1996, ApJ, 461, 897-901
This paper discusses a search for interstellar CH3D via its J(K)=1(0)-0(0) line at 232 GHz and J(K)=2(0)-1(0) and J(K)=2(1)-1(1) transitions at 465 GHz toward the star-forming region Orion-KL. Two of the lines were seen, but the third was only marginally seen. The data indicate that the Orion hot core methane fractional abundance is f < 6e-4, consistent with chemical models. The paper also presents laboratory measurements of all three lines.
1992, ApJ, 393, 188-192
Interstellar N2 abundances toward 13 dark clouds and warm star-forming regions are derived from column densities measured for N2H+. The relatively high N2 concentrations suggest that most of the nitrogen in dense clouds is in the form of molecular nitrogen and that condensation onto grains may not play a large role in the nitrogen chemistry of dense gas.
N2H+ is an excellent tracer of quiescent material
In contrast with HCO+, N2H+ spectra exclusively exhibit the quiescent extended ridge gas toward Orion-KL. Toward KL, the N2H+ spectrum exhibits two narrow velocity components which suggest that two clouds may be present in the region. N2H+ appears to be an excellent tracer of ambient, quiescent gas. The velocity structure observed in this molecule toward KL may be related to the star formation observed in the Orion region.