| 摘要 |
PROBLEM TO BE SOLVED: To develop a method and an apparatus for generating an unstable gas such as HNO<SB>3</SB>, HCl, H<SB>2</SB>O<SB>2</SB>, formaldehyde or the like as a stable standard gas in a low concentration for a long time. SOLUTION: The method of preparing a standard gas uses a diffusion tube method in which a gas is generated in the air from a solution dissolving the gas at a high concentration by the gas-liquid equilibrium (Henry's law). When the gas is generated in the air through a gas permeable membrane from the solution dissolving the gas in a high concentration by the diffusion scrubber method, and as the air, a clean air is used from which trace gas impurities are removed by absorption with an absorbing solution in which the gas through the gas permeable membrane by the diffusion scrubber method is not dissolved. COPYRIGHT: (C)2004,JPO
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