Spatially-offset double-pulse laser-induced breakdown spectroscopy: A novel technique for analysis of thin deposited layers

A novel technique, spatially-offset double-pulse laser-induced breakdown spectroscopy (SODP-LIBS), is invented for analysis of thin layers. In this technique, two laser spots are spatially offset by a few mm, while there is no spatial gap for the standard collinear DP-LIBS. It is demonstrated from analysis of thin W layers (∼30–250 nm thickness) deposited on Mo substrates at a reduced ambient pressure of ∼ 5 × 10⁻³ Torr that (1) the W I signal intensity is enhanced with SODP-LIBS and (2) a clearer transition between W and Mo is obtained with SODP-LIBS, compared to the standard DP-LIBS. - Highlights: • Spatially-offset double-pulse (SODP) LIBS is invented for analysis of thin layers. • A spatial offset by a few mm between two laser spots is the key in this technique. • It is demonstrated that SODP-LIBS is superior to the standard collinear DP-LIBS.