Current Progress in Femtosecond Laser Ablation/Ionisation Time-of-Flight Mass Spectrometry

Abstract

The last decade witnessed considerable progress in the development of laser ablation/ionisation time-of-flight mass spectrometry (LI-TOFMS). The improvement of both the laser ablation ion sources employing femtosecond lasers and the method of ion coupling with the mass analyser led to highly sensitive element and isotope measurements, minimisation of matrix effects, and reduction of various fractionation effects. This improvement of instrumental performance can be attributed to the progress in laser technology and accompanying commercialisation of fs-laser systems, as well as the availability of fast electronics and data acquisition systems. Application of femtosecond laser radiation to ablate the sample causes negligible thermal effects, which in turn allows for improved resolution of chemical surface imaging and depth profiling. Following in the footsteps of its predecessor ns-LIMS, fs-LIMS, which employs fs-laser ablation ion sources, has been developed in the last two decades as an important method of chemical analysis and will continue to improve its performance in subsequent decades. This review discusses the background of fs-laser ablation, overviews the most relevant instrumentation and emphasises their performance figures, and summarizes the studies on several applications, including geochemical, semiconductor, and bio-relevant materials. Improving the chemical analysis is expected by the implementation of laser pulse sequences or pulse shaping methods and shorter laser wavelengths providing current progress in mass resolution achieved in fs-LIMS. In parallel, advancing the methods of data analysis has the potential of making this technique very attractive for 3D chemical analysis with micrometre lateral and sub-micrometre vertical resolution.

Peptide Mass Spectra from Micrometer-Thick Ice Films Produced with Femtosecond Pulses

“…The interaction between biomolecules and the substrate surface with femtosecond pulses generally differs from that of nanosecond pulses. , The heat-affected zone produced after laser pulse impact is proportional to the square root of the pulse duration . For low-intensity femtosecond pulses, this phenomenon is even more negligible. , Our experiment supports that laser-induced heat zones were barely visible under experimental conditions, while only higher pulse energies caused typical heat-induced patterns on the silicon coverslip (Figure S14). Nevertheless, laser-induced temperature rise and the thinning of the ice film might interact beneficially and promote bradykinin desorption.…”

“…45 For low-intensity femtosecond pulses, this phenomenon is even more negligible. 46,47 Our experiment supports that laser-induced heat zones were barely visible under experimental conditions, while only higher pulse energies caused typical heat-induced patterns on the silicon coverslip (Figure S14). Nevertheless, laser-induced temperature rise and the thinning of the ice film might interact beneficially and promote bradykinin desorption.…”

High Mass Resolution fs-LIMS Imaging and Manifold Learning Reveal Insight Into Chemical Diversity of the 1.88 Ga Gunflint Chert

“…Laser ablation/ionization mass spectrometry (LIMS) is a promising surface characterization method that has recently experienced a revival and a wave of modernization (Azov et al, 2020;Tulej et al, 2021a). Modern laser ablation/ ionization time-of-flight mass spectrometers (LIMS) are capable of providing element and isotope characterization of the investigated spots in the ablation/ionization regime (Huang et al, 2011;Riedo et al, 2013b;Tulej et al, 2021b) and molecular characterizations in the desorption regime (Cui et al, 2013;Moreno-García et al, 2016;Ligterink et al, 2020).…”

Chemical identification of microfossils from the 1.88‐Ga Gunflint chert: Towards empirical biosignatures using laser ablation ionization mass spectrometer

“…7,23,30 The time-of-flight mass analyzer works in the positive ion detection mode and provides a single unit mass resolution and a ppm-level sensitivity. For the detailed characterization of the instrument and method in general, we refer the interested reader to the reviews 43,44 and technical reports describing figures of merit. 21,23,45,46 In the current laboratory setup, a mass spectrometer is accompanied by an integrated microscopy system 12 and a fs UV-258-nm ionization source.…”