Synchrotron excitation-field ionization studies of high-Rydberg fragments produced after inner-shell ionization of small molecules

We have studied the production of neutral high-Rydberg (HR) fragments in small molecules after inner-shell excitation and ionization. Such fragments were ionized using a pulsed electric field and resulting ions were mass-analyzed with an ion time-of-flight (TOF) spectrometer. As an example, the results obtained at the C 1s ionization threshold of the methane molecule will be discussed.