Two-step laser desorption/photoionization mass spectrometry (L2MS) represents a powerful tool for the organic analysis of astromaterials. The technique has high sensitivity and requires little to no sample preparation.

The JSC ultra-L2MS is a one-of-a-kind instrument designed to measure organic matter in complex geological and biological samples. In its original configuration, the ultra-L2MS two-photon UV (ultraviolet) ionization source could detect aromatic molecules with extremely high sensitivity with negligible fragmentation. How ever, it had limited sensitivity to non-aromatic organics.

A coherent far-UV photon source was developed for the ultra-L2MS that enables ionization and detection of nearly all classes of organic molecules. Coherent vacuum ultraviolet (VUV) radiation is generated by a Xe-Ar phasematched tripling cell. The tripling cell was incorporated into the ultra-L2MS system as a VUV ionization source. This instrument is capable of measuring organic molecules on the surfaces of samples at spatial scales to 5 micrometers without the need for any significant sample preparation. Tests of the instrument show that molecules are generally ionized without significant fragmentation, facilitating identifying species in mass spectra of complex samples.

The modified instrument is now able to measure diverse ranges of organic species at sub-femtomole sensitivities (<10–18 mole) with micrometer spatial resolution. The modified instrument will be unique and be capable of measuring a wide range of organic molecules with an unprecedented combination of sensitivity and spatial resolution.

This work was done by Scott Messenger and Simon Clemett of Johnson Space Center. MSC-25283-1