Hyperfine structure ofND3

Abstract

Pure inversion spectra for the ͉J,K͘ϭ͉1,1͘ level of 14 ND 3 and of 15 ND 3 are recorded at 10 kHz resolution using a molecular-beam microwave-UV double-resonance spectrometer. The observed spectra are fully assigned, and the energies of all ͉J,K͘ϭ͉1,1͘ hyperfine levels of both deuterated ammonia isotopomers are obtained. The shifting and splitting of the manifold of hyperfine levels in external electric fields is calculated and its implications for molecular-beam deceleration and trapping experiments are discussed.

Thermometry of Guided Molecular Beams from a Cryogenic Buffer‐Gas Cell

“…Several techniques for state detection of cold molecules have been used so far [34,35,36,37,38,39,40]. Among them, depletion methods, as adopted in previous experiments carried out by our group [35,40], are particularly advantageous since they are applicable to a large range of molecules and avoid the difficulties of the light-induced fluorescence (LIF) and resonance-enhanced multi-photon ionization (REMPI) detection techniques.…”

A Storage Ring for Neutral Molecules

“…The horizontal lines indicate the levels of the ν 2 umbrella vibration of ammonia where the two lowest levels correspond to ν 2 = 0 and ν 2 = 1 for the case of a single potential well (barrier is absent). Due to the finite barrier height, the levels are split into a symmetric level and an antisymmetric level and the energy difference between these two levels, the inversion splitting W inv , is 0.053 cm −1 for 14 ND 3 [63]. The inversion splitting for normal ammonia, 14 NH 3 , is 0.79 cm −1 [64].…”

“…The choice of 14 ND 3 over 14 NH 3 is made because the magnitude of the inversion splitting is significantly reduced upon deuteration. This leads to a 2 Deuterated ammonia, 14 ND 3 , is a boson [63] and the Pauli exclusion principle demands that the total wave function including the nuclear spin has to be symmetric if two deuterium atoms are interchanged. Levels with nuclear spin wave functions of E symmetry are denoted para-ammonia while levels with A 1 or A 2 symmetry are denoted ortho-ammonia [65].…”

“…Nevertheless, due to this coupling there are many hyperfine levels present. For instance, the |J, K = |1, 1 low-field seeking state of 14 ND 3 consists of 48 separate hyperfine components in an electric field [63].…”

State-selective detection of velocity-filtered ND3molecules

“…[2,3] Many methods have been developed over the past years to prepare neutral molecules in the millikelvin to microkelvin range. These methods have been applied in high-resolution spectroscopy [4,5] as well as collision studies. [6][7][8] Two main approaches are currently available for the production of cold neutral molecules (see [2] and references therein): 1.…”