Femtosecond laser-induced breakdown spectroscopy (fs-LIBS) is employed to detect tiny amounts of mass ablated from macroscopic specimens and to measure chemical images of microstructured samples with high spatial resolution. Frequency-doubled fs-pulses (length 400 fs, wavelength 520 nm) are tightly focused with a Schwarzschild microscope objective to ablate the sample surface. The optical emission of laser-induced plasma (LIP) is collected by the objective and measured with an echelle spectrometer equipped with an intensified charge-coupled device camera. A second fs-laser pulse (1040 nm) in orthogonal beam arrangement is reheating the LIP. The optimization of the experimental setup and measurement parameters enables us to record single-pulse fs-LIBS spectra of 5 nm thin metal layers with an ablated mass per pulse of 100 femtogram (fg) for Cu and 370 fg for Ag films. The orthogonal double-pulse fs-LIBS enhances the recorded emission line intensities (two to three times) and improves the contrast of chemical images in comparison to single-pulse measurements. The size of ablation craters (diameters as small as 1.5 µm) is not increased by the second laser pulse. The combination of minimally invasive sampling by a tightly focused low-energy fs-pulse and of strong enhancement of plasma emission by an orthogonal high-energy fs-pulse appears promising for future LIBS chemical imaging with high spatial resolution and with high spectrochemical sensitivity.

飞秒激光诱导击穿光谱 (fs-LIBS) 用于检测从宏观样品中烧蚀的微量质量，并以高空间分辨率测量微结构样品的化学图像。倍频 fs 脉冲（长度 400 fs，波长 520 nm）通过 Schwarzschild 显微镜物镜紧密聚焦以烧蚀样品表面。激光诱导等离子体 (LIP) 的光发射由物镜收集，并用配备有增强型电荷耦合器件相机的阶梯光谱仪进行测量。正交光束排列中的第二个飞秒激光脉冲 (1040 nm) 正在重新加热 LIP。实验设置和测量参数的优化使我们能够记录 5 nm 薄金属层的单脉冲 fs-LIBS 光谱，每脉冲烧蚀质量为 100 飞克 (fg) 和 370 fg 的银膜。与单脉冲测量相比，正交双脉冲 fs-LIBS 增强了记录的发射线强度（两到三倍）并提高了化学图像的对比度。第二个激光脉冲不会增加烧蚀坑的大小（直径小至 1.5 µm）。通过紧密聚焦的低能 fs 脉冲进行微创采样和通过正交高能 fs 脉冲强烈增强等离子体发射的组合，对于未来具有高空间分辨率和高光谱化学灵敏度的 LIBS 化学成像来说似乎是有希望的。与单脉冲测量相比，正交双脉冲 fs-LIBS 增强了记录的发射线强度（两到三倍）并提高了化学图像的对比度。第二个激光脉冲不会增加烧蚀坑的大小（直径小至 1.5 µm）。通过紧密聚焦的低能 fs 脉冲进行微创采样和通过正交高能 fs 脉冲强烈增强等离子体发射的组合，对于未来具有高空间分辨率和高光谱化学灵敏度的 LIBS 化学成像来说似乎是有希望的。与单脉冲测量相比，正交双脉冲 fs-LIBS 增强了记录的发射线强度（两到三倍）并提高了化学图像的对比度。第二个激光脉冲不会增加烧蚀坑的大小（直径小至 1.5 µm）。通过紧密聚焦的低能 fs 脉冲进行微创采样和通过正交高能 fs 脉冲强烈增强等离子体发射的组合，对于未来具有高空间分辨率和高光谱化学灵敏度的 LIBS 化学成像来说似乎是有希望的。5 µm) 不会因第二个激光脉冲而增加。通过紧密聚焦的低能 fs 脉冲进行微创采样和通过正交高能 fs 脉冲强烈增强等离子体发射的组合，对于未来具有高空间分辨率和高光谱化学灵敏度的 LIBS 化学成像来说似乎是有希望的。5 µm) 不会因第二个激光脉冲而增加。通过紧密聚焦的低能 fs 脉冲进行微创采样和通过正交高能 fs 脉冲强烈增强等离子体发射的组合，对于未来具有高空间分辨率和高光谱化学灵敏度的 LIBS 化学成像来说似乎是有希望的。