H218O Tunable Diode Laser Paleothermometer for Determining Climate Change on Earth and Mars

C.R. Webster (PI), G.J. Flesch, M. Hecht, and F. Carsey

 

We have designed and built a miniature near-IR tunable diode laser spectrometer for measuring in situ the isotopic fractionation delta-18O in water samples from ice cores of either Earth or Mars.  The H218O/ H216O laser paleothermometer uses a thermoelectrically-cooled single-mode DFB tunable diode laser (TDL) in the near-IR region at 1.88 mm to scan over selected vibration-rotation lines of H218O and H216O.  A working prototype weighing only 220 g has been built with electronics based on the Motorolla HC-12 microcontroller, and has been used to generate spectra whose analysis demonstrates sensitivities of delta-18O of 0.2 per mil precision and 1 per mil absolute accuracy.
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