Excited states in the VUV photoionization process of liquid tetramethylsilane and alkanes

Some characteristic energies are observed in the first derivative of the photoionization spectrum of tetramethylsilane (TMS) cyclohexane and 2,2,dimethylbutane (DMB). They could correspond to "auto-ionizing" states situated above the ionization threshold. Some of these energies are assigned to Rydberg series converging to a vertical ionization potential in gas phase and persisting in liquid phase.