Sorption and desorption of gas in a hot-cathode ionization gauge

An omegatron has been used to analyse continuously the gases present during sorption/desorption experiments with a hot-cathode ionization guage. It is shown that the most abundant residual gas at the termination of ion sorption pumping is carbon monoxide. Ten per cent or less of the total gas originally sorbed is readily recovered at an exponential rate, indicating that this fraction of the gas is held at solid surfaces rather than within the solids themselves. It is also found that the fraction of gas that is readily recovered diminishes with successive pumping and recovery according to the relation ( i + ) 2 max is proportional to 1/ t , where t is the time recorded from initial operation of the experimental gauge and ( i + ) max is the positive ion current corresponding to the maximum pressure attained during recovery.