相似文献
2.
Thermal grating and broadband degenerate four-wave mixing spectroscopy of OH in high-pressure flames
H. Latzel A. Dreizler T. Dreier J. Heinze M. Dillmann W. Stricker G.M. Lloyd P. Ewart 《Applied physics. B, Lasers and optics》1998,67(5):667-673
2 ∑–X2Π(0,0) band of OH has been studied in premixed methane/air flames using a cw Ar+ laser probe. Measurements of flame temperature and pressure were derived from fits of theoretical simulations to the observed
time variation of signals over a pressure range of 10 to 40 bar and for different stoichiometry that were in agreement with
independent measurements using N2 CARS and predictions of a one-dimensional flame calculation. Broadband DFWM spectra in the same band of OH were observed
up to a pressure of 9 bar, above which signals were obtained only from scattering from thermal gratings.
Received: 10 November 1997/Revised version: 28 May 1998 相似文献
3.
T.M. Di Palma A. Latini M. Satta A. Giardini-Guidoni 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(2):225-229
A photoionization study of the Me(NH3) clusters formed in the reaction of photoablated third group metal vapor with gaseous ammonia is reported. The photoionization
spectra exhibit some features due to vibrational excitation of ionic clusters and to transitions to neutral Rydberg states
leading to autoionization. DFT quantum chemical calculations are performed on the Me(NH3). The cluster geometries are fully optimized imposing the C3v symmetry. The calculated values of the IPs are in agreement with those experimentally determined.
Received: 16 February 1998 / Revised and Accepted: 7 May 1998 相似文献
4.
Characteristics of thermo-mechanical laser ablation process are investigated using an original numerical model. In contrast
with previous models, it is based on a microscopic physical model of the micro-explosion process, which combines thermodynamic
behavior of tissue water with elastic response of the solid tissue components. Diffusion of dissipated heat is treated in
one dimension, and the amount of thermal damage is assessed using the Arrhenius model of the protein denaturation kinetics.
Influence of the pulse fluence and duration on temperature profile development, ablation threshold, and depth of thermal damage
is analyzed for the case of Er:YAG laser irradiation of human skin. Influence of mechanical properties on the ablation threshold
of soft tissue is predicted theoretically for the first time. In addition, feasibility of deep tissue coagulation with a repetitively
pulsed Er:YAG laser is indicated from the model.
Received: 9 July 1998 / Revised version: 26 February 1999 / Published online: 26 May 1999 相似文献
5.
Ş. Yalçin D.R. Crosley G.P. Smith G.W. Faris 《Applied physics. B, Lasers and optics》1999,68(1):121-130
Received: 17 June 1998/Revised version: 17 September 1998 相似文献
6.
Received: 5 October 1998 / Accepted: 14 December 1998 / Published online: 24 February 1999 相似文献
7.
H. Fiedorowicz A. Bartnik R. Jarocki M. Szczurek T. Wilhein 《Applied physics. B, Lasers and optics》1998,67(3):391-393
Received: 20 April 1998/Revised version: 19 June 1998 相似文献
8.
J. Seres J. Klebniczki E. Seres J. Hebling 《Applied physics. B, Lasers and optics》1998,67(5):569-572
Received: 1 April 1998/Revised version: 20 April 1998 相似文献
9.
Polarization effects in ultrashort-pulse laser drilling 总被引:1,自引:0,他引:1
S. Nolte C. Momma G. Kamlage A. Ostendorf C. Fallnich F. von Alvensleben H. Welling 《Applied Physics A: Materials Science & Processing》1999,68(5):563-567
A strong influence of the polarization of the laser radiation on the geometry of laser-machined microdrillings has been observed
for ultrashort pulses. For drillings with a certain aspect ratio, reflections at the hole walls take place, leading to a non-uniform
intensity distribution deep inside the formed hole. Experimental and theoretical results on this subject are discussed. It
is shown that a rotation of the polarization during the drilling process (“polarization trepanning”) significantly improves
the quality of the produced holes.
Received: 21 August 1998 / Accepted: 25 November 1998 / Published online: 17 March 1999 相似文献
10.
Laser polishing of diamond plates 总被引:5,自引:0,他引:5
S.M. Pimenov V.V. Kononenko V.G. Ralchenko V.I. Konov S. Gloor W. Lüthy H.P. Weber A.V. Khomich 《Applied Physics A: Materials Science & Processing》1999,69(1):81-88
Results are reported on laser polishing of 150–400-μm-thick free-standing diamond films with either a copper vapor laser (510 nm
wavelength) or an ArF excimer laser (193 nm wavelength). Studies were focused on three particular goals. First, we aimed at
a choice of optimum conditions for laser polishing of thick diamond films. It was shown that the laser polishing conditions
and the resulting surface roughness were controlled by varying the angle of incidence of a scanning laser beam and by polishing
time. Second, the laser ablation technique was applied to remove a defective layer from the “substrate” side of the diamond
plates in order to reduce optical losses due to absorption in this layer. Third, the structure of the laser-graphitized diamond
surface was studied using UV, visible, and IR optical spectroscopy techniques in the course of the “step-by-step” oxidative
removal of the graphitic layer with increasing temperature of the oxidation in ambient air. Once the graphitic layer was removed,
the optical transmission in the UV-visible-IR spectral range of the diamond films polished under optimum conditions was measured
and compared with the optical transmission of the mechanically polished diamond films. It was shown that the optical quality
(in the long-wave infrared region) of the laser-polished diamond plates was sufficient to reach the transmittance value very
close to the theoretical limit.
