2+1 resonance-enhanced multiphoton ionisation spectra of the (B) over tilde E-1 "-(X) over tilde (1)A(1) 2(0)(n) (n greater than or equal to 6) transitions of NH3(ND3) have been recorded, and the room temperature spectra rotationally analysed. The variation with nu (2) of the spectroscopic parameters is discussed. An increased rate of predissociation is observed for the 2(0)(11) and 2(0)(12) bands of NH3. This is attributed to anon-adriabatic interaction with a nearby state of A(2)" most probably the (D) over tilde'(1)A(2)" (4sa(1)') Rydberg stare enhancing the rate of the known (B) over tilde E-1 " --> (A) over tilde (1)A(2)"