Metastable H atoms from O 1s excitation/ionisation of HO

Harries, J.; Kuniwake, Miki*; Gejo, Tatsuo*; Homma, Kenji*; Sullivan, J. P.*; Azuma, Yoshiro*

We report here on studies where metastable H atoms are directly detected following the O 1s inner-shell excitation of the water molecule, revealing new information not accessible with the ion or photon techniques. Metastable H yield differs to partial/total ion yields and H fluorescence yield most strikingly near threshold, where a large peak is observed due to the capture of a Rydberg electron or slow photoelectron by a dissociation H ion, analogous to a similar observation for N production from N. The nature of the process is investigated by comparing the kinetic energies of H and H fragments, and also by detecting H in coincidence with H, OH, and O ions.