Boosting Signal Intensity in Glow Discharge Optical Emission Spectroscopy via Magnetic Field Confinement

A novel magnetic field confinement approach was developed to enhance signal intensity in glow discharge optical emission spectrometry (GDOES). Among the 12 fabricated magnet configurations, the C-1-N52 design yielded the most substantial improvement, enhancing signal intensity by 45.3-fold for Al I 396.152 nm in an Al sample and by 48.7-fold for Cu I 324.755 nm in Fe-Ni-Cr alloy SRM 1247, compared to conventional nonmagnet operation. The method was validated using Al, Ta, In, SiC, AlN, GaN, and four NIST-certified reference materials, demonstrating a significant improvement in sensitivity for elements including Al, Cr, Mn, Mo, Fe, Ti, Ni, Ag, Cu, Co, S, P, and C. Notably, the detection limit (LOD) for Cu I 324.755 nm with C-1-N52 was reduced from 2.24 μg g^-1 to 0.04 μg g^-1, surpassing the performance of the nonmagnet system. Mechanism studies based on Stark broadening plots revealed that the magnetic field increased the electron density (n_e) from (3.19 ± 0.04) × 10¹⁶ cm^-3 to (3.83 ± 0.05) × 10¹⁶ cm^-3 with respect to nonmagnet operation, thus improving the collision efficiency. COMSOL simulations and SEM characterization of Ar⁺-etched GaN surfaces further confirmed consistent axial gradient distributions for electrons and Ar⁺ ions, which significantly increased the number of collisions between sample atoms and electrons. The overall GDOES signal enhancement is therefore attributed to the synergistic effect of increased electron density and magnetically optimized spatial confinement, which collectively boost plasma collision-excitation efficiency. This work establishes a powerful new strategy for boosting GDOES sensitivity and offers a promising approach for analyzing high-purity advanced materials.