A small high‐irradiance laser ionization time‐of‐flight mass spectrometer

Abstract

A small high-irradiance laser ionization time-of-flight mass spectrometer (LI-TOFMS) with orthogonal sample introduction was described. High irradiance of 6 x 10(10) W/cm(2) at 532 nm from a Nd:YAG laser was applied in the experiment to get a high ionization degree in plasma and to dissociate the interferential polyatomic ions. Meanwhile, the interferential multiply charged ions resulted by high-irradiance were nearly eliminated in the spectrum by utilizing helium as the buffer gas in the ion source due to three-body recombination, which resulted in a relatively clean background. Improved signal stability was obtained by automated step moving of the sample stage in short time intervals. By using two sets of Einzel lens in transport system, nearly uniform relative sensitivity coefficients (RSCs) were achieved for most of metal elements including light ions which were detected in extremely low sensitivity in previous hexapole transportation instrument. The resolving power reaches 2200, and the detection limits (DLs) are 10(-6) g/g for metal elements in the steel standard.