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In recent years, isolated starless cores have been revealed to have significant
chemical differentiation with very low abundances of carbon-bearing molecules
(such as CO and its isotopologues) in their cold, dense interiors. The inner
regions of such cores, however, may be quite interesting, e.g., if contraction
or collapse begins there. To explore these regions, we present detections of
six isolated starless cores in the 1_11-1_10 line of H2D+ at 372 GHz using the
new HARP instrument at the James Clerk Maxwell Telescope. Since the detection
of this line requires very dry conditions on Mauna Kea (i.e., tau_225 < 0.05),
only a multi-beam receiver system like the 4 x 4 HARP array can locate H2D+
emission across such cores in a practical amount of observing time. In all
cases, the brightest line emission is coincident with the local peak of sub-
millimetre continuum emission, but significant H2D+ emission is detected offset
from the continuum peak in some. In addition, we describe the thermal and
turbulent velocity fields in these cores revealed by these lines.
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