Chemical Processes in Rigid Media at Low Temperatures

Year: 1958

DOI: 10.7907/ZR35-PF54

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.

An apparatus has been developed for studying chemical processes in rigid inert media at low temperatures (4.2[degrees]K, 20[degrees]K., or 77[degrees]K. The materials to be studied are deposited as a thin film on a cold surface by vacuum effusion. Infrared and visible-ultraviolet absorption spectroscopy were used for detection.

The CS molecule and the benzyl radical were isolated in hydrocarbon films at 77[degrees]K. CF2 and NO3 were trapped in films of nitrogen at 20[degrees]K. Visible-ultraviolet spectra of these species were obtained.

The photolysis of diazomethane in films of nitrogen at 20[degrees]K has been extensively studied. By adding various reactants to the films, evidence for the following reactions has been obtained: [...].

Ozone in nitrogen films is decomposed by ultraviolet light and some nitrous oxide is produced. This is attributed to the reaction [...], which is a hot atom reaction.

Irradiation of mixtures of O3 and NO2 in nitrogen films yields NO3, N2O5, NO, and HNO3 (due to the presence of water). Irradiation of NO2 and O2 in nitrogen films yields O3 and NO.

The results obtained indicate that (1) hot atom or radical reactions occur in the film, and (2) photochemical fragments are energy-rich and may diffuse for a distance of at least a few molecular diameters in the rigid media.