Minimally destructive and multi-element analysis of steel alloys by argon fluoride laser-induced plume emissions

A minimally destructive and multi-element analysis of steel alloys by argon fluoride laser-induced plume emissions was reported. The Nd: YAG laser pulse was directed normally onto the flat surface of the target cylinder, which was rotating about its axis of symmetry. The pulse energy was typically 120μJ and fluence was about 6 J cm^-2. The ArF laser pulses was focused to a 2 mm diameter spot at the plane of the plume, and barely irradiated the target surface. Plume emissions were collected along the longitudinal direction but slightly tilted up to avoid the reflected 193 nm light. The ablated surface was inspected under the optical microscope and correlated with the photoacoustic signal. It was observed that the ArF enhanced analyte emissions were synchronous with the ArF pulse and the continuum background was dim, both indicative of laser excited atomic fluorescence (LEAF).