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state of RbCs
摘要： We perform a high-resolution Fourier-transform spectroscopic study of the (4) 1Σ state of the RbCs molecule by applying two-step (4) 1Σ ← A 1Σ+ ～ b 3Π ← X 1Σ+ optical excitation followed by observation of the (4) 1Σ → X 1Σ+ laser-induced fluorescence (LIF) spectra. In many LIF progressions the collision-induced satellite rotational lines are observed, thus increasing the amount of term values and allowing us to estimate the Λ-doubling effect in the (4) 1Σ state. The direct potential fit (DPF) of experimental term values of 777 rovibronic levels of both 85RbCs and 87RbCs isotopologues is performed by means of the robust weighted nonlinear least-squares method. The DPF analysis based on the adiabatic approximation and analytical expanded Morse oscillator potential reveals numerous regular shifts in the measured level positions. The spectroscopic studies of the (4) 1Σ state are supported by the electronic structure calculations including the potential energy curves of the singlet- and triplet-state manifold and spin-allowed transition dipole moments. The subsequent estimates of radiative lifetimes and corresponding vibronic branching ratios elucidate a dominant contribution of the (4) 1Σ → A ～ b channel into the total radiative decay of the (4) 1Σ state. The relative intensity distributions simulated for (4) 1Σ → X 1Σ+ LIF progressions agree well with their observed counterparts even for the profoundly shifted levels of the entirely perturbed (4) 1Σ state. To get insight into the origin of the intramolecular perturbations, the relevant spin-orbit- and L-uncoupling electronic matrix elements are evaluated.
关键词： electronic structure calculations,Fourier-transform spectroscopy,RbCs molecule,perturbed state,direct potential fit,laser-induced fluorescence,radiative properties
更新于2025-09-23 15:23:52
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[IEEE 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Greifswald (2018.9.23-2018.9.28)] 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Two Dimensional Distribution of Metallic (Cu) Vapor in a Forced Vacuum Arc Extinction by LIF
摘要： It is important to observe the metallic vapor dissipation after interrupting a vacuum arc, for getting a deeper understanding of dielectric recovery processes, especially for DC interruptions. The object of this paper is to obtain two dimensional density distribution of copper vapor in a forced vacuum arc extinction. The method of laser-induced fluorescence (LIF) using a pulse laser with a central wavelength at 324.8 nm was adopted here. Meanwhile, an ICCD was used to capture the 510.6 nm fluorescence signal with an exposure time of 50 ns. The fluorescence can be distinguished from 125 μs (the moment of arc extinction) to 375 μs with a time interval of 25 μs. As a result, we could obtain the relative density distribution of ground-state copper metal vapor after the arc extinction. The results show that on the condition of CuCr25 contacts the metal vapor was evenly distributed in the gap and rapidly spread over time. The density of the copper vapor between the contacts dropped to less than 10% of the initial stage 200 μs after arc extinction. On the contrary, on the condition of CuCr50, higher copper metal vapor density at the moment of arc extinction was observed. It seems that the higher Cr content in the Cu-Cr contacts will lead to producing more metal vapor around current zero.
关键词： laser-induced fluorescence,copper metal vapor,vacuum arc
更新于2025-09-23 15:22:29
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[IEEE 2018 13th International Congress Molded Interconnect Devices (MID) - Wu?rzburg (2018.9.25-2018.9.26)] 2018 13th International Congress Molded Interconnect Devices (MID) - Applications of Three Dimensional Laser Induced Metallization Technology with Polymer Coating
摘要： A fully developed three dimensional laser induced metallization (LIM) on molded interconnect devices (MIDs) is widely used on various products. The target substrate is sprayed with a special thin layer (50 μm) polymer coating first, and heated at 80°C to cure. Then using laser to define the pattern of conductors and induce the catalyst in the special polymer layer. After the electroless copper plating, the pattern is metallized. The whole process can be fully copy again on layer-by-layer to achieve the idea of multi-layer. For the high feasibility on any complex surface and material, such as glass, plastic, ceramic, etc., the LIM technology can be used for vary kind of products. In this paper, the LIM technology has applied on QR code stickers, 2G/3G/4G all-in-one compact antenna, mm-wave antenna, built-in antenna on mobile phone case, multi-layer NFC antenna, and humanoid robot finger. The QR code can be patterning on a thin film of 100 um and with a great flexibility. In addition, the return loss of 2G/3G/4G all-in-one compact antenna reaches the 3:1 VSWR standard, and the radiation efficiency is larger than 60% within the operation frequency. The built-in antenna on mobile phone case can reduce the waste of space and strongly secure the antenna from detachment. The LIM technology applied on the ceramic substrate can successfully fabricate a high directionality 38GHz mm-wave antenna and with above 10dBi of array gain, average efficiency up to 50%, and bandwidth up to 2 GHz. Furthermore, the multi-layer NFC antenna can successfully reduce the size and reach the maximum read distance of 3 cm. Using the same idea of multi-layer, the capacitive tactile sensor that can sense both normal and shear force is placed on humanoid robot finger to provide the tactile ability. The products described above will be briefly introduced in this paper and related testing results will be mentioned.
