Quantitative analysis of analytical elements in Al-In-Sn-O thin film based on comprehensive calibration curves using picosecond laser-induced breakdown spectroscopy.

Al-In-Sn-O (AITO) thin film refers to a novel wide-bandgap transparent conductive material, which is formed by doping the aluminum element into In-Sn-O material. It is of promising application in deep ultraviolet optoelectronic devices. Al/Al+In+Sn and Sn/Al+In+Sn are capable of impacting the optical and electrical properties of AITO thin film. Three groups of AITO thin film samples with different sputtering powers, sputtering pressures, and sputtering times were prepared with magnetron sputtering. The concentration ratio of Al/Al+In+Sn and Sn/Al+In+Sn in AITO samples was quantitatively analyzed with laser-induced breakdown spectroscopy (LIBS) technology. A single calibration curve was drawn based on the sputtering parameters of each group, and the comprehensive calibration curves of two concentration ratios under any sputtering parameters were plotted. The accuracy of the comprehensive calibration curve was determined with samples prepared under random sputtering parameters, and the energy dispersive x-ray spectroscopy analysis results were compared with the LIBS technical analysis results. The relative error was less than 5%, so the LIBS technical analysis was demonstrated to be accurate. By building the comprehensive calibration curve, a novel method to conduct rapid online analysis of AITO thin films and timely determination of photoelectrical properties is presented, and the new application of LIBS technology is developed in thin film semiconductor materials.

All-Inorganic Perovskite CsPb2Br5 Nanosheets for Photodetector Application Based on Rapid Growth in Aqueous Phase.

All-inorganic cesium lead-halide perovskites exhibit a great development prospect in optoelectronic devices owing to their stability and remarkable optoelectronic properties. Herein, we investigate the solution-processed synthesis of perovskite CsPb2Br5 nanosheets by using aqueous and ethanol as solvents. The results show that the aqueous environment ensures the phase formation of CsPb2Br5 and that the supersaturated solution in ethanol boosts nucleation of the nanosheets. The substrate temperature is the key factor for the evolution of morphology and the variation of the thickness of CsPb2Br5 nanosheets. Lower substrate temperature (<35 °C) is conducive to the formation of evenly distributed nanosheets with less stacking. The spatial and time-resolved fluorescence spectra indicate the heterogeneity of the defect density and the recombination process in different nanosheet regions. The photodetector based on the prepared CsPb2Br5 nanosheet displays an excellent switching current ratio (9 × 102), a short rise and decay time (43 and 83 ms, respectively), and good stability (75% of the initial current after 90 days in air). In addition, the mechanical stability and flexibility of the photodetector on the flexible substrate are investigated for 500 bending cycles.

Quantitative toxicological study of dose-dependent arsenic-induced cells via synchrotron-based STXM and FTIR measurement.

Inorganic arsenic (iAs) is a well-known naturally occurring metalloid with abundant hazards to our environment, especially being a human carcinogen through arsenic-contaminated drinking water. The iAs-related contamination is usually examined by a chemical assay system or fluorescence staining technique to investigate iAs accumulation and its deleterious effects. In this work, we present a dual-modality measurement and quantitative analysis methods for the overall evaluation of various dose-dependent iAs-related cytotoxicological manifestations by the combination of the synchrotron-radiation-based scanning transmission soft X-ray microscopy (SR-STXM) and Fourier transform infrared micro-spectroscopy (SR-FTIR) techniques. The gray level co-occurrence matrix (GLCM) based machine learning was employed on SR-STXM data to quantify the cytomorphological feature changes and the dose-dependent iAs-induced feature classifications with increasing doses. The infrared spectral absorption peaks and changes of dose-dependent iAs-induced cells were obtained by the SR-FTIR technique and classified by the multi-spectral-variate principle component analysis (PCA-LDA) method, showing the separated spatial distribution of dose-dependent groups. In addition, the quantitative comparisons of trivalent and pentavalent iAs under high dose conditions (iAsIII_H & iAsV_H) demonstrated that iAsIII_H and its compounds were more toxic than iAsV_H. This method has a potential in providing the morphological and spectral characteristics evolution of the iAs-related cells or particles, revealing the actual risk of arsenic contamination and metabolism.

Rapid qualitative and quantitative analysis of elemental composition of Cu(In, Ga)Se2 thin films using laser-induced breakdown spectroscopy.

The composition of Cu, In, Ga, and Se constituting the Cu(In,Ga)Se2 (CIGS) layer is important for the performance of the thin film. Laser-induced breakdown spectroscopy (LIBS) is very useful in quantitative analysis of elemental composition. In this paper, detection parameters of LIBS were optimized, and the CIGS thin films deposited at different sputtering powers were detected. LIBS results showed that the intensity ratio (Ga/(ln+Ga)) of the analytical spectral line of CIGS film increased initially then reduced with an increase of the sputtering power, and the evolution was consistent with optical bandgaps calculated from the transmission spectra. The intensity ratios of Ga/(ln+Ga) and Cu/(ln+Ga) detected were very highly correlated corresponding to the value obtained from energy dispersive x-ray spectroscopy. All results indicate that it is available and feasible of LIBS to fabricate high-performance CIGS thin film using the one-step radio frequency magnetron sputtering method.

