Efficient transfer of population between rotational levels in deuterated ammonia using THz transitions

This is the authors' abstract. We don't add key points for this paper.

We demonstrate the efficient transfer of population between rotational levels of ND3 using a commercially available table-top THz source. We use a Stark decelerator to prepare a packet of para-ND3 molecules in the 11− upper inversion component of the rotational ground state, and induce the 21+←11− electric dipole allowed transition both in the presence of an electric field and under field free conditions. Using THz chirps to address all hyperfine components, transfer efficiencies up to 87% are reached, limited by the power of the THz source. Population transfer from the 11− to the 21− level is demonstrated either by driving directly the 21−←11− transition in a field, or by a 11−→11+→21− double-resonance excitation scheme. In addition, we present a novel method to produce packets of ND3 (11−) with pure MJ=0 or |MJ|=1 character using the Stark decelerator, and a method to probe the MJ composition of a packet of molecules using THz excitation.