共查询到20条相似文献,搜索用时 15 毫秒
1.
S. Mahmood S.A. Abbasi S. Jabeen M.A. Baig 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(5):689-695
We present laser-induced breakdown spectroscopic studies of variety of marbles extracted from Quetta region of Boluchistan, Pakistan using a Nd:YAG laser (532 nm) in conjunction with LIBS 2000 detection system. The emission spectra of Onyx (white spot) and Quetta Green Marble samples have been recorded as a function of laser irradiance. The elemental composition and their relative abundance in each sample are fond to be quite different. In Onyx (white spot), calcium dominates while in the Quetta Green marble magnesium is the dominant element. In addition the effect of the laser irradiance on the emission intensity, width and shift of the transition lines have been studied. 相似文献
2.
Laser-induced breakdown spectroscopy: A versatile tool for monitoring traces in materials 总被引:1,自引:0,他引:1
Laser-induced breakdown spectroscopy (LIBS) is an emerging technique for simultaneous multi-elemental analysis of solids,
liquids and gases with minute or no sample preparation and thus revolutionized the area of on-line analysis technologies.
The foundation for LIBS is a solid state, short-pulsed laser that is focused on a sample to generate a high-temperature plasma,
and the emitted radiation from the excited atomic and ionic fragments produced within the plasma is characteristic of the
elemental composition of the sample that can be detected and analyzed using a suitable optical spectrograph. In the present
paper, the applicability of LIBS for different solid samples having homogeneous (silver ornament, aluminum plate) or heterogeneous
composition (soil) using nanosecond laser pulses is discussed. Nanosecond pulse laser makes plasma at the sample surface even
at very low pulse energies and also allows for precise ablation of the substrate material with little damage to the surrounding
area. We have also studied the penetration of different heavy metals inside the soil surface.
相似文献
3.
Laser-induced breakdown spectroscopy (LIBS) in the last decades has become a promising analytical technique for a broad variety of archeological objects with great results obtained either alone or in combination with complementary techniques. It is mainly advantageous due to no sample preparation, minimally destructive, rapid analysis and depth profiling analysis spur LIBS technique to become a significant attractive technique for the characterization and conservation of archeological samples or artworks. The present paper describes in brief the basic principles and instrumentation of LIBS, and reviews several case studies on metallic alloys, ceramic, glass, painted artworks, historical buildings and biomaterials in the most recent 7 years (2011–2017) that demonstrate the applicability and prospects of LIBS in the field of archeological science. 相似文献
4.
5.
A detailed investigation of aluminum plasma induced by a 1064 nm Nd:YAG laser in air was performed. The emission of spectral lines arising from Al I transition at 396.07 nm, Al II transition at 358.46 nm, Al III transition at 360.72 nm and Al IV transition at 363.05 nm were well-resolved. The plasma parameters including electron temperature and electron density were determined through the Boltzmann plot method using the emission line intensities of the same ionized stages of aluminum atoms and the Stark-broadening profiles of Al II emission line, respectively. The temporal evolutions of the spectral lines belonging to atomic and ionic aluminum elements and the plasma parameters were investigated at three different laser pulse energies. Moreover, the validity of local thermodynamic equilibrium was elucidated in our experimental condition. 相似文献
6.
This work investigates the use of laser-induced gas breakdown for simultaneously igniting and measuring fuel-to-air ratio of CH4–air and H2–air combustible mixtures. The fuel-to-air ratio is determined using the measured spectral peak ratio Io,Hα/Io,OI. Sparks are produced using a single-mode, Q-switched Nd–YAG laser. The laser produces a beam of 6 mm in diameter at the wavelength of 1064 nm and pulse duration of 5.5 ns. The beam optics is designed to have mainly a beam splitter and a focusing lens. The beam splitter is coated to reflect the laser beam and transmit emission lines with wavelengths from 600 to 900 nm which are then collected by a fiberoptic cable and detected by an imaging spectrometer–detector assembly. The results showed a linear dependence of the spectral peak ratio on the equivalence ratio that can be generally expressed by φ=a(Io,Hα/Io,OI)+b, where a and b are the parameters that depend on the gas pressure. Using the least-square curve fitting technique to fit the experimental data, a calibration curve for calculating the equivalence ratio as a function of the ratio of (Io,Hα/Io,OI) was generated. 相似文献
7.
