Patent ID: 7449683

Claim:
An ion mobility method for separation, characterization, or identification of ions, comprising the steps: introducing said ions into an analytical gap filled with a gas; establishing a periodic time-dependent electric field of intensity E over said analytical gap, said periodic time-dependent electric field cancels contributions to time-averaged ion motion of a number, n (where n≧2), of leading terms in a series expansion for ion mobility, K, as a function of E/N (where N is number density of said gas), via a polynomial in powers of E/N: K ( E/N )= K (0)[1+ a ( E/N ) 2 +b ( E/N ) 4 +c ( E/N ) 6 +d ( E/N ) 8 +. . . a j ( E/N ) 2j ]; thereby achieving separation, characterization, or identification of said ions based substantially on coefficients with the (n+1) th and subsequent terms of said series expansion: a j where j=n−1.