THE MOBILITIES OF IONS AND CLUSTER IONS DRIFTING IN POLAR GASES

The mobility of ions drifting in polar gases is explored both theoreti cally and experimentally. New experimental results are presented for ( i) NO+ ions drifting in H2O (the reduced zero-field mobility K-0((0)) is 0.66+/-0.07 cm(2)V(-1)s(-1)), (ii) H3O+(H2O)(3) ions drifting in H2 O (K-0((0))=0.43+/-0.06 cm(2)V(-1)s(-1)), and (iii) NO+(CH3COCH3)(n) i ons (n=2,3) drifting in CH3COCH3 (K-0((0))=0.041+/-0.010 cm(2)V(-1)s(- 1) for n=2 and K-0((0))=0.050+/-0.015 cm(2)V(-1)s(-1) for n=3). A numb er of theoretical models for ion mobilities in polar gases are describ ed. The models are compared with the available experimental data and a reasonable agreement is obtained. For larger cluster ions the measure d mobilities are considerably smaller than the calculated values. Some possible reasons for the discrepancies are discussed, including momen tum transfer outside the capture cross section, dipole-dipole interact ions, ligand exchange, inelastic collisions, and the validity of Blanc 's law. (C) 1997 American Institute of Physics.