Qualitative and quantitative analysis of an additive element in metal oxide nanometer film using laser induced breakdown spectroscopy.

The photoelectric performance of metal ion-doped TiO2 film will be improved with the changing of the compositions and concentrations of additive elements. In this work, the TiO2 films doped with different Sn concentrations were obtained with the hydrothermal method. Qualitative and quantitative analysis of the Sn element in TiO2 film was achieved with laser induced breakdown spectroscopy (LIBS) with the calibration curves plotted accordingly. The photoelectric characteristics of TiO2 films doped with different Sn content were observed with UV visible absorption spectra and J-V curves. All results showed that Sn doping could improve the optical absorption to be red-shifted and advance the photoelectric properties of the TiO2 films. We had obtained that when the concentration of Sn doping in TiO2 films was 11.89 mmol/L, which was calculated by the LIBS calibration curves, the current density of the film was the largest, which indicated the best photoelectric performance. It indicated that LIBS was a potential and feasible measured method, which was applied to qualitative and quantitative analysis of the additive element in metal oxide nanometer film.

Investigation of the Matrix Effect on the Accuracy of Quantitative Analysis of Trace Metals in Liquids Using Laser-Induced Breakdown Spectroscopy with Solid Substrates.

The detection limit of trace metals in liquids has been improved greatly by laser-induced breakdown spectroscopy (LIBS) using solid substrate. A paper substrate and a metallic substrate were used as a solid substrate for the detection of trace metals in aqueous solutions and viscous liquids (lubricating oils) respectively. The matrix effect on quantitative analysis of trace metals in two types of liquids was investigated. For trace metals in aqueous solutions using paper substrate, the calibration curves established for pure solutions and mixed solutions samples presented large variation on both the slope and the intercept for the Cu, Cd, and Cr. The matrix effects among the different elements in mixed solutions were observed. However, good agreement was obtained between the measured and known values in real wastewater. For trace metals in lubricating oils, the matrix effect between the different oils is relatively small and reasonably negligible under the conditions of our experiment. A universal calibration curve can be established for trace metals in different types of oils. The two approaches are verified that it is possible to develop a feasible and sensitive method with accuracy results for rapid detection of trace metals in industrial wastewater and viscous liquids by laser-induced breakdown spectroscopy.

Quantitative determination of manganese in aqueous solutions and seawater by laser-induced breakdown spectroscopy (LIBS) using paper substrates.

The detection of manganese (Mn) in industrial wastewater and seawater plays an important role in pollution monitoring and the investigation of geochemical and biological processes in the ocean. An approach has been introduced in this work to improve the detection sensitivity of Mn in liquids by laser-induced breakdown spectroscopy with a filter paper as solid substrate. The calibration curves of Mn in aqueous solutions were obtained with the detection of a Czerny-Turner spectrometer and an echelle spectrometer, respectively. The results showed that the Czerny-Turner spectrometer equipped with an intensified charge-coupled device (ICCD) had a more sensitive detection of Mn in aqueous solution with this approach. The limit of detection (LOD) for Mn was down to 0.11 mg/L with laser pulse energy of 90 mJ. With the same approach, the compact echelle spectrometer equipped with an ICCD was used to verify the feasibility for rapid onsite detection. The calibration curves for Mn in simulated industrial wastewater and seawater were constructed to calculate relevant LODs. The LODs of Mn were 2.78 mg/L in mixed solutions and 2.73 mg/L in seawater by calculation. Both the calibration curves and LODs were affected slightly by the matrix effect in the experiment. In order to assess the accuracy, a mixed solution including Mn, Cr, Cd, and Cu with known concentrations was determined, and good agreement between the measured and real values were achieved. It demonstrated that this approach has significant potential for rapid onsite detection of Mn and other metal elements in industrial wastewater and seawater.

[Ultrasonic nebulizer assisted LIBS for detection of trace metal elements dissolved in water].

Because of the complex factors in bulk water, the effect of LIBS on the analysis of liquid sample is limited in liquid sample. Under this circumstances, a new method of LIBS assisted by ultrasonic nebulizing technology has been introduced. According to this method, the liquid sample is transformed into dense droplets by ultrasonic nebulizing technology, and these dense droplets are subjected to the analysis of LIBS later. Based on this thought, a detection experimental system was established, composing of ultrasonic system, 1 064 nm ND: YAG laser, and ICCD system. A series of experiments and analysis were carried out to detect the magnesium element dissolved in pure water using the detection experimental system mentioned above. The results showed that even with a very low laser pulse energy (30 mJ), the signals of LIBS still have a long lifetime and a high signal to background ratio. The limit of detection for magnesium element could reach as low as 0.242 ppm. At the same time, the electron density of plasma was calculated utilizing the Halpha line to give the evolution features of plasma induced by this new method.