| 摘要 |
An ion guide comprises at least two sets of parallel elongate rods disposed circumferentially about a common axis, and to each set is applied independently a RF potential generating a multipole electric field and a DC potential. The order of the multipole field applied decreases from the highest order applied to the set of rods at the entrance end to the lowest order applied to the set of rods at the exit end. The order of each set can equal the number of rods and there can be a third set of rods. The sets can operate as dodecapole, hexapole, octapole or quadrapole ion guides. There can be a series of parallel rod segments about a common axis (fig 3) supplied with an RF potential to form a multipole field confining ions radially and a DC potential forming a field gradient to manipulate the ions axially, the order of multipole field decreasing progressively from a higher order at the entrance to a lower order at the exit to radially compress the ion beam. The hybrid ion guide can operate in a continuous mode using RF voltages to generate mulitpole fields and DC gradients along the axis (cooling mode) or by superimposing periodic pulses for trapping and releasing ions regions of different field-order (bunching mode). The device can be used as a collision cell in either mode or can be coupled to orthogonal TOF mass analyzers to enhance duty cycle. |
