  This paper presents a systematic survey of the deuterated and 13C
isotopologues of a variety of oxygen-bearing complex organic molecules on Solar
System scales toward the protostar IRAS 16293-2422B. We use the data from an
unbiased molecular line survey between 329 and 363 GHz from the Atacama Large
Millimeter/submillimeter Array (ALMA). The observations probe scales of 60 AU
where most of the organic molecules have sublimated off dust grains and are
present in the gas-phase. The complex organic molecules can be divided into two
groups with one group, the simpler species, showing a D/H ratio of
approximately 2% and the other, the more complex species, D/H ratios of 4-8%.
This division may reflect the formation time of each species in the ices before
or during warm-up/infall of material through the protostellar envelope. No
significant differences are seen in the deuteration of different functional
groups for individual species, possibly a result of the short time-scale for
infall through the innermost warm regions where exchange reactions between
different species may be taking place. The species show differences in
excitation temperatures between 125 K and 300 K. This likely reflects the
binding energies/sublimation temperatures of the individual species, in good
agreement to what has previously been found for high-mass sources. For dimethyl
ether, the 12C/13C ratio is found to be lower by up to a factor of 2 compared
to typical ISM values similar to what has previously been inferred for
glycolaldehyde. The results point to the importance of ice surface chemistry
for the formation of these complex organic molecules at different stages in the
evolution of embedded protostars and demonstrate the use of accurate isotope
measurements for understanding the history of individual species.
