Molecular Beam Optical Stark Spectroscopy Of Magnesium Deuteride

Abstract

Light polar, paramagnetic molecules, such as magnesium hydride, MgH, are attractive for slowing and trapping experiments because these molecules have both non-zero permanent electric dipole, $\mu$$_{el}$, and magnetic dipole, $\mu$$_{m}$ moments. The permanent electric dipole moment is particularly relevant to Stark deceleration which depends on the ratio of the Stark shift to molecular mass. Here we report on the Stark effect in the (0,0) A$^{2}$$\Pi$ – X $^{2}$$\Sigma$$^{+}$ band system of a cold molecular beam sample of magnesium deuteride, MgD. The lines associated with the lowest rotational levels are detected for the first time. The field-free spectrum was analyzed to produce an improved set of fine structure parameters for the A$^{2}$$\Pi$(v = 0) state. The observed electric field induced splittings and shifts were analyzed to produce permanent electric dipole moments, $\mu$$_{el}$,of 2.561(10)D and 1.34(8)D for A$^{2}$$\Pi$(v = 0) and X$^{2}$$\Sigma$$^{+}$(v=0)states, respectively. This is the first molecular beam study of MgD.