Y. Matsuoka 《Applied Physics A: Materials Science & Processing》2007,88(2):319-322
Using the fourth harmonic of a Q-switched Nd:YAG laser, the formation of a trepanned through hole of 1 mm in diameter in borosilicate
glass of 140 μm thickness was achieved. The number of circular scans required to form a trepanned through hole, decreased
rapidly with an increase in the number of the lines (circles) per circular scan. This result is interpreted as a decrease
of beam propagation losses in the groove with an increase in the groove width. The number of irradiation pulses required to
form a trepanned through hole increased rapidly with an increase in the number of lines (circles) per circular scan. The optimum
condition for forming a trepanned through hole arises from the relationship between the irradiation pulse energy density,
the number of irradiation pulses, and the number of lines (circles) per scan.
PACS 52.38.Mf; 42.70.Ce; 42.62.Cf 相似文献
8.
9.
Laser-induced breakdown spectrum has been recorded in the region of 380–455 nm using second harmonics of Nd:YAG laser, computer-controlled
TRIAX 320 M monochromator with a reciprocal linear dispersion 2.64 nm/mm fitted with ICCD detector. The spectrum consists
of 108 bands, which are classified into four new subsystems E0
u
+
(1Σ
u
+
) → A1g(3Πg), J0
g
±
\1g(3Σ
g
+
) → D1u(1Πu), F1u → A0
g
±
(3Πg) and F1u → A2g(3Πg) along with additional bands of the known system E0
u
+
(1Σ
u
+
) → A0
g
±
(3Πg). The molecular constants for these systems have also been determined. 相似文献
10.
Zhe Wang Ting-Bi Yuan Zong-Yu Hou Wei-Dong Zhou Ji-Dong Lu Hong-Bin Ding Xiao-Yan Zeng 《Frontiers of Physics》2014,9(4):419-438
Laser-induced breakdown spectroscopy (LIBS) has been regarded as a future superstar for chemical analysis for years due to its unique features such as little or no sample preparation, remote sensing, and fast and multi-element analysis. Chinese LIBS comnmnity is one of the most dynamically developing communities in the World. The aim of the work is to inspect what have been done in China for LIBS development and, based on the understanding of the overall status, to identify the challenges and opportunities for the future development. In this paper, the scientific contributions from Chinese LIBS comlnunity are reviewed for the following four aspects: fimdamentals, instrumentation, data processing and modeling, and applications; and the driving force of LIBS development in China is analyzed, the critical issues for successful LIBS application are discussed, and in our opinion, the potential direction to improve the technology and to realize large scale commercialization in China is proposed. 相似文献
11.
J. Zhang K. Sugioka K. Midorikawa 《Applied Physics A: Materials Science & Processing》1998,67(5):545-549
+ :YAG laser (266 nm) is reported. With the assistance of plasma resulting from laser irradiation on a metal target, the fused-quartz
substrate is easily etched by the 266-nm laser beam in spite of the fact that the substrate is transparent to this wavelength.
In contrast, no ablation takes place without the metal target, but damage is generated on the substrate surface. The ablated
region is observed by optical microscopy and scanning probe microscopy (SPM), which reveal a fine grating structure (line
spacing of 20 μm) without any severe damage. A series of experiments on the dependence of the ablation rate and the threshold
laser fluence on ablation parameters, such as laser fluence, the number of pulses, and the distance between the fused quartz
and the metal target is performed. On the basis of the results, three possible mechanisms of direct plasma interaction, plasma
heating, and metal film deposition are discussed.
Received: 27 February 1998/Accepted: 5 June 1998 相似文献
12.
In this study, the vibration phenomenon during pulsed laser forming of thin metal plates was investigated numerically and experimentally. The metal plates were made of 304 stainless steel and were heated by a CO2 Gaussian laser beam with a long pulse duration of 0.1 s, which incited vibration due to the elastic–plastic deformation of the specimen. This uncoupled thermal–mechanical problem was solved using a three-dimensional finite element method and was subsequently satisfactorily verified with experiments. Using the superposition method with multiple laser pulses, the non-linear vibration phenomenon during pulsed laser forming has also been observed experimentally for thin plates. 相似文献
13.
Weidong Gao Meiqiong Zhan Shuhai Fan Janda Shao Zheng-Xiu Fan 《Applied Surface Science》2005,250(1-4):195-202
The laser-induced damage (LID) behavior of narrow-band interference filters was investigated with a Nd:YAG laser at 1064 nm under single-pulse mode and free-running mode. The absorption measurement of such coatings was performed with surface thermal lensing (STL) technique. The damage morphologies under the two different laser modes were also studied in detail. It was found that all the filters exhibited a pass-band-center-dependent absorption and laser-induced damage threshold (LIDT) behavior, but the damage morphologies were diverse. The explanation was given with the analysis of the electric field distribution and the operational behavior of the irradiation laser. 相似文献
14.
