The resonant transfer of energy from the inversion sublevels in NH 3 to He atoms in triplet Rydberg states with principal quantum number n = 38 has been controlled using electric fields below 15 V/cm in intrabeam collisions at translational temperatures of ∼1 K. The experiments were performed in pulsed supersonic beams of NH 3 seeded in He at a ratio of 1:19. The He atoms were prepared in the metastable 1s2s 3 S 1 level in a pulsed electric discharge in the trailing part of the beams. The velocity slip between the heavy NH 3 and the lighter metastable He was exploited to perform collision studies at center-of-mass collision speeds of ∼70 m/s. Resonant energy transfer in the atom–molecule collisions was identified by Rydberg-state-selective electric-field ionization. The experimental data have been compared to a theoretical model of the resonant dipole–dipole interactions between the collision partners based on the impact parameter method.
We report on the Stark deceleration and electrostatic trapping of
14NH $(a^{1}\ensuremath{\Delta})$ radicals. In the trap, the molecules are excited on the spin-forbidden $A^{3}\ensuremath{\Pi}\ensuremath{\leftarrow}a^{1}\ensuremath{\Delta}$ transition and detected via their subsequent fluorescence to the $X{^{3}\ensuremath{\Sigma}}^{\ensuremath{-}}$ ground state. The
1∕e trapping time is $1.4\ifmmode\pm\else\textpm\fi{}0.1\text{ }\text{s}$, from which a lower limit of 2.7 s for the radiative lifetime of the $a^{1}\ensuremath{\Delta}$,
v=0,
J=2 state is deduced. The spectral profile of the molecules in the trapping field is measured to probe their spatial distribution. Electrostatic trapping of metastable NH followed by optical pumping of the trapped molecules to the electronic ground state is an important step toward accumulation of these radicals in a magnetic trap.
We report on the production of a pulsed molecular beam of metastable NH (
a1Δ) radicals and present first results on the Stark deceleration of the NH (
a1Δ,J=2,MΩ=−4) radicals from 550 m/s to 330 m/s. The decelerated molecules are excited on the spin-forbidden
A3Π←a1Δ transition, and detected via their subsequent spontaneous fluorescence to the
X3Σ−,v"=0 ground-state. These experiments demonstrate the feasibility of our recently proposed scheme [Phys. Rev. A 64 (2001) 041401] to accumulate ground-state NH radicals in a magnetic trap.