The ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages
  (ASHES). V. Deuterated Molecules in the 70 $\mu$m dark IRDC G14.492-00.139
  We have observed the 70 $\mu$m dark infrared dark cloud (IRDC) G14.492-00.139
in the N$_2$D$^+$ $J$=3--2, DCO$^+$ $J$=3--2, DCN $J$=3--2, and C$^{18}$O
$J$=2--1 lines, using the Atacama Large Millimeter/submillimeter Array (ALMA)
as part of the ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages
(ASHES). We find that the spatial distribution is different among the observed
emission from the deuterated molecular lines. The N$_2$D$^+$ emission traces
relatively quiescent regions, while both the DCO$^+$ and DCN emission emanates
mainly from regions with signs of active star-formation. In addition, the
DCO$^+$/N$_2$D$^+$ ratio is found to be lower in several dense cores than in
starless cores embedded in low-mass star-forming regions. By comparing the
observational results with chemical model calculations, we discuss the origin
of the low DCO$^+$/N$_2$D$^+$ ratio in this IRDC clump. The low
DCO$^+$/N$_2$D$^+$ ratio can be explained if the temperature of the dense cores
is in the range between the sublimation temperature of N$_2$ ($\sim$20 K) and
CO ($\sim$25 K). The results suggest that the dense cores in G14.492-00.139 are
warmer and denser than the dense cores in low-mass star-forming regions.
