The ultraviolet absorption coefficients have been, determined for CO2, CO, O2, H2O, N2O, NH3, NO, SO2, and CH4 in the wavelength region between 1850 and 4000 A. By using a double‐beam instrument and a 10‐cm path length, we achieved sensitivities of 10−4 cm−1 most of the time, permitting a considerable extension of the literature data.

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An extension of the research on carbon dioxide described in Part I was conducted at pressures from one atmosphere to fifty atmospheres, and on liquid carbon dioxide at 10°C, near the critical temperature. Also a novel method was developed in using the direct impact of the fission fragments on the gases (uranium-235 in contact with the gases on bombardment with thermal neutrons). The action of inhibitors other than nitrogen dioxide to stop the back reaction of the decomposed carbon dioxide was also investigated. Since the decomposition of nitrous oxide by ionizing radiation was determined as a dosimeter, parallel decomposition experiments were conducted with the nitrous oxide and carbon dioxide under identical conditions. The G values of the carbon dioxide decomposition were determined with and without inhibitors at high pressures and the liquid state by pile radiation and by the impact of fission fragments. The G values ranged from 0.005 to 8.5±0.5 depending upon conditions. The basic mechanism described in Part I was confirmed. No difference in behavior was noticed in the gas phase when irradiated with pile radiation or fission fragments. In the liquid state, it could be shown that the ``hot spots'' or ``hot needles'' along the ionization track of the fission fragments are not ``hot'' enough to initiate the thermal decomposition, which in the case of nitrous oxide requires a heat of activation of 53 kcal and for carbon dioxide 128 kcal. However, two markedly different behaviors between the gaseous and liquid states were noted. First, the inhibitors became inefficient in the liquid carbon dioxide phase, and second, the G value for the decomposition of liquid carbon dioxide was found to be 4 to 5. These behaviors are not altered if the liquid carbon dioxide is irradiated with normal pile radiation or with fission fragments.