| 摘要 |
A mass spectrometer is disclosed comprising a first chamber 10 and a second chamber 5 with an inter-chamber aperture 12 located therebetween. An ion guide 13 is located in the first chamber 10 and an ion mobility spectrometer or separator 6 is located in the second chamber 5. As ions are accelerated towards the ion mobility spectrometer 6 from a relatively low pressure region, they pass initially into the first chamber 10 provided with a first gas or mixture of gases, preferably helium, having a first average density or molecular weight M1. The ions are then transmitted by the ion guide 13 on into the second chamber 5 which is provided with a second gas or mixture of gases with a second average density or molecular weight M2, wherein M1 < M2 and preferably M2/M1 / 4. The helium gas provided in the first chamber 10 minimizes ion fragmentation and ion discrimination effects as ions are accelerated into a relatively high pressure region 5. |
