UV fs–ns double-pulse laser induced breakdown spectroscopy for high spatial resolution chemical analysis

Abstract

We study the use of an ultraviolet (UV) femtosecond (fs)–nanosecond (ns) double-pulse scheme to improve the analytical capabilities of Laser Induced Breakdown Spectroscopy (LIBS) in the few-micron (<2 μm) spatial resolution regime. We show that a double-pulse orthogonal configuration can enhance the spectral emission intensity by roughly 360 times as compared to a single-fs laser pulse LIBS of silicon (Si). Although the spectral emission lifetime in single-pulse LIBS is less than 20 ns, the second pulse provides signal enhancement hundreds of nanoseconds later, indicating that a significant number of non-radiative species (neutrals and/or particles) exist in these small length-scale plasmas long after the fs-laser pulse is over. The double-pulse configuration is a practical way to improve the limits of detection of LIBS for micron/submicron spatial resolution.