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Numbers designated in boldface are the main mass fragments; a.m.u. atomic mass unit

Numbers designated in boldface are the main mass fragments; a.m.u. atomic mass unit light. A careful estimate of all the associated uncertainties such as statistical and systematic errors was developed.

It appeared that any enantiomer-favouring photochemical effect at this wavelength is weak, since both a-alanine and DAP enantiomeric excesses were found to be small, at most of the order of 1% as shown in Table 7.3. Here, the e.e. = 1% falls within the error bars of the experiment and the detection technique. The original chromatograms are depicted in Fig. 7.6.

The small amount of material was the main limiting parameter in the precise determination of an enantiomeric excess. In the near future, higher amounts of material might be produced with a larger photon flux, possible with the new synchrotron radiation beamline DESIRS at SOLEIL, that just finished construction in France. Furthermore, in future experiments, the energy of the circularly polarized synchrotron radiation might be changed from X = 167 nm to other wavelengths, better corresponding to circular dichroism spectra of amino acids and their molecular precursors in the vacuum ultra violet region.

In light of these results, the hypothesis that circularly polarized light might be one source responsible for enantiomeric excesses of amino acids in some meteorites and, more generally, that circularly polarized light may be directly related to the origin of biomolecular homochirality on Earth remains untested.

Table 7.3 Enantiomeric excesses identified in the amino acids alanine and 2,3-diaminopropanoic acid after irradiation with circularly polarized light

Amino acid

Polarization of light

Corrected e.e. [%]

a-Alanine

unpolarized

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