Supersonic Molecular Beam Optical Stark Spectroscopy of MnH.

The large moment of inertia, large magnetic moment, and possible large permanent electric dipole moment of manganese monohydride, MnH, makes it a prime candidate for ultra-cold molecule production via Stark deceleration and magnetic trapping\footnote {J.R. Bochinski, E.R. Hudson, H.J. Lewandowski, and J. Ye, \textit{Phys. Rev. A} \textbf{70}, 043410 (2004).}'\footnote {S.Y.T. van de Meerakker, R.T. Jongma, H.L. Bethlem, and G. Meijer, \textit{Phys. Rev. A} \textbf{64}, 041401(R) (2001).}. Here we report the first molecular beam production of MnH and the analysis of the Stark effect in the (0,0) $A^{7} \Pi $ -- $X^ {7}\Sigma ^{+}$ band. The sample was prepared by laser ablation of solid Mn in an H$_ {2}$ supersonic expansion. The low rotational temperature ($<$50 K) and near natural linewidth resolution ($\sim$50 MHz) facilitated analysis of the $^{55}$Mn (I=5/2) and $^{1}$H (I=1/2) hyperfine structure. A comparison of the derived field-free parameters with those obtained from sub- Doppler optical\footnote{T.D. Varberg, J.A. Gray, R.W. Field, and A.J. Merer, \textit{J. Mol. Spec.} \textbf{156}, 296-318 (1992).} and Doppler limited infrared\footnote{I.E. Gordon, D.R.T. Appadoo, A. Shayesteh, K.A. Walker, and P.F. Bernath, \textit{J. Mol. Spec}., \textbf{229}, 145-149 (2005).} measurements will be made. Progress on the analysis of the Stark effect will be given.