Laser Ablation Electrospray Ionization Mass Spectrometry Imaging (LAESI-MSI) Using an Er:YAG Laser for Improved Spot Size Resolution and Tunable Ablation
Laser ablation electrospray ionization mass spectrometry imaging (LAESI-MSI) is an ambient ionization technique used for direct analysis of biological samples. Traditionally, LAESI-MSI has employed Nd:YAG-based lasers that use optical parametric oscillator (OPO) crystals to convert 1064nm wavelength light into the mid-IR region, which is tuned to the 2940nm wavelength via a nonlinear crystal. The design complexity of OPO lasers leads to higher costs, reduced robustness, and large footprints. In this work, a new Er:YAG laser that emits light directly at 2940nm was integrated into a LAESI-MSI system (Figure 1), and its performance compared against OPO-based systems. The operational flexibility of Er:YAG lasers provide a broad range of output energy and pulse duration, which enable tunable ablation characteristics and improved spot size resolution.