Photoionization threshold of CS2 in solid neon

The photoionization threshold of CS2 in solid neon was determined via photoionization of a CS2/Ne sample in situ at 5 K. The source of light for ionization was conducted from synchrotron radiation. The increase of fluorescent intensity of the cation CS2+ was measured by means of a laser-induced fluorescence scheme. A threshold energy 10.31 ± 0.02 eV was found for photoionization of CS2 in solid neon. Relative to the ionization energy in the gas phase this value corresponds to an additional barrier 0.24 eV due to the matrix cage. Hence the ejected electron needs 0.24 eV excess kinetic energy to escape the matrix cage.