共查询到20条相似文献,搜索用时 15 毫秒
1.
F. Kokai Y. Kakudate H. Togashi Y. Koga S. Fujiwara 《Applied Physics A: Materials Science & Processing》1995,60(1):31-34
Laser-ionization time-of-flight mass spectrometry has been used to probe laser-ablation products from a nitrogen-rich polymer at a wavelength of 308 nm. The ablation products at a laser fluence of 150 mJ/cm2 showed, similar to 532 nm ablation studied previously [18], two strong peaks due to neutral species that were assigned to C+ and CN+, as well as several weak peaks that were assigned to CH+, HCN+, HCNH+, HnN–CN+ (n=1–3), and H2N–C=N–CN+ or H2N–C=N–CN+. The ablation products at 870 mJ/cm2 revealed, in addition to a broad signal due to ionic products generated directly by the ablation laser, several peaks due to neutral products that were assigned to C+, C
2
+
, C
3
+
, CN+, HCN+, HCNH+, and NCCN+. The most probable flight velocities for major neutral products are 5.7×104 cm/s at 150 mJ/cm2 and 2.3–2.7×104 cm/s at 870 mJ/cm2. The results at a laser fluence of 150 mJ/cm2 support the finding that the translational energy of the tragments has importance for the collision-induced product generation in the laser plume, as suggested earlier [18]. Furthermore, the product generation at 870 mJ/cm2 is interpreted by the ejection of small neutral and ionic fragments, and subsequent reactions among the fragments. 相似文献
2.
V. Drinek H. Niino J. Pola A. Yabe 《Applied Physics A: Materials Science & Processing》2001,73(4):527-530
An organosilicon compound, hexamethylcyclotrisilazane (HMCTS), was photolyzed in a solid film at 84 K with an ArF excimer
laser. A polymeric film was prepared as a result of polymerization and/or crosslinking using a reactive species such as 1-(methylsilyl)methanimine,
generated by photolysis. At room temperature in air, the film changed into a polymer having siloxane units. However, fragments
generated by laser irradiation of HMCTS in the frozen film made a similar polymer film having a siloxane structure on a PVA
film in air. The polymeric film with siloxane units prepared by the cryogenic laser ablation method displayed hydrophobic
properties.
Received: 23 May 2001 / Accepted: 30 May 2001 / Published online: 30 August 2001 相似文献
3.
L. Torrisi S. Gammino L. And V. Nassisi D. Doria A. Pedone 《Applied Surface Science》2003,210(3-4):262-273
To study the solid Cu ablation in vacuum, two different laser sources operating at 1064 and 308 nm wavelength are employed at similar values of laser fluences. The infrared laser is a Q-switched Nd:Yag having 9 ns pulse width (INFN-LNS, Catania), while the ultraviolet one is a XeCl excimer having 20 ns pulse width (INFN-LEA, Lecce). Both experiments produced a narrow angular distribution of the ejected material along the normal to the target surface. The ablation showed a threshold laser power density, of about 7 and 3 J/cm2 at 1064 and 308 nm, respectively, below which the ablation effect was negligible. The laser interaction produces a plasma at the target surface, which expands very fast in the vacuum chamber. Time-of-flight (TOF) measurements of the ion emission indicated an average ion velocity of the order of 4.7×104 and 2.3×104 m/s for the infrared and ultraviolet radiation, respectively. We also estimated approximately the corresponding temperature of the plasma from which ions originated, i.e. about 106 and 105 K for IR and UV wavelength, respectively. A discussion of the analysis of the ablation mechanism is presented. At the used laser power densities the produced Cu ions showed ionisation states between 1+ and 5+ in both cases. 相似文献
4.
5.
