Abstract For laser-induced fluorescence (LIF), the SNR and related concentration detectability was severely limited by background signal (noise). Herein, an axial-excitation LIF based on pinhole metal-capillary (PMC) and direct laser-diode excitation was proposed. An overall ~480 fold improvement on SNR was realized, because the laser-sidewall interaction (LSI) and related background signal (noise) can be effectively suppressed in PMC by avoidance of laser leakage and laser contact with capillary sidewall. For rhodamine B detection without sample enrichment, a detection limit of concentration (DLC) of 0.4 pM was obtained, which is 2.5 fold lower than the DLC (1 pM) of commercial LIFs equipped with bulky and expensive Ar+ laser. For selective detection of Cu2+, a DLC of 5 pM was realized, which is more than 40 fold lower than that of previous fluorimetry detection with similar quantum-dot probe. The PMC-LIF features compact (16 × 4 × 4 cm3), low-cost and high concentration detectability.

中文翻译：

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基于针孔金属毛细管和直接激光二极管激发的紧凑、低成本和高灵敏度 LIF

摘要 对于激光诱导荧光 (LIF)，SNR 和相关浓度检测能力受到背景信号（噪声）的严重限制。在此，提出了一种基于针孔金属毛细管 (PMC) 和直接激光二极管激发的轴向激发 LIF。实现了 SNR 整体约 480 倍的改进，因为通过避免激光泄漏和激光与毛细管侧壁的接触，可以在 PMC 中有效抑制激光侧壁相互作用 (LSI) 和相关背景信号（噪声）。对于没有样品富集的罗丹明 B 检测，获得了 0.4 pM 的浓度检测限 (DLC)，比配备庞大且昂贵的 Ar+ 激光器的商用 LIF 的 DLC (1 pM) 低 2.5 倍。为了选择性检测 Cu2+，实现了 5 pM 的 DLC，这比以前使用类似量子点探针的荧光法检测低 40 倍以上。PMC-LIF 具有紧凑 (16 × 4 × 4 cm3)、低成本和高浓度可检测性。