Note that these parameters also affect the rotational transition
rates through their dependence on grain charge.
The DC discharge nozzle was employed in the study of radicals or transient interstellar species to measure low-J rotational transitions and to determine the dipole moments (138), (139).
Working from GBT data collected in 2004 and 2005, Hollis and coworkers identified interstellar acetamide (C[H.sub.3]C(=O)N[H.sub.2]) toward Sgr B2(N-LMH) by means of 7 A and E state rotational transitions (171).
The other group of chiral molecules belong to [C.sub.2] group, which consists of a [C.sub.2] operation, but I shall treat this group of molecules separately, because they give only one type of rotational transitions, due to the permanent dipole moment being aligned to the [C.sub.2] axis.
As already stressed, one of the most crucial points of the present study lies in the characteristic feature of [C.sub.1] chiral molecules that all the three a-, b-, and c-types of rotational transitions take place simultaneously.
Terahertz frequencies (0.1 to 30 THz) span the range of low-energy excitations in electronic materials, low-frequency vibrational modes of condensed phase media, and vibrational and rotational transitions
This includes the region that will affect molecular rotation, though the preferred frequency of 2,450 MHz chosen by some microwave instrumentation manufacturers falls below any of the rotational transitions
that will occur in molecules.
Earlier, we used vibrational Raman spectroscopy for the investigation of gaseous [D.sub.2] samples at 300 K , however, with only J = 0 and J = 1 states populated at low temperature, the purely rotational transitions
yield more information.