Laser-induced breakdown spectroscopy (LIBS) is a quick chemical evaluation device. A strong laser pulse is targeted on the pattern to generate micro-plasma. The component or molecular emission spectra from the microplasma can be utilized to find out the elemental composition of the pattern.
Compared with more conventional strategies akin to atomic absorption spectroscopy and inductively coupled plasma emission spectroscopy (ICP-OES), LIBS has some distinctive benefits: no pattern pretreatment is required, simultaneous multi-element detection and real-time non-contact measurement. These benefits make it appropriate for sensible evaluation of solids, gases and liquids.
Traditional LIBS and growth
Traditional LIBS programs primarily based on nanosecond pulsed lasers (ns-LIBS) have some disadvantages attributable to excessive laser energy intensity, lengthy pulse length and plasma shielding impact. These issues adversely have an effect on its reproducibility and signal-to-noise ratio. Femtosecond LIBS (fs-LIBS) can remove the plasma shielding impact, as a result of the ultra-short pulse length limits the interplay time between the laser and the substance. Femtosecond pulses have excessive energy density, to allow them to successfully ionize and dissociate supplies, ensuing in the next signal-to-noise ratio and more correct spectral decision.
Filament-induced breakdown spectroscopy (FIBS) combines LIBS technology with femtosecond laser filaments. A laser filament is produced by the interplay between Kerr self-focusing and plasma defocusing mechanisms, which exist in the propagation of ultra-short high-intensity beams in clear media (akin to the ambiance). The femtosecond laser filament produces a protracted and secure laser plasma channel, thereby making certain the stability of the laser energy density and bettering the measurement stability. However, when the laser vitality increases, the energy and electron density turn out to be saturated. This is named the laser intensity clamping impact, which limits the detection sensitivity of FIBS.
Fortunately, the laser intensity clamping impact may be overcome by the plasma grating precipitated by the nonlinear interplay of a number of femtosecond filaments. It has been proved that the electron density in the plasma grating is an order of magnitude increased than the electron density in the filament.
Based on this perception, researchers led by Professor Zeng Heping from East China Normal University in Shanghai not too long ago demonstrated a brand new technology: plasma grating induced breakdown spectroscopy (GIBS). GIBS can successfully overcome the shortcomings of ns-LIBS, fs-LIBS and FIBS. Using GIBS, the signal intensity is elevated by more than three times, and the plasma lifetime induced by the plasma grating is roughly twice that of FIBS beneath the identical preliminary pulse. Since there isn’t a plasma shielding impact, excessive energy and electron density of femtosecond plasma grating, quantitative evaluation is possible.