ChemLIBS Laser Spectrometer

The Mount Holyoke LIBS instrument was designed to be analogous to the ChemCam flight instrument.It was designed and built in the LIBS User Facility at LANL.The instrument has three Ocean Optics HR2000+ user-configured spectrometers and a Quantel Ultra100 laser operating at 1064 nm, up to 15 mJ/pulse, 10 Hz, with a 6-ns pulse width.

An attenuator is permanently integrated into the laser, allowing power density to be varied to obtain data that match those acquired on Mars (~2 GW/cm2).A 12-inch cube vacuum chamber houses the sample tray (Figure 1).Samples are analyzed under a 7-Torr CO2 atmosphere.

Standard protocol is to analyze every sample with the spectrometer exposure time set to 1 s, recording plasma emission for 10 laser shots.Five of these exposures are averaged for each sample spot probed, so each probed spot represents 50 laser shots.Five different spots on each pressed pellet are sampled to account for heterogeneity in our powdered samples, so there are 250 laser shots for each sample.Data are collected in UV, VIS, and VIS/near-IR wavelength ranges.

This instrument forms the basis for data used to understand results from the ChemCam instrument on the Curiosity rover on Mars.