Nascent internal energy distributions of MgH produced in the reaction of Mg(3s3p 1P1) with a variety of polyatomic molecules

Nascent rotational quantum state distributions of MgH(v=0,1) produced in the reactions of excited Mg(3s3p 1P1) with a variety of polyatomic molecules have been determined using the laser pump-and-probe technique. The distributions are generally bimodal, with one component peaked at low rotational energy and another component at high values of the rotational quantum number N. Except for (CH3)2O, and (C2H5)2O, which produced very little rotationally excited MgH, all compounds with C–H, N–H, and or O–H bonds showed microscopic branching ratios for the ‘‘high-N’’ component of 0.5±0.1. For the reactants SiH4, GeH4, and PH3, the high-N branching ratio was ≥0.9. The results are interpreted in terms of competition between side-on, insertive, and end-on, abstractive attack of the reagent bonds. Little vibrational energy was found in MgH product for any molecule, consistent with extremely ‘‘late’’ energy release for these heavy–light–heavy kinematic conditions. The results are compared to those from similar studies of the reactions of O(3P), O(1D), and F(2P).