Production and deceleration of a pulsed beam of metastable NH (α1Δ) radicals

We report on the production of a pulsed molecular beam of metastable NH (a(1)Delta) radicals and present first results on the Stark deceleration of the NH (a(1)Delta, J = 2, M Omega = - 4) radicals from 550 m s(-1) to 330 m s-1. The decelerated molecules are excited on the spin-forbidden A(3)Pi <- a(1)Delta transition, and detected via their subsequent spontaneous fluorescence to the X-3 Sigma(-), v = 0 ground state. These experiments demonstrate the feasibility of our recently proposed scheme (2001 Phys. Rev. A 64 041401) to accumulate ground-state NH radicals in a magnetic trap. In addition, we propose to transfer the NH radicals from the a(1)Delta state to the X-3 Sigma(-) state using a cw-laser to allow cooling of the beam during trap loading.