Photoabsorption, photoionization, and neutral‐dissociation cross sections of SiF4, SiCl4, and Si(CH3)4 in the extreme‐ultraviolet range

The absolute photoabsorption cross sections (σt) and photoionization quantum yields (η) of SiF4, SiCl4, and Si(CH3)4 have been measured in the 50–100 nm range, from which we have evaluated the absolute photoionization cross sections (σi) and the total cross sections for nonionizing processes, i.e., the neutral‐dissociation cross sections (σd) following superexcitation. In addition to the broad structures in the σt curve for SiF4 around 95, 83, 78, 74.5, and 70 nm, oscillating structures which have not been found previously are revealed around 65 nm. These structures, which appear also in the present σi curve, are tentatively ascribed to the vibrational progressions of Rydberg states converging to the (4t2)−1C ionic state. Other oscillating structures in the 57–62 nm range are ascribed to the Rydberg states converging to the (5a1)−1D ionic state. Broad peaks around 95, 92, 75, and 58 nm are observed in the σt and σi curves of SiCl4. Rydberg structures converging to the 7a1−1 limit are observed in the σt ...