4 m/s, shows the development of a shock wave in its front, resulting from the interaction between the species released from
the target and the background gas. The water vapor slows down this component up to values of about 3×103 m/s following a behavior that can be well described by the dynamics of a spherical shock wave. The low intensity of emission
of the second component has not allowed us to analyze its dynamics. The third and slowest component expands at a constant
velocity of 5×102 m/s and is constituted by hot particulates leaving the target. Spectra recorded in the shock front have shown the presence
of emission lines arising from Ca I, Ca II, P I and some impurities, and two strong emission bands that can be assigned to
some sort of calcium oxide.
Received: 7 November 1997/Accepted: 17 February 1998 相似文献
6.
Alex Spiro Mary Lowe Guerman Pasmanik 《Applied Physics A: Materials Science & Processing》2012,107(4):801-808
Experimental results on picosecond laser processing of aluminum, nickel, stainless steel, molybdenum, and tungsten are described. Hole drilling is employed for comparative analysis of processing rates in an air environment. Drilling rates are measured over a wide range of laser fluences (0.05–20?J/cm2). Experiments with picosecond pulses at 355?nm are carried out for all five metals and in addition at 532?nm, and 1064?nm for nickel. A comparison of drilling rate with 6-ps and 6-ns pulses at 355?nm is performed. The dependence of drilling rate on laser fluence measured with picosecond pulses demonstrates two logarithmic regimes for all five metals. To determine the transition from one regime to another, a critical fluence is measured and correlated with the thermal properties of the metals. The logarithmic regime at high-fluence range with UV picosecond pulses is reported for the first time. The energy efficiency of material removal for the different regimes is evaluated. The results demonstrate that UV picosecond pulses can provide comparable quality and higher processing rate compared with literature data on ablation with near-IR femtosecond lasers. A significant contribution of two-photon absorption to the ablation process is suggested to explain high processing rate with powerful UV picosecond pulses. 相似文献
7.
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
8.
Z. Q. Huang M. H. Hong T. B. M. Do Q. Y. Lin 《Applied Physics A: Materials Science & Processing》2008,90(1):159-163
TiB2-based cermets are prepared by combustion synthesis followed by a pressing stage in a granulate medium. Products obtained
by combustion synthesis are characterized by a large remaining porosity (typically 50%). To produce dense cermets, a subsequent
densification step is performed after the combustion process and when the reacted material is still hot. To design the process,
numerical simulations are carried out and compared to experimental results. In addition, physical and electrical properties
of the products related to electrical contact applications are evaluated.
PACS 81.20.Ka; 81.05.Mh; 72.80.Tm 相似文献
9.
2 to 2.5 mJ/cm2 when a 0.5 ps pulse is used instead of a 15 ns laser pulse. Measurements on liquid indium show a different behavior. With 15 ns
laser pulses the threshold fluence is lowered by a factor of ∼3 from 100 mJ/cm2 for solid indium to 30 mJ/cm2 for liquid indium. In contrast, measurements with 0.5 ps laser pulses do not show any change in the ablation threshold and
are independent of the phase of the metal at 2.5 mJ/cm2. This behavior could be explained by thermal diffusion and heat conduction during the laser pulse and demonstrates in an
independent way the energy lost into the material when long laser pulses are applied. Time-of-flight measurements to investigate
the underlying ablation mechanism show thermal behavior of the ablated indium atoms for both ps and ns ablation and can be
fitted to Maxwell-Boltzmann distributions.
Received: 2 December 1996/Accepted: 11 December 1996 相似文献
10.
The interaction phenomena of nanosecond time period Q-switched diode-pumped Nd:YAG laser pulses using 1064, 532 and 355 nm with 0.25 mm thick pure-copper foil was investigated at an incident laser intensity range of 0.5–57.9 GW/cm2. For each sample, etch rate and surface structure were determined. Analysis of the results of the tests included scanning electron microscopy (SEM). A maximum etch rate of 13.3 μm per pulse was obtained for the etch rate tests carried out at 532 nm. The maximum etch rate obtainable for 1064 nm was 2.21 μm per pulse, and for 355 nm, 6.68 μm per pulse. The dramatic decrease in etch rate observed when processing at 1064 nm is thought to occur due the highly reflective nature of copper as the interaction wavelength is increased, plus the nature of the plasma formed above the material during the high-intensity laser–material interaction. This plasma then imparts energy to the surface of the processed area leading to surface melting of the area surrounding the hole as can be seen by the SEM photographs. 相似文献
11.
