2004A&A...427..887F

We have studied the ortho, para, and, in the case of D₃⁺, meta forms of the multiply-deuterated isotopes of H₃⁺, under physical conditions believed to be appropriate to pre-protostellar cores. As deuterons have integral nuclear spin, I=1, Bose-Einstein statistical laws apply. Having extended the network of chemical reactions used in our previous study (Walmsley et al., 2004A&A...418.1035W), we have calculated the population densities of ortho- and para-D₂H⁺ and of ortho- and meta-D₃⁺. In the former case, comparison is made with the recent observations of para-D₂H⁺ in the prestellar core 16293E (Vastel et al., 2004ApJ...606L.127V). Using radiative transition probabilities computed by Ramanlal & Tennyson (2003A&A...406..383R), we have predicted the intensities of the near infrared vibrational transitions of the deuterated isotopes of H₃⁺. Many of these transitions can be observed, in absorption, only from above the Earth's atmosphere, but some might be detectable through atmospheric windows.