Plasma characterization of brass alloys by laser induced breakdown spectroscopy

摘要

Laser-induced breakdown spectroscopy (LIBS) has been shown to be a useful technique in elemental analysis with many advantages including rapid analysis, simultaneous multi-element detection, in-situ or stand-off analysis capability. To evaluate the potential application of LIBS for quantitative analysis, some experimental investigations into the laser induced plasma process were undertaken with brass alloy sample, in the laboratory. The plasma was generated by a Q-switched Nd:YAG laser operating at 532 nm with pulse width of 10ns and repeat frequency of 10 Hz. The LIBS signal was coupled to the spectrometer and recorded with OMA system and a PMT in conjunction with a computer controlled Boxcar integrator. The temporal characteristic of the plasma was investigated with the emission line of Cu atom at 324.75 nm, 327.40 nm and the emission line of Zn atom at 330.25 nm. The optimum delay time range for 324.75 nm from Cu atoms and 330.25 nm from Zn atoms is from 300 to 600 ns. The self-absorption of Cu atomic lines at 324.75 nm and 327.40 nm can be reduced by increasing the laser energy and recording the spectra in the early stage of the plasma formation. The experimental results are effective for improving the slope of calibration curve.