The photochemistry of tert-butyl nitrite, (CH3)3CONO, adsorbed on Ag(111) at 355 nm has been studied using time-of-flight and reflection adsorption infrared spectroscopy (RAIRS) for coverages ranging from 0.1 to 50 ML. For all coverages a thermal and hyperthermal NO desorption distribution is observed due to photodissociation. The thermal component originates from hyperthermal NO molecules from the first and second layer, which were trapped by the silver substrate. The cross section for photodissociation is independent of coverage and matches the gas phase value. This is consistent with a direct excitation into the S1 state. For coverages exceeding 5 ML the outermost layers still dissociate, but RAIRS shows that in the more inward layers caging is preventing dissociation. Due to caging only isomerization of tert-butyl nitrite is allowed, as is evident from the RAIRS.

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An UHV apparatus has been designed and constructed for studying the interaction between adsorbates and photons. Since a variety of light sources and experimental geometries are used in these studies, the system was designed to be as flexible as possible. The system is put on a single frame so that it can be transported from one photon source to another. A compact, exchangeable, high-pressure cell is designed to provide easy access for photons to the crystal. To allow the study of small poly-atomics the following combination of detection techniques are installed: thermal desorption spectroscopy (TDS), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), low-energy electron diffraction (LEED) and reflection - adsorption infrared spectroscopy (RAIRS). Furthermore, a sample exchange system in combination with liquid nitrogen sample cooling is incorporated. The exchange system allows three samples to be stored in the main chamber. The sample exchange capability does not restrict the cooling capabilities - 85 K within an hour after turning on the liquid nitrogen flow and 85 K within minutes after flashing to 800 K.