摘要 : Coincidences between neutral particles and photoions have been measured at the C 1s edge of the CH_4 molecule. These neutral particles are either vacuum ultraviolet (VUV) photons or metastable fragments and their contributions can... 展开 Coincidences between neutral particles and photoions have been measured at the C 1s edge of the CH_4 molecule. These neutral particles are either vacuum ultraviolet (VUV) photons or metastable fragments and their contributions can be separated temporally. Observed VUV-photon-photoion coincidences were mostly triggered by Lyman emission in excited H atoms. Two metastable fragment-photoion channels were observed and assigned to H ~*-H~+ and H~*-CH_n ~+ (n=0-3) coincidences, where H~* signifies a metastable H atom. The coincidence yields as a function of photon energy revealed all the core excitations, but were particularly enhanced just above the C 1s ionization threshold and also displayed the vibrational structure related to the core-ionized C 1s-1 state. The metastable H atoms observed in the present study were produced in highly excited Rydberg states and could be partly field ionized. The approximate kinetic energy distributions of the metastable H~* atoms have been derived from the H ~*-H~+ coincidence measurements performed at the C 1s→3p and 3d resonances as well as just above the C 1s threshold. 收起