| 摘要 |
Ions generated under an atmospheric pressure pass through vacuum chambers partitioned through first, second and third fine holes. The ions are led to an MS part where the ions are mass-analyzed. A first vacuum chamber adjacent to an atmospheric pressure part has not vacuum pump for independently pumping this chamber. The first vacuum chamber is evacuated by a common pump together with a second vacuum chamber via a bypass hole formed in the wall having the second aperture. A pressure of the first vacuum chamber can be set to several 100 Pa, while a pressure of the second vacuum chamber can be set to several 10 Pa. Sufficient desolvation has been attained by an ion acceleration voltage of approximately 100 V in the first vacuum chamber, while a speed spread can be restrained. The ions are accelerated by approximately 10 V in the second vacuum chamber, an the speed spread can be restrained as low as possible.
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