Received: 20 October 1998 / Accepted: 8 March 1999 / Published online: 5 May 1999 相似文献
11.
J. Boneberg H.-J. Münzer M. Tresp M. Ochmann P. Leiderer 《Applied Physics A: Materials Science & Processing》1998,67(4):381-384
Received: 20 April 1998/Accepted: 2 June 1998 相似文献
12.
G.S. Duesberg J. Muster V. Krstic M. Burghard S. Roth 《Applied Physics A: Materials Science & Processing》1998,67(1):117-119
Received: 18 May 1998/Accepted: 22 May 1998 相似文献
13.
-30 Cm of isolated lines in the A1Σ+←X1Σ+ NaH transition band were measured.
Received: 18 November 1996/Revised version: 10 May 1997 相似文献
14.
Gas monitoring in the process industry using diode laser spectroscopy 总被引:10,自引:0,他引:10
2 , CO, NH3, HCl and HF are described together with measurements from several installations. The monitors show continuous measurements
with fast response and good sensitivity, all of which is difficult to obtain with conventional techniques such as wet chemical
analysis.
Received: 19 March 1998/Revised version: 2 June 1998 相似文献
15.
A portable modular gas sensor for measuring the 13C/12C isotopic ratio in CO2 with a precision of 0.8‰(±1σ) was developed for volcanic gas emission studies. This sensor employed a difference frequency generation (DFG)-based spectroscopic
source operating at 4.35 μm (∼2300 cm-1) in combination with a dual-chamber gas absorption cell. Direct absorption spectroscopy using this specially designed cell
permitted rapid comparisons of isotopic ratios of a gas sample and a reference standard for appropriately selected CO2 absorption lines. Special attention was given to minimizing undesirable precision degrading effects, in particular temperature
and pressure fluctuations.
Received: 16 April 2002 / Revised version: 28 May 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-713/5245237, E-mail: fkt@rice.edu 相似文献
16.
A. Stampanoni-Panariello B. Hemmerling W. Hubschmid 《Applied physics. B, Lasers and optics》1998,67(1):125-130
Received: 1 December 1997 / Revised version: 27 January 1998 相似文献
17.
The micromachining of hydroxyapatite (HAp) is highly important for orthopedics and dentistry, since human bone and teeth consist
mainly of HAp. We demonstrate ultrashort Ti:sapphire laser ablation of HAp, using pulse-widths of 50 fs, 500 fs, and 2 ps
at a wavelength of 820 nm and at 1 kpps. The crucial medical issue is to preserve the chemical properties of the machined
(ablated) surface. If the chemical properties of HAp change, the human bone or tooth cannot re-grow after laser processing.
Using X-ray photoelectron spectroscopy, we observe chemical properties of HAp ablated in air. The HAp is ablated at laser
fluences of 3.2 J/cm2 (6.4×1013 W/cm2 at 50 fs), 3.3 J/cm2 (6.6×1012 W/cm2 at 500 fs), and 9.6 J/cm2 (4.8×1012 W/cm2 at 2 ps), respectively. As a result it is found that the ablated surface is unchanged after laser ablation over the pulse-width
range used in this experiment.
Received: 7 October 2002 / Accepted: 20 January 2003 / Published online: 28 May 2003
RID="*"
ID="*"Corresponding author. Fax: +81-45/566-1533, E-mail: obara@obara.elec.keio.ac.jp 相似文献
18.
W.G. Bessler C. Schulz T. Lee D.-I. Shin M. Hofmann J.B. Jeffries J. Wolfrum R.K. Hanson 《Applied physics. B, Lasers and optics》2002,75(1):97-102
Planar laser-induced fluorescence (PLIF) images of NO concentration are reported in premixed laminar flames from 1–60 bar
exciting the A-X(0,0) band. The influence of O2 interference and gas composition, the variation with local temperature, and the effect of laser and signal attenuation by
UV light absorption are investigated. Despite choosing a NO excitation and detection scheme with minimum O2-LIF contribution, this interference produces errors of up to 25% in a slightly lean 60 bar flame. The overall dependence
of the inferred NO number density with temperature in the relevant (1200–2500 K) range is low (<±15%) because different effects
cancel. The attenuation of laser and signal light by combustion products CO2 and H2O is frequently neglected, yet such absorption yields errors of up to 40% in our experiment despite the small scale (8 mm
flame diameter). Understanding the dynamic range for each of these corrections provides guidance to minimize errors in single
shot imaging experiments at high pressure.
Received: 13 May 2002 / Published online: 8 August 2002 相似文献
19.
R. Wolleschensky T. Feurer R. Sauerbrey U. Simon 《Applied physics. B, Lasers and optics》1998,67(1):87-94
Received: 26 August 1997/Revised version: 2 February 1998 相似文献
20.
R. Brendel H. Artmann S. Oelting W. Frey J.H. Werner H.J. Queisser 《Applied Physics A: Materials Science & Processing》1998,67(2):151-154
2 for this waffle-shaped film when it is attached to glass substrates.
Received: 15 May 1998/Accepted: 28 May 1998 相似文献