Enhancing laser ablation inductively coupled plasma mass spectrometry analysis through empirical modeling of crater geometry

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) systems are engineered to produce uniform, flat-top beam profiles for optimal surface sampling. In practice, however, rounder beam profiles are prevalent. Their geometrical characteristics can be mathematically described using the two-dimensional super-Gaussian or even a Gaussian function for smaller beam sizes, with the super-Gaussian factor ( n ) serving as a quantifier. Since the beam profile and the ablation grid have a direct influence on the amount of sampled surface material, the idea is to reduce the ablation grid by sub-pixel mapping to improve the accuracy of surface scanning, increase pixel density, improve spatial resolution, and increase signal-to-noise ratio (SNR). This paper explores the relationship between super-Gaussian order ( n ), beam size, and laser fluence for circular beams, using two laser ablation systems with different wavelengths – 193 nm and 213 nm nanosecond lasers. An empirical model was developed to yield the factor n , facilitating the determination of the contraction factor ( k ). Identifying the precise contraction factor for each beam size brings the beam profile closer to a flat-top shape, producing smoother post-ablation surfaces and enhancing image quality due to heightened pixel density. Ultimately, such models improve our understanding of crater geometry optimization, leading to better analytical outcomes in LA-ICP-MS analysis. • 193 nm and 213 nm nanosecond lasers were used to explore the relationship between super-Gaussian order, beam size, and laser fluence. • A novel empirical model that generates the super-Gaussian (n) order was developed. • Determining the exact super-Gaussian order allows for geometry optimization, ultimately resulting in smoother post-ablation surfaces and improved image quality.