Holmelund E. Thestrup B. Schou J. Larsen N.B. Nielsen M.M. Johnson E. Tougaard S. 《Applied Physics A: Materials Science & Processing》2002,74(2):147-152
Indium tin oxide (ITO) films have been deposited by pulsed laser deposition (PLD) at 355 nm. Even though the absorption of
laser light at the wavelength 355 nm is much smaller than that of the standard excimer lasers for PLD at 248 nm and 193 nm,
high-quality films can be produced. At high fluence and at high substrate temperatures, the specific resistivity of the films,
2–3×10-4 Ω cm, is comparable to values obtained with excimer lasers, whereas the resistivities obtained at room temperature are somewhat
higher than those of films produced by excimer lasers. The transmission coefficient of visible light, about 0.9, is also comparable
to values for films deposited by excimer lasers. The crystalline structure of films produced at 355 nm is similar to that
of samples produced by these lasers.
Received: 16 January 2001 / Accepted: 24 July 2001 / Published online: 17 October 2001 相似文献
12.
The multiply charged ions of C q + (q ≤ 4), O q + (q ≤ 6) were produced when a furan cluster beam interacted with nanosecond 1064 and 532 nm lasers at intensities of 1010–1012 W/cm2. It is shown that O6+ and C4+ ions were the dominant multiply charged species at 1064 nm, while C2+, C3+, O2+, O3+ ions were the main multiply charged species at 532 nm. By varying the electric field in the extraction region of the time of flight mass spectrometer (TOFMS), two types of ions were extracted, one of which had large kinetic energy and narrow space distribution, and the other had small kinetic energy and broad space distribution. The formation channels for He-like ions of C4+ and O6+ are discussed. 相似文献
13.
D.M. Karnakis 《Applied Surface Science》2006,252(22):7823-7825
We report on high intensity single-shot laser ablation of monocrystalline silicon with a nanosecond Nd:YAG at 355 nm. It is shown that for incident laser intensities exceeding ∼11.5 GW/cm2 on the silicon surface, unusually high etch depths can be achieved reaching values up to 60 μm. The results support previous observations of dramatic increase in etch rates in single-shot laser ablation at 266 nm. A laser-induced explosive boiling mechanism together with secondary plasma heating is believed to be associated with this effect. 相似文献
14.
M. Lassithiotaki A. Athanassiou D. Anglos S. Georgiou C. Fotakis 《Applied Physics A: Materials Science & Processing》1999,69(3):363-367
0 ∝t1/2. The best results are expected for a circular top-hat beam shape.
Received: 15 January 1999 / Accepted: 18 January 1999 相似文献
15.
Interaction of an Nd:YAG laser, operating at 1064 or 532 nm wavelength and pulse duration of 40 ps, with titanium implant was studied. Surface damage thresholds were estimated to 0.9 and 0.6 J/cm2 at wavelengths 1064 and 532 nm, respectively. The titanium implant surface modification was studied by the laser beam of energy density of 4.0 and 23.8 J/cm2 (at 1064 nm) and 13.6 J/cm2 (at 532 nm). The energy absorbed from the Nd:YAG laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following titanium/implant surface morphological changes were observed: (i) both laser wavelengths cause damage of the titanium in the central zone of the irradiated area, (ii) appearance of a hydrodynamic feature in the form of resolidified droplets of the material in the surrounding outer zone with the 1064 nm laser wavelength and (iii) appearance of wave-like microstructures with the 532 nm wavelength. Generally, both laser wavelengths and the corresponding laser energy densities can efficiently enhance the titanium/implant roughness. This implant roughness is expected to improve its bio-integration. The process of the laser interaction with titanium implant was accompanied by formation of plasma. 相似文献
16.
