Fig. 2.
The histogram of D/H ratio is compared with variations in 12CH3−/12C− ionic ratios. Steps of 100‰ rank the δD values. (A) Histogram of the isotopic compositions of CH4 plasma deposited IOM. The shaded central area represents ≥99% of the sample surface with a domain a variation defined by 2 sigma error (±110‰) around the mean D/H ratio (R0) defining δDIOM = 0‰ {δDIOM (‰) = [(R/R0) − 1] × 1,000 with R = D/H}. The curve of the density distribution highlights the five modes of the isotopic pattern. (B) The 12CH3−/12C− ratios are reported versus δD values. The bulk atomic H/C sample value determined by elemental analyses is 1.34. Error bars on 12CH3−/12C− stand for the statistical error, and the 100‰ bars on δD values stand for the width of the step (the +250‰ data point is not reported because of its large errors on the 12CH3−/12C− ratio).