- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Direct Determination of Ground-State Transition Widths and Natural Level Widths with the Method of Relative Self Absorption
摘要： The method of relative self absorption is based on the technique of nuclear resonance ?uorescence measurements. It allows for a model-independent determination of ground-state transition widths, natural level widths, and, consequently, of branching ratios to the ground state for individual excitations. Relative self-absorption experiments have been performed on the nuclei 6Li and 140Ce. In order to investigate the total level width for the 0+1 , T = 1 level at 3563 keV in 6Li, a high-precision self-absorption measurement has been performed. In the case of 140Ce, self absorption has been applied for the ?rst time to study decay widths of dipole-excited states in the energy regime of the pygmy dipole resonance.
关键词： 6Li,natural level widths,nuclear resonance fluorescence,ground-state transition widths,140Ce,branching ratios,relative self absorption,pygmy dipole resonance
更新于2025-09-23 15:21:21
-
Diagnosis of copper plasma by laser induced breakdown spectroscopy
摘要： In this paper influence of laser energy on the emission spectrum of laser copper-interaction and plasma parameter for plasma Copper by used a first harmonic generated wavelength of Nd:YAG exaction source. The metal plasma that had detection by HR4000 detection system (ocean optics) was use to different excited. plasma temperature via the Boltzmann plot diagram with measuring the electron density number by McWhirter CRITERION. Values of measuring (Ne), (Te) found between (61178776 K°) and (Ne) is (1.77*1015, 2.01*1015 cm-3) at 1064nm.
关键词： LIBS,Copper plasma,electron number density,self-absorption,plasma parameter
更新于2025-09-23 15:21:01
-
Design Principles of Narrow and Wide Bandgap-Based Betavoltaic Batteries
摘要： A Monte Carlo electron transport code PENELOPE was used to analyze beta particle energy deposition in semiconductors for titanium tritide and beryllium tritide. The source thickness was incorporated into the model in order to take into account the self-absorption of beta particles in the source material. Furthermore, an isotropic source was modeled with the full beta energy spectrum of tritium to make the beta particle transport method more realistic. The simulated results for a 0.4-μm-thick titanium tritide source with silicon carbide agreed well with the experimental results. The simulated results obtained for an optimized 2.5-μm-thick beryllium tritide source with silicon carbide was about two times higher than the power for a 0.4-μm-thick titanium tritide source with silicon carbide. An approximately two times higher short-circuit current density was obtained for beryllium tritide with silicon compared to silicon carbide. However, the power output density was about 10× higher for silicon carbide. The width of the depletion region for a p-type dopant concentration of 1×1019/cm3 and an n-type dopant concentration of 5×1014/cm3 is about 1.4 and 2.5 μm in silicon and silicon carbide, respectively. The estimated beta particle penetration depth is about 1.48± 0.015 and 1.03 ± 0.015 μm in silicon and silicon carbide, respectively. This suggests that the proper choice of dopant concentrations will achieve greater energy deposition in the depletion region, which in turn will increase the power output.
关键词： design principles of betavoltaic batteries,Beta particle energy deposition,self-absorption
更新于2025-09-23 15:21:01
-
Absolute density measurement of hydrogen atom in inductively coupled Ar/H2 plasmas using vacuum ultraviolet absorption spectroscopy
摘要： The absolute density measurement of atomic species such as hydrogen is crucial for plasma processing because of their strong chemical reactivity. In this work, to measure the hydrogen atom density in Ar/H2 inductively coupled plasmas (ICP), the self-absorption-applied vacuum ultraviolet absorption spectroscopy (VUVAS) is studied with a micro-hollow cathode H2/He discharge lamp (MHCL) emitting VUV light (Lyman alpha line; Lα 121.56 nm). The absolute density of hydrogen atoms in the ICP is investigated for various powers (50 W–850 W) in the low pressure region (30 mTorr–50 mTorr). The hydrogen density in remote plasma region is shown to vary from 2.1 × 1011 cm?3 to 1.25 × 1012 cm?3 with respect to plasma power.
关键词： VUV absorption spectroscopy,Low-pressure,Self-absorption,Hydrogen atom density,inductively coupled plasma
更新于2025-09-23 15:19:57
-
Investigation of the multi-elemental self-absorption mechanism and experimental optimization in laser-induced breakdown spectroscopy
摘要： The self-absorption effect reduces the accuracy of elements measurement in laser-induced breakdown spectroscopy (LIBS) experiments. In this paper, the mechanism of the self-absorption effect was studied. First, we established a plasma concentration distribution model and plasma dynamics model of the plasma expansion in three directions during LIBS based on physical laws. By coupling a plasma concentration distribution model with a self-absorption model, the LIBS self-absorption effect value model was obtained. Second, the models were applied in a numerical simulation to determine plasma spatial distribution characteristics during LIBS. The self-absorption effect values of spectral lines were calculated. Finally, experiments were conducted with an optical spectrometer to obtain the Na, K, and Al atomic emission spectra. On the theoretical plane, the Boltzmann plot method and the Stark broadening method were used to obtain the plasma characteristic parameters. The spectral line intensities of the Na, K and Al atom lines were obtained without and with microwave-assisted LIBS experiments for comparison. The experimental analysis showed that during the LIBS process, microwave assistance can enhance the emission spectroscopy intensity and inhibit or reduce the LIBS self-absorption effect. The experimental samples were in good agreement with those of theoretical simulation, indicating the effectiveness and practicability of the created LIBS self-absorption effect value model, which can improve the optimization of the LIBS process.