关键词： Antenna,Multilayer,3D-MID,Polymer Coating,Laser Induced Metallization
更新于2025-09-23 15:22:29
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Effect of temperature fields on optical properties of La <sub/>2</sub> Ti <sub/>2</sub> O <sub/>7</sub> thin films
摘要： In order to study the effect of temperature ?elds on the microstructure, optical properties and response to laser damage of La2Ti2O7 ?lms, a group of ?lms were prepared by electron beam evaporation using the same parameters on Si and fused silica substrates. Then, rapid thermal annealing at different temperatures was applied to simulate the application of a temperature ?eld. The structure, optical constants and response to laser damage of La2Ti2O7 ?lms were investigated by XPS, XRD, ellipsometry and laser damage testing. The results showed that Ti4+ is gradually converted to Ti3+ with increasing temperature resulting in a higher refractive index, larger extinction coef?cient and more serious absorption. When the temperature was higher than 800 °C, the loss of oxygen was more pronounced. The density of annealed ?lms ?rst increased and then decreased when the temperature rises from 600 to 1000 °C, and reached its maximum at 800 °C. And the crystallization, oxygen loss and densi?cation were found to be related to the laser damage threshold of La2Ti2O7 ?lm. The laser damage threshold of the ?lm decreased sharply when the temperature is above 900 °C.
关键词： temperature ?eld,optical properties,La2Ti2O7 ?lm,laser-induced damage
更新于2025-09-23 15:21:21
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Reduction of Radius of Curvature in Thin-Sheet-Metal Bending by Ultrashort-Pulsed Laser Peen Forming
摘要： Ultrashort-pulsed laser peen forming is a method of thin-sheet-metal forming using laser-induced shock waves. The authors have applied the process to microsheet parts bending, which is accomplished by repeating line scanning. However, when a severe curvature is requested, nonnegligible reduction of sheet thickness is induced by laser ablation. In order to restrict the thickness reduction, the authors attempted to improve the bending efficiency, which would allow a reduction in the number of necessary pulses. Scanning velocity and scanning pitch were changed, while the total irradiated pulse number was constant. The obtained results showed that a scanning velocity higher than the conventional one is favorable for improving the bending efficiency. In addition, smaller scanning pitches were adopted to reduce the radius of curvature. The influence of the scanning pitch on the bending efficiency was much weaker than that of scanning velocity. From the results of the evaluation of efficiency and scanned surface asperity, a scanning velocity of 20 mm·s-1 was judged to be the best. The best scanning condition achieved a 40% smaller radius of curvature than the conventional one.
关键词： bending,bending efficiency,laser-induced shock wave,ultrashort-pulsed laser,incremental forming,scanning velocity,forming property,laser peen forming
更新于2025-09-23 15:21:01
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Study on high-efficiency separation of laminated glass by skillfully combining laser-induced thermal-crack propagation and laser thermal melting
摘要： Laminated glass has a wide range of applications, but the cutting process is too cumbersome. In this paper, a novel laser composite separation method was proposed to separate the laminated glass by one time and simplify the cutting process from five steps to two steps for the first time by skillfully combining laser-induced thermal-crack propagation and laser thermal melting. This method generated three laser foci, and each laser focus is acting on one layer of laminated glass. Then, the composite mechanism combining laser-induced thermal-crack propagation for glass layers and laser thermal melting separation for PVB layer was realized to separate entire laminated glass. The experiments of separating laminated glass with thickness of 5 + 0.38 + 5 mm were carried out by laser composite separation successfully, and the separation side wall was very smooth (roughness of glass layer reached 10.24 nm) without any separation defects such as chipping, micro-cracks or subsurface damage. A mathematical model was also established to analyze the separation mechanism.
关键词： Laser melting,Numerical simulation,Laser-induced thermal-crack propagation,Laser separation,Laminated glass
更新于2025-09-23 15:21:01
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Evaluation of nitric oxide laser-induced fluorescence thermometry techniques in a hypersonic boundary layer
摘要： Nitric oxide planar laser-induced fluorescence was performed to measure the wall-normal distribution of static temperature through a hypersonic boundary layer. A 10-degree half-angle wedge model was oriented at a 5-degree angle of attack in the NASA Langley 31-in Mach 10 facility, resulting in a 5-degree flow turning angle and an edge Mach number of 7.6. Nitric oxide was seeded through a spanwise slot into the boundary layer upstream of the imaging region and was excited with a pulsed ultraviolet planar laser sheet. The laser was spectrally scanned across six fluorescence transitions in the (0, 0) band of the A2Σ+–X2Π system. Eighteen thermometry methods were assessed through comparison to predictions of the temperature field from computational fluid dynamics simulations. The effect of spectral resolution and laser linewidth on measurement uncertainty was also investigated. The most accurate technique was spectral peak thermometry, which achieved an accuracy of ± 31.6 K (12.6% error relative to CFD temperature). The spectral peak thermometry technique required a minimum spectral resolution between 0.074 and 0.102 cm?1 to extract meaningful temperature information from the spectra and a maximum laser linewidth of 0.49 cm?1.