Single shot nanosecond polarization resolved laser induced breakdown spectroscopy is introduced to spectrally analyse solid sample, e.g. copper. It is shown that continuum background emission of plasma generated by such laser pulse is much strongly polarized than discrete line radiation. By using the PRLIBS technique, continuum background emission is effectively suppressed. Furthermore, it is illustrated that polarization state of continuum emission in copper sample is mostly in vertical direction and, also, does not depend on laser beam polarization. 相似文献
15.
A new method for improving the efficiency of laser drilling has been developed. Two synchronized free-running laser pulses
from a tandem-head Nd:YAG laser are capable of drilling through 1/8-in-thick stainless-steel targets at a stand-off distance
of 1 m without gas-assist. The combination of a high-energy laser pulse for melting with a properly tailored high-intensity
laser pulse for liquid expulsion results in the efficient drilling of metal targets. We argue that the improvement in drilling
is due to the recoil pressure generated by rapid evaporation of the molten material by the second laser pulse.
Received: 29 August 2000 / Accepted: 18 December 2000 / Published online: 3 April 2001 相似文献
16.
17.
U. J. Greiner H. H. Klingenberg D. R. Walker C. J. Flood H. M. van Driel 《Applied physics. B, Lasers and optics》1994,58(5):393-395
We have examined the performance of a diode-laser side-pumped Nd:YAG laser using elliptical mirrors to focus the output of 6 × 10 W laser-diode arrays into the Nd: YAG rod. The multimode cw output power was 14 W with an optical to optical efficiency of 29%. With a resonator designed for TEM00 mode operation 12 W of output was achieved. 相似文献
18.
With the ever-increasing amount of generated waste governments around the world are looking for, and implementing, ways to minimize waste output and maximize waste recovery. The main difficulties are sorting waste items, identifying the different types of plastics, and the time taken to sort them manually. Bioplastics such as polylactic acid and Novatein thermoplastic protein can be incorporated into the recycling stream to minimize waste. Laser-induced breakdown spectroscopy spectra analyzed by k-nearest neighbor and soft independent modeling by class analogy were investigated as methods that can rapidly identify recyclables. Raw, peak normalized, and total intensity normalized spectra were used to identify which would improve classification. Laser-induced breakdown spectroscopy spectra were generated by single laser shots to different locations on nine samples, glass (brown, green, and clear), tin, aluminum, polylactic acid, Novatein, polyethylene terephthalate, and high-density polyethylene. To prove that the system has the potential to be used on a waste sorting stream an autofocus unit was developed to move the laser-induced breakdown spectroscopy beam into focus on the different sample geometries. Two classification methods were investigated, soft independent modeling by class analogy and the k-nearest neighbors algorithm. k-Nearest neighbors on raw spectra produced the best results. Discrimination between bioplastics and plastics were 100%. Glass samples could not be reliably distinguished from each other. Surface contamination produced three misclassifications from 450 spectra. Similar results were obtained when the spectral range was reduced from 182.26–908.07?nm to 313.20–495.12?nm. 相似文献
19.
Light from a Nd:YAG laser at 1064 nm is independently stabilized to two Fabry-Perot etalons situated on separate vibration-isolation platforms. A heterodyne beat measurement shows their relative frequency stability to be at the part-in-10(15) level at 5 s and the relative linewidth to be less than 1 Hz. 相似文献
20.
Bashir Ahmed Tahir Rashid Ahmed M. G. B. Ashiq Afaq Ahmed M. A. Saeed 《中国物理 B》2012,21(4):44201-044201
This study deals with Nd:YAG laser cutting nonmetallic materials, which is one of the most important and popular industrial applications of laser. The main theme is to evaluate the effects of Nd:YAG laser beam power besides work piece scanning speed. For approximate cutting depth, a theoretical study is conducted in terms of material property and cutting speed. Results show a nonlinear relation between the cutting depth and input energy. There is no significant effect of speed on cutting depth with the speed being larger than 30 mm/s. An extra energy is utilized in the deep cutting. It is inferred that as the laser power increases, cutting depth increases. The experimental outcomes are in good agreement with theoretical results. This analysis will provide a guideline for laser-based industry to select a suitable laser for cutting, scribing, trimming, engraving, and marking nonmetallic materials. 相似文献