[1] Rice Univ, Dept Geol & Geophys, Houston, TX 77251 USA
[2] Rice Univ, Dept Chem, Houston, TX 77251 USA
[3] Rice Univ, Rice Quantum Inst, Houston, TX 77251 USA
[4] Soc Lupi Chem Inst, I-00133 Rome, Italy
[5] Univ Amsterdam, Inst Mass Spectrometry, NL-1018 WS Amsterdam, Netherlands
[6] Free Univ Amsterdam, Dept Phys & Astron, NL-1081 HV Amsterdam, Netherlands