Method and apparatus for quantitative chemical analysis of liquid metals and alloys

A method of measuring one or more elements in a liquid metal or alloy sample with Laser Induced Breakdown Spectroscopy (LIBS), comprising:

• providing a sample of the liquid metal or alloy to be analysed,
• placing an instrument head above the sample surface wherein the instrument head comprises laser excitation optics that are arranged to receive and focus transmitted light from a pulsed excitation laser, receiving optics for receiving emission from the sample, an open-bottom chamber through which the laser excitation optics guide laser light, the open-bottom chamber extending upwardly from a substantially flat bottom surface of the instrument head,
• positioning said instrument head above the sample surface such that said laser excitation optics focus pulses from the excitation laser to a focal point which is at a distance below the sample surface which is more than one Rayleigh length of the focused laser beam,
• emitting one or more laser pulses on the sample through the excitation optics with sufficient optical energy to ablate a fraction of the sample volume and create a plasma above the liquid metal,
• receiving emitted light through the receiving optics from the generated plasma and transmitting to a detector for recording spectral data for the detected light,
• analysing the spectral data to obtain quantitative determination of one or more elements.