Laser Photodissociation and Spectroscopy of Mass-separated Biomolecular Ions by Nicolas C. Polfer & Philippe Dugourd

Author:Nicolas C. Polfer & Philippe Dugourd
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

(3.21)

If we introduce the dimensionless parameters

(3.22)

and make a change of variables, we get the canonical form of the Mathieu equation

(3.23)

There are certain values of a x and q x for which the motion is stable in the xz plane; i.e., the x value does not exceed r 0, thus forming a region of stability. A similar argument applies to ay and q y . As can be seen from the definitions of a u and q u , they depend on the form of the confinement potential, the mass of the ion of interest, and the quadrupole geometry. Thus, for a particular trap size and ion type, one can realize the proper voltages to be applied for a stable operation.

The first region of stability, shown in Fig. 3.6, where 0 < q < 0.908 is particularly important because it contains the area with largest overlap of x-stable and y-stable regions. Consequently, this region is used in virtually all quadrupole mass filters. The advantage of representing the stability diagram in terms of these dimensionless parameters is that these a u and q u boundary conditions apply to every ion, independent of the ion’s m/z, the trap dimensions, and the voltages that are applied.

Fig. 3.6The first region of stability for a 2D linear quadrupole ion trap

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.