A.V. Karabutov V.D. Frolov E.N. Loubnin A.V. Simakin G.A. Shafeev 《Applied Physics A: Materials Science & Processing》2003,76(3):413-416
Low-threshold field electron emission (FEE) is reported for periodic arrays of micro-tips produced by laser ablation of Si
wafers. The best samples show emission at threshold fields as low as 4–5 V/μm for n-type Si substrates and of 1–2 V/μm for
p-doped Si substrates, as measured with a flat-screen technique. Auger electron spectroscopy and X-ray electron spectroscopy
reveal island-like deviation of the SiO2 stoichiometry on the tip surfaces, with lateral dimensions of less than 100 nm. Microscopic studies using a special field-emission
STM show that the emission originates from well-conducting regions of sub-micron size. The experimental data suggest FEE from
the tip arrays by a geometric field enhancement of both the individual micro-tip and the narrow conducting channels in the
tip body.
Received: 3 May 2002 / Accepted: 1 July 2002 / Published online: 28 October 2002
RID="*"
ID="*"Corresponding author. Fax: +7-095/135-82-34, E-mail: shafeev@kapella.gpi.ru 相似文献
17.
Cluster-assisted generation of multi-charged ions in nanosecond laser ionization of pulsed hydrogen sulfide beam at 1064 and 532nm 下载免费PDF全文
The multi-charged sulfur ions of Sq= (q\le 6) have been generated when hydrogen sulfide cluster beams are irradiated by a nanosecond laser of 1064 and 532,nm with an intensity of 1010\sim 1012W1\cdotcm-2. S6+ is the dominant multi-charged species at 1064nm, while S4+, S3+ and S2+ ions are the main multi-charged species at 532nm. A three-step model (i.e., multiphoton ionization triggering, inverse bremsstrahlung heating, electron collision ionizing) is proposed to explain the generation of these multi-charged ions at the laser intensity stated above. The high ionization level of the clusters and the increasing charge state of the ion products with increasing laser wavelength are supposed mainly due to the rate-limiting step, i.e., electron heating by absorption energy from the laser field via inverse bremsstrahlung, which is proportional to \lambda 2, \lambda being the laser wavelength. 相似文献
18.
利用Nd: YAG激光器研究基频(1064 nm)与倍频(532 nm)单独辐照和同时辐照下熔石英的损伤规律,对损伤几率进行了测试,获得损伤几率曲线与典型损伤形貌。研究结果表明:双波长同时辐照下的初始损伤阈值总是小于单波长辐照下的初始损伤阈值;基频光中加入定量倍频光后,熔石英对基频光的吸收效率提高;并且双波长同时辐照下,熔石英损伤密度增大;原因主要是熔石英表面缺陷对不同波长吸收机制的差异。 相似文献
19.
Z.-M. Ren P.-N. Wang Y.-C. Du Z.-F. Ying F.-M. Li 《Applied Physics A: Materials Science & Processing》1997,65(4-5):407-409
2 radicals when the 355 and 1064 nm outputs of a Nd:YAG laser were applied. While for the 532 nm ablation, a relatively higher
concentration of excited atomic carbon was obtained. Different Raman and FTIR spectral features were observed from the deposited
films with different ablation wavelengths. The 532 nm laser ablation is proposed for the synthesis of high quality carbon
nitride films.
Received: 16 October 1996 / Accepted: 11 April 1997 相似文献
20.
We analyze laser damage precursor evolution under multiple irradiations by changing test parameters such as shot number, wavelength, shot frequency, and test location (bulk or surface). The experimental data exhibit different behaviors under repetitive shots regarding the damage precursor densities and thresholds. The results provide new information for understanding the laser damage initiation process in silica. Furthermore, the data permit us to predict the lifetime of optical components under multiple irradiations. 相似文献