Double swept band selective excitation

Abstract

The paper describes the design of band selective excitation and rotation pulses in high resolution NMR by method of double sweep. We first show the design of a pulse sequence that produces band selective excitation to the equator of Bloch sphere with phase linearly dispersed as frequency. We show how this linear dispersion can then be refocused by nesting free evolution between two adiabatic inversions (sweeps). We then show how this construction can be generalized to give a band selective $x$ rotation over desired frequency band. Experimental excitation profiles for the residual HDO signal in a sample of $99.5\%$ D$_2$O are obtained as a function of resonance offset.