Nine samples of the cometary analogue material were analysed. Typical sample size after irradiation and before warming up (i.e. solid residue plus trapped residual methane and/or methane derived volatile gases) was moles. After oxidation, all the carbon of the solid residues was converted into the form of CO2 the amounts varied in the range 0.27 to moles.
Carbon isotopic composition for the organic matter are reported in Table 1 and expressed in units defined as follows:
with and as 13 C/12 C ratios for the sample and the PDB (Pee Dee Belemnite Standard) respectively (13 C/12 C = 0.0112372). The isotopic composition of the CH4 before irradiation was . The carbon isotopic composition of the samples varied from -25 to -35. Several samples were analysed in triplicate and give a reproducibility on C of (2 standard deviations).
Table 1. Isotopic composition of carbon in solid residues. values are expressed in relatively to PDB and quantities in moles. These values are not blank corrected.
The blank contribution was determined to lie between 0.32 and moles, with carbon isotopic compositions of between -27.95 and -27.87, respectively. The two blanks correspond to analyses of the platinum foil and of the silicon wafer sealed in the platinum.
© European Southern Observatory (ESO) 1998
Online publication: January 27, 1998