ALMA observations of the IRDC Clump G34.43+00.24 MM3: complex organic and deuterated molecules

We have observed complex organic molecules (COMs) and deuterated species toward a hot core/corino (HC) associated with the infrared dark cloud clump G34.43+00.24 MM3 with the Atacama Large Millimeter/submillimeter Array. We have detected six normal-COMs (CH₃OH, CH₃CHO, CH₃CH₂CN, CH₃OCH₃, HCOOCH₃, and NH₂CHO), one deuterated-COM (CH₂DCN), and two deuterated fundamental molecules (D₂CO and DNC) toward G34.43+00.24 MM3 HC. None of these lines, except for CH₃OH, are detected toward the shocked regions in our data, which suggests that COMs do not originate in shocks. The abundance of the COMs relative to CH₃OH in G34.43+00.24 MM3 HC is found to be similar to those in high-mass hot cores, rather than those in hot corinos in low-mass star-forming regions. This result suggests that the physical conditions of the warm-up phase of G34.43+00.24 MM3 HC are similar to those of high-mass sources. On the other hand, the D₂CO abundance relative to CH₃OH in G34.43+00.24 MM3 HC is higher than that of other hot cores, and seems to be comparable to that of hot corinos. The relatively high D₂CO/CH₃OH ratio of G34.43+00.24 MM3 HC implies a long cold starless phase of G34.43+00.24 MM3 HC.