Generalization of an Open Dynamically Harmonized Cell for Ultrahigh FT ICR Resolution.

FT ICR mass spectrometry is the leader in resolving power among all mass spectrometry methods. Introduction of the dynamically harmonized measuring cell─a closed-cylindrical cell with specifically shaped electrodes─helps to reach the resolving power of more than 10 7 with a magnetic field of about 7 T. From the theory of FT ICR mass spectrometry it follows that the resolving power of this type of instrument depends linearly on the magnetic field under various conditions. However, the results obtained on this type of mass spectrometer with the maximum magnetic field achievable today did not show a proportional increase in resolving power. In one of our previous papers, we assumed that the reason for this was insufficient vacuum inside the cell, since vacuum quality should be at least proportional to the magnetic field, since the mean free run time decreases proportionally to the magnetic field growth. We have presented an open modification of the dynamically harmonized cell that can help improve the cell pumping conditions. However, the electric potential distribution inside this new cell is slightly different from the ideal (harmonic) one, obtained inside the closed version of the cell, and the resolving power may have been limited by this difference.