| 摘要 |
PROBLEM TO BE SOLVED: To measure a very small moisture amount, for example, of 1wt.ppm or lower, in a gas of a compound containing fluorine and carbon, for example, C5F8 gas for production of a semiconductor, to guarantee specifications as to the moisture amount. SOLUTION: A lithium ion is attached to the sample gas, for example, C5F8 gas, to ionize the sample gas. C5F8 gas is a neutral molecule but since it is polarized to some extent, the lithium ion attaches to it. Lithium ion is also attached to moisture contained in the sample gas. The C5F8 will not dissociate, because cohesive energy of the lithium ion is low, and fluorine ions "19" near to mass 18 of water are thus not generated. The very trace amount of moisture in the sample gas is thereby measured accurately, by mass-analyzing the sample gas irradiated with the lithium ions. COPYRIGHT: (C)2005,JPO&NCIPI
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