Study of electrospray ion mobility dependence on the ion bunch drift velocity in the radio frequency quadrupole

The objective of this work is the study of the ion mobility dependence of electrospray Gramicidin S ions [M + 2H]2+ on the ion bunch drift velocity under variation of the specific electrical field strength at certain gas number density in the range from 0 to 300 Td. The ion mobility measurements were carried out under rotational excitation of ions using custom built gas filled segmented radio frequency quadrupole with the nitrogen buffer gas pressure of 1.9 Pa. The resulting ion mobility dependence of [M + 2H]2+ Gramicidin S ions upon the bunch drift velocity is essentially weaker, than it could be expected from the hard sphere collision model. By comparing the acquired ion mobility dependencies with the theoretical ones derived from the hard sphere collision model we suppose that the attractive polarization potential takes an essential part into the ion-molecular interaction even for such big organic ions as Gramicidin S.