关键词： Self-absorption,LIBS,Numerical simulation,Spectral analysis,Material surface
更新于2025-09-23 15:19:57
-
Reliability of rare-earth-doped infrared luminescent nanothermometers
摘要： The use of infrared-emitting rare-earth-doped luminescent nanoparticles as nanothermometers has attracted great attention during the last few years. The scientific community has identified rare-earth-doped luminescent nanoparticles as one of the most sensitive and versatile systems for contactless local temperature sensing in a great variety of fields, but especially in nanomedicine. Researchers are nowadays focused on the design and development of multifunctional nanothermometers with new spectral operation ranges, outstanding brightness, and enhanced sensitivities. However, no attention has been paid to the assessment of the actual reliability of the measurements provided by rare-earth-doped luminescent nanothermometers. In fact, it is assumed that they are ideal temperature sensors. Nevertheless, this is far from being true. In this work we demonstrate that the emission spectra of rare-earth-doped nanothermometers can be affected by numerous environmental and experimental factors. These include the numerical aperture of the optical elements used for their optical excitation and luminescence collection, the local concentration of nanothermometers, optical length variations, self-absorption of the luminescence by the nanothermometers themselves, and solvent optical absorption. This work concludes that rare-earth-doped luminescent nanothermometers are not as reliable as thought and, consequently, special care has to be taken when extracting temperature estimations from the variation of their emission spectra.
关键词： reliability,solvent absorption,self-absorption,excitation power dependence,infrared luminescent nanothermometers,rare-earth-doped
更新于2025-09-19 17:15:36
-
Influence of laser wavelength on self-absorption effect in laser-induced breakdown spectroscopy
摘要： Self-absorption effect seriously affects the accuracy of the quantitative analysis in laser-induced breakdown spectroscopy (LIBS), confining the further development of the technology. In this study, three laser wavelengths at ultraviolet (355 nm), visible light (532 nm), and infrared (1064 nm) were selected to study the influence of laser wavelength on self-absorption effect in LIBS. The effect of the laser wavelength the on spectral stability was also investigated. The results showed that when the wavelength was 1064 nm compared with the wavelength of 355 nm and 532 nm, the full widths at half maximum (FWHMs) of aluminum (Al) I 396.2 nm were reduced by 39% and 23%, the FWHM of potassium (K) I 766.5 nm were reduced by 58% and 22%. In addition, the laser wavelength was also closely related to the stability of the spectral intensity. In comparison with the laser wavelengths of 532 nm and 1064 nm, the best spectral repeatability occurred when the laser wavelength was 355 nm. The relative standard deviation (RSD) of the K I 766.5 nm was only 2.5%. The results indicate that laser wavelength affects the self-absorption effect and spectral stability of LIBS, which means selecting an appropriate laser wavelength can reduce self-absorption and improve stability.
关键词： Laser-induced Breakdown Spectroscopy,Self-absorption,Laser wavelength,Relative standard deviation
更新于2025-09-16 10:30:52
-
Ideal Laser Cooling Efficiency Utilizing Anti-Stokes Luminescence in Yb-Doped Yttrium Aluminum Garnet Powder Crystals; Yb添加イットリウムアルミニウムガーネット結晶粉末におけるアンチストークス発光を利用した理想レーザー冷却効率;
摘要： Laser cooling in rare-earth doped material using anti-Stokes photoluminescence (PL) caused by phonon annihilation realizes novel cooling devices without generating heat and vibration. Yb-doped yttrium aluminum garnet powder crystals, (Y:Yb)AG with the Yb concentration from 2 to 13 mol%, were fabricated by a solid state reaction method. PL of (Y:Yb)AG excited at 659 nm shows the maximum intensity at the Yb concentration of 6 mol% because of concentration quenching of the PL. When we resonantly excite at 1030 nm corresponding to the energy distance between the E5 and E3 levels of the f-f transition of Yb3+, obvious anti-Stoke PL signal has been observed at 968 nm. This result indicates that phonons are absorbed, and, then, an up-converted photon with the energy between the E5 and E1 levels is emitted. The relative cooling efficiency, defined by a product of the ideal cooling efficiency and the integrated PL intensity, becomes maximum at the 1030-nm excitation. The ideal cooling efficiency was estimated to be 1.9% at the Yb concentration of 6 mol% and the 1030-nm excitation at room temperature.
关键词： Self-absorption,Solid state reaction,Phonon absorption,(Y:Yb)AG,Rare-earth,Laser cooling in solids
更新于2025-09-11 14:15:04