Field ionization of high-Rydberg fragments produced after inner-shell photoexcitation and photoionization of the methane molecule
We have studied the production of neutral high-Rydberg (HR) fragments from the CH4 molecule at the C 1s -> 3p excitation and at the C 1s ionization threshold. Neutral fragments in HR states were ionized using a pulsed electric field and the resulting ions were mass-analyzed using an ion time-of-flight spectrometer. The atomic fragments C(HR) and H(HR) dominated the spectra, but molecular fragments