The permanent electric dipole moments of the (B)over-tilde(2)Sigma(+) and (X)over-tilde(2)Sigma(+) states of lanthanum imide, LaNH

The optical Stark effect has been measured for the (B) over tilde (2)Sigma(+) - (X) over tilde (2)Sigma(+), 3(0)(1), and 2(0)(1)(P’=3/2) bands of lanthanum imide, LaNH, prepared in a supersonic molecular beam. The permanent electric dipole moment, mu, for the (X) over tilde (2)Sigma(+) state was determined to be 2.53+/-0.06 D from measurements of the second-order Stark shifts in the (B) over tilde (2)Sigma(+)- (X) over tilde (2)Sigma(+), 3(0)(1) band. (nu(3) is the La-N stretching vibration, of symmetry sigma(+).) The dipole moment in the (B) over tilde (2)Sigma(+) state is too small to be determined from the Stark shifts in this band, but could be determined from the first-order Stark splittings in the P’=3/2 component of the (B) over tilde (2)Sigma(+), 2(1) bending fundamental (of upper state pi symmetry); it was found to be 0.3+/-0.2 D. A comparison is made with LaO and other isovalent molecules involving Group IIIA atoms. (C) 2003 American Institute of Physics.