Mass Analysis in Time-of-Flight Analyser

The miz ratio of the ion is proportional to the square of the drift time. Hence, the mass of an ion can be determined by measuring its drift time once the analyser is 

Because not all the molecules get desorbed at the same time in exactly the same place, slightly different velocities are obtained for identical ions which can result in a broad peak and poor resolution. Using a reflector TOF set-up (Fig. 4.4) instead of the linear set-up shown above (Fig. 4.3), can overcome this problem. 

The linear tube allows detection of high molecular weights up to hundreds of kDa, but the resolution decreases as the mass increases. The reflector tube is limited to masses up to tens of kDa resolution, however, is improved. 

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