“…Contributions could be present due to metastable S, SO or 02 fragments and, as discussed later, all of these species are in fact present. The metastable detector is able to detect those metastable species with excitation energies greater than the work function of the channeltron (estimated to be about 8 eV by Brunt et al [7]). Consequently, only O(3s 5S°) metastable atoms at 9.14 eV are detected, whereas O(2p41D), O(2p41S), S(3p41D), S(3p41S), and S(4s 5S°) metastable atoms do not produce any signal.…”