Novel optical gas-sensing materials for Au nanoparticle (NP)-modified ZnO nanorod (NR) arrays were fabricated using hydrothermal synthesis and magnetron sputtering on Si substrates. The optical performance of ZnO NR can be strongly modulated by the annealing temperature and Au sputtering time. With exposure to trace quantities of oxygen, the ultraviolet (UV) emission of the photoluminescence (PL) spectra of Au/ZnO samples at ~390 nm showed a large variation in intensity. Based on this mechanism, ZnO NR based oxygen gas sensing via PL spectra variation demonstrated a wide linear detection range of 10–100%, a high response value, and a 1% oxygen content sensitivity detection limit at 225 °C. This outstanding optical oxygen-sensing performance can be attributed to the large surface area to volume ratio, high crystal quality, and high UV emission efficiency of the Au NP-modified ZnO NR arrays. Density functional theory (DFT) simulation results confirmed that after the Au NPs modified the surface of the ZnO NR, the charge at the interface changed, and the structure of Au/ZnO had the lowest adsorption energy for oxygen molecules. These results suggest that Au NP-modified ZnO NR are promising for high-performance optical gas-sensing applications.

Laser ablation has been extensively studied by researchers due to its high precision, high efficiency processing capabilities, and wide range of application potentials. However, in a vacuum environment, due to the complexity of experimental conditions, specific application scenarios, and interdisciplinary interferences, more in-depth research on the ablation behavior of high-intensity lasers in vacuum is still insufficient. In response to such issues, experiments were conducted on titanium alloy perforation using a nanosecond laser in a vacuum environment. The variations in ablation depth and volume as functions of pulse energy, pulse number, and defocus were investigated. Both the depth and volume ablation efficiencies were calculated, and the three-dimensional morphology of the ablation holes was captured. Additionally, the ablation plume was observed to support the research conclusions. The results indicate that within the number of high-intensity laser pulses, the ablation depth per pulse can be increased by more than four times, and the average ablation volume per pulse can reach 0.97 µm³/µJ. The enhanced sputtering of molten material during the multi-pulse laser ablation process in a vacuum environment is identified as the primary factor contributing to the increased ablation efficiency. With the advancement of science and technology and the growing demand for applications, this research is crucial for the further development of fields such as space exploration and technology, advanced manufacturing technology, and basic scientific research.

In this study, electrodeposition (ED) combined with a spark discharge-facilitated laser-induced breakdown spectroscopy—referred to as SD-LIBS—was employed for highly sensitive detection of trace chromium (Cr) in aqueous solutions. First, trace Cr ions in water were preconcentrated on the outer surface of an ultra-pure aluminum base by ED, effectively addressing the issue of poor detection sensitivity when LIBS is applied directly to liquid samples. Subsequently, SD-LIBS was employed for the analysis of the chromium (Cr) deposited on the aluminum (Al) exterior, where the spark discharge significantly enhanced the emission intensities of the Cr (I) spectral lines centered at 425.43 nm, 427.48 nm, and 428.90 nm. Based on the calibration curves obtained from standard solutions, the limits for the detection (LoD) with respect to chromium (Cr) under different discharge voltages were determined. With the elevation of discharge voltage over the 0–2 kV range, the LoDs of the neutral chromium (Cr) line I corresponding to 425.43 nm and 428.90 nm, the concentration levels of 3.86 n and 5.13 ng decreased to 1.19 ng and 1.57 ng, respectively, with all values referenced per milliliter. These results demonstrate that spark discharge further improves the detection sensitivity of LIBS in aqueous environments. Overall, the combined ED+SD-LIBS approach exhibits excellent analytical performance for trace metal detection in water, offering promising potential for water quality monitoring applications.

This study systematically investigates the dynamic evolution of chemical regimes in pulsed coaxial dielectric barrier discharge (DBD) plasma under atmospheric pressure using mass spectrometry. An innovative real-time mass spectrometric monitoring methodology was established, enabling the dynamic tracking of the formation and consumption processes of key reactive species such as ozone (O₃) and nitrogen oxides (NO_x). Energy density was the critical parameter governing the evolution of gaseous chemical components, with a quantitative elucidation of the regulatory mechanisms of air flow rate and control voltage on plasma chemical regime transition kinetics. Experimental results revealed significant parametric correlations: Under a constant control voltage of 140 V, increasing the gas flow rate from 0.5 to 5.5 L/min prolonged the transition duration from O₃-NO_x coexistence regime to a NO_x-dominant regime from 408 s to 1210 s. Conversely, at a fixed flow rate of 3.5 L/min, elevating the control voltage from 120 V to 140 V accelerated this transition, reducing the required time from 2367 s to 718 s. Parametric sensitivity analysis demonstrated that control voltage exerts approximately 3.3 times greater influence on transition kinetics than flow rate variation. Through comprehensive analysis of the formation and consumption mechanisms of N, O, O₃, and NO_x species, we established a complete plasma chemical reaction network. This scheme provides fundamental insights into reaction pathways while offering practical optimization strategies for DBD systems. For aerospace applications, this work holds particular significance by demonstrating that the identified control parameters can be directly applied to plasma-assisted treatment of propellant wastewater at launch sites, where the efficient removal of nitrogen-containing pollutants is crucial. These findings advance both the fundamental understanding of atmospheric-pressure plasma chemistry and the engineering applications of plasma-based environmental remediation technologies in aerospace operations.

The detection and quantification of gases in mixed or specific environments are critical across a broad range of fields, such as life sciences, environmental monitoring, food preservation, vacuum technology, the automotive and chemical industries, aerospace engineering, and underwater operations. In many practical scenarios, real-time dynamic monitoring of gases across a wide concentration range is especially essential. Over recent decades, substantial efforts have been directed toward the development of advanced gas sensors. Among these, photoluminescence (PL)-based optical sensing has attracted increasing attention due to its distinct advantages over conventional electrical methods. These benefits include high accuracy and sensitivity, good reversibility, noninvasive and remote operation, no reliance on electrical contacts, ease of miniaturization, simple fabrication, and compatibility with strong electromagnetic environments. Therefore, this chapter focuses on zinc oxide nanorod arrays as the subject of study, further summarizing and analyzing the construction methods of optical sensing chips and their applications in gas sensing.