Femtosecond Laser Filament Nonlinear Interactions Inducing Breakdown Spectroscopy

The research team at the State Key Laboratory of Microspectroscopy of East China Normal University has made a major breakthrough in the field of ultrafast laser-induced avalanche spectroscopy technology.

The team recently proposed plasma-induced plasma-induced breakdown spectroscopy (GIBS) and multidimensional plasma-induced breakdown spectroscopy (MIBS) techniques, confirming that these new methods show high levels of sensitivity to the traditionally used LIBS and filament-induced breakdown spectroscopy (FIBS) . ).

Substrate effects and plasma shielding interference usually plague nanosecond laser-induced breakdown spectrometers. On the other hand, the filament-induced breakdown spectroscopy is limited by peak energy limitations, which makes the sensitivity difficult to improve. To overcome these hurdles, the research team first developed an avalanche spectroscopy technique produced by plasma gratings.

By using two nonlinearly interconnected filament pulses, this method forms a plasma lattice to overcome maximum energy limitations and enhance the electronic density of the excitation, allowing a quantum leap in sensitivity and overcoming interference from the plasma shielding effect.

To enhance the excitation effect, the research team went on to propose a multidimensional plasma grating-induced avalanche spectroscopy technique. This method uses three non-overlapping, non-coplanar femtosecond pulses that interact with the sample to generate a plasma lattice. The team successfully observed the diffraction effect of the plasma lattice, progressing from one to two dimensions.

The periodic structure and high-level nonlinear effects of the two-dimensional plasma lattice greatly enhanced the plasma density and energy density, which raised the sensitivity of the avalanche spectroscopy detection technique to a higher level. The research team also discovered that the spectral line signal obtained by the MIBS technology is enhanced with increasing laser power, reaching more significant advantages when the energy of a single pulse exceeds 2 mJ.

Moreover, MIBS technology only requires modifications to the excitation source without introducing complex sample preparation steps or additional equipment, while retaining the fast, simple and convenient advantages of LIBS technology, making it able to meet on-site and real-time detection needs in specific scenarios.

Based on the outstanding results achieved with multi-beam pulsed laser coupling, a novel combination of filament-induced avalanche spectroscopy and plasma grid-induced avalanche spectroscopy (F-GIBS) was proposed specifically for solution detection.

By reasonably adjusting the effect delay between the filament and the plasma grid, the double excitation effect of solution detection was achieved, overcoming the bubble and splashing problems encountered by avalanche spectroscopy in solution detection, and improving the sensitivity and accuracy of solution detection.

With the development and application of GIBS/MIBS/F-GIBS technologies, it has become possible to adapt to mobile operations in harsh field conditions and to achieve online offline on-site detection. These technologies are expected to find wide applications in areas such as mineral exploration, environmental monitoring, water sciences, and life sciences.

The results have been published in the journal High speed science.