A schematic diagram of the experimental setup is shown in Figure l. Using a rubber band, the balloon was attached to metal tubing that to the inlet tube of the mass spectrometer. The balloon was inflated with helium gas, and then deflated three times by using a rotary vacuum pump (Edward,E2M5) to degas its inner surface. After the final inflation of the balloon with helium the vacuum line was evacuated using a rotary and a turbo molecular pump (Blazers TPH 602)the vacuum of the system was observed to be 1.2x10-3 torr using a Pirani gauge (Alcatel P1 2)
The partial pressures of the gases in the balloon were determined from the mole fractions and the total pressure measured in the balloon the total pressure in the balloon was measured using a capacitance gauge (MKS,626A),and the mole fraction of the gases in the balloon was deter mined using a mass spectrometer (Finigan Mat,271/45).The peak sensitivities of the mass spectrum were determined by comparison with primary standard reference gases.
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