Rapid and accurate detection of nitrite in the aqueous environment is extremely important for ecological safety and human health. In this paper, the Raman detection of nitrite by a NiFe₂O₄@Ag sensor in water is enhanced by an extra magnetic field collaborated with surface plasma. Most importantly, it is demonstrated that the magnetic field enhances the Raman peak intensity through not only the effect of magnetic aggregation but also the magnetic field-induced dielectric polarization effect. In this way, the NO₂⁻ can be detected in a wide linear range from 10⁻⁸ to 10⁻³ mol L⁻¹, and the limit of detection (LOD) can reach as low as 1.25 × 10⁻⁹ mol L⁻¹, which is 5.69 times lower than that in the absence of an external magnetic field. Similarly, the sensitivity under the magnetic field is 2.65 times that without the magnetic field. In addition, the sensor also shows superior detection ability to NO₂⁻ in real samples. Given the excellent capability of the magnetic field-enhanced Raman spectra, the reported strategy offers new thoughts on how to enhance the detection ability by an external magnetic field and show the great application potential in real water bodies.

中文翻译：

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磁场诱导介电极化增强 NiFe2O4@Ag 对亚硝酸盐的拉曼检测


快速、准确地检测水环境中的亚硝酸盐对于生态安全和人类健康极为重要。在本文中，通过与表面等离子体配合的额外磁场增强了NiFe ₂ O ₄ @Ag传感器对水中亚硝酸盐的拉曼检测。最重要的是，证明磁场不仅通过磁聚集效应而且通过磁场诱导的介电极化效应增强拉曼峰强度。这样，NO ₂ ^-可以在10 ^-8至10 ^-3 mol L ^{-1 的}较宽线性范围内检测到，检测限（LOD）可低至1.25 × 10 ^-9 mol L ^{- 1} ，比无外磁场时低5.69倍。同样，磁场下的灵敏度是无磁场下的2.65倍。此外，该传感器还对实际样品中的NO ₂ ^-表现出优异的检测能力。鉴于磁场增强拉曼光谱的优异性能，该策略为如何增强外部磁场的检测能力提供了新的思路，并在实际水体中展现出巨大的应用潜力。