Patent ID: 6441613
Filing Date: 2002-08-27
Classification: G01R,H02G

Abstract:
A method of NMR (nuclear magnetic resonance) excitation of a sample having a magnetic moment comprising:applying a longitudinal magnetic field to the sample; inverting the magnetization of at least a portion of the sample, using an FM pulse having a duration, wherein the FM pulse has asymmetrical characteristics, wherein a resulting magnetization profile MZ of the sample has an asymmetric characteristic, comprising at least a narrow transition and a broad transition, and wherein the magnetization profile has the formula: Mz=sin&it;â€ƒ&it;h&it;â€ƒ&it;Ï€&it;â€ƒ&it;r&it;â€ƒ&it;sin&it;â€ƒ&it;h&it;â€ƒ&it;Ï€&it;â€ƒ&it;v+cos&it;â€ƒ&it;2&it;â€ƒ&it;Ï€&it;â€ƒ&it;qcos&it;â€ƒ&it;h&it;â€ƒ&it;Ï€&it;â€ƒ&it;r&it;â€ƒ&it;cos&it;â€ƒ&it;h&it;â€ƒ&it;Ï€&it;â€ƒ&it;vwhereinr=d-Ï‰0&it;â€ƒ&it;bv=(c+d)-Ï‰0&it;â€ƒ&it;(a+b)q=12&it;â€ƒ&it;Î©02-(c-Ï‰0&it;â€ƒ&it;a)2wherein a, b, c, d and &OHgr;0 are parameters having real values, &ohgr;0 is the Larmor frequency and wherein aâ‰ 0, and (câ‰ 0 or dâ‰ 0), wherein if q is imaginary, Mz=sin&it;â€ƒ&it;h&it;â€ƒ&it;Ï€&it;â€ƒ&it;r&it;â€ƒ&it;sin&it;â€ƒ&it;h&it;â€ƒ&it;Ï€&it;â€ƒ&it;v+cos&it;â€ƒ&it;h2&it;â€ƒ&it;Ï€&it;â€ƒ&it;&LeftBracketingBar;q&RightBracketingBar;cos&it;â€ƒ&it;h&it;â€ƒ&it;Ï€&it;â€ƒ&it;r&it;â€ƒ&it;cos&it;â€ƒ&it;h&it;â€ƒ&it;Ï€&it;â€ƒ&it;v