Reaction dynamics of Mg(3s4s 1S0) with H2: interference of the MgH product contribution from the lower Mg(3s3p 1P1) state

The nascent MgH product distribution obtained in the reaction of Mg(3s4s 1S0) with H2 was found to be identical to that from the Mg(3s3p 1P1) state. The 4 1S0 population is found to be much larger by a factor >18 times than that relaxed to the 3 1P1 state within the pump–probe delay time. The possibility of a secondary production from the 3 1P1 state appears to be negligible in the subsequent measurements of the H2 pressure and the delay time dependences of the MgH rotational lines. These consequences confirm that the MgH product is caused mainly by the direct Mg(4 1S0)–H2 collision, rather than a secondary product from the 3 1P1 state.