关键词： Laser linewidth,Thermometry,Spectral resolution,Planar laser-induced fluorescence,Hypersonic boundary layer,Nitric oxide
更新于2025-09-23 15:21:01
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Laser-induced graphitized periodic surface structure formed on tetrahedral amorphous carbon films
摘要： Femtosecond laser-induced periodic surface structure (LIPSS), graphitization and swelling observed on ultra-hard, hydrogen-free tetrahedral amorphous carbon (ta-C) films are examined and compared with those on hydrogenated amorphous carbon (a-C:H) films, nitride films, and glassy carbon plates. The threshold fluence for LIPSS formation on ta-C is approximately twice as high as that for other specimens, and the LIPSS period Λ near the threshold is very fine at ca. 80 nm. Λ gradually increases with increasing fluence, and rapidly increases to ca. 600 nm at a high fluence. The ablation rate also increases rapidly at this fluence. In addition, ta-C and a-C:H are graphitized by irradiation and expand in volume. The surface layer of ta-C film changes to nanocrystalline graphite as the fluence increases and the crystallinity is improved; however, at higher fluence, the crystallinity deteriorates suddenly similar to that at low fluence. At high fluence, the rapid increase in Λ and the ablation rate, and the sudden deterioration in crystallinity are determined as common phenomena for these disordered carbons. LIPSS formation and swelling over a large area by scanned spot irradiation produces submicron height flat hills with conductivity and surface functionality on the insulating surface.
关键词： Graphitization,Swelling,Laser-induced periodic surface structure,Femtosecond-laser processing,Nanocrystalline graphite,Tetrahedral amorphous carbon
更新于2025-09-23 15:21:01
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Detection of Nutrition and Toxic Elements in Pakistani Pepper Powders Using Laser Induced Breakdown Spectroscopy
摘要： In the current paper, we applied laser induced breakdown spectroscopy (LIBS) to determine the elemental distribution of nutritional and trace heavy metals in pepper powders available in Pakistan using standard calibration curve laser induced breakdown spectroscopy (CC-LIBS) technique. The samples were found to contained elements like K, Ca, Mg, Na, Fe, Zn, Al, Pb, Cu, and Cr. Additionally, we also identified the atmospheric H-alpha line of hydrogen in the spectra which was used to estimate the electron number density. To achieve a highly sensitive LIBS system to determine nutritional and trace amounts of toxic metals in pepper powders and to achieve the best limit of detection, the LIBS system was optimized by studying the dependency of LIBS signal intensity on laser irradiance, variation in spacing between the focusing lens and target as well on the gate width. To justify the results of LIBS study, we also determined the concentration of alike (duplicate) peppers by digesting samples in appropriate solvents using a standard method like inductively coupled plasma-optical emission spectrometry (ICP-OES). The minimum detection limit was recognized for trace heavy metals from calibration curves. The results of LIBS displayed noteworthy conformity with those acquired from the ICP-OES analysis. Results of both the techniques clearly revealed that K was the most abundant element in all the peppers followed by Ca, Mg, Na, Fe, Al, Pb, Zn, Cu, and Cr. The relative accuracy of our LIBS system for different species as compared with ICP technique was in the range of 0.08–0.3 at 2.5 % error confidence. Conclusively, the present work demonstrated the suitability of LIBS technique due to its rapid, non destructive and eco-friendly approach for food security.
关键词： ICP-OES,detection of heavy metals,peppers analysis,laser induced breakdown spectroscopy,plasma parameters,Health impacts of toxic metals,laser applications
更新于2025-09-23 15:21:01
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Different material modifications in laser-induced damage of optical films in air and vacuum environments
摘要： A combination study of material modifications for the catastrophic laser-induced damage by 12 ns, 1064 nm laser pulse irradiation was investigated in air and vacuum environments. The samples were observed by optical microscope, scanning electron microscopy, laser micro-Raman spectroscopy, photoluminescence spectrum; moreover 2D numerical calculations were performed. According to our results, vacuum pumping induced higher laser field intensities, accompanying with more absorption of laser energy in the laser-induced damage process. All of these resulted in the material melting and subsequent re-solidification in the laser-damaged core in vacuum. While, in the air conditions, plasma expanding due to material heating and associated thermal expansion induced a large stress field, which caused the material deformation and formation of delamination and crack in the laser-damage region.
关键词： Vacuum,Photoluminescence spectrum,Laser-induced damage,Laser micro-Raman spectroscopy
更新于2025-09-23 15:21:01