Fig. 3
From: Water-mediated NOE: a promising tool for interrogating interfacial clay–xenobiotic interactions
A schematic illustrating the radio frequency (r.f.) pulse sequence used for a homonuclear one-dimensional WaterLOGSY experiment. A 180° Gaussian shape pulse (Φ 2), in combination with a gradient (g 1), is used to select for the water signal. During the mixing time (t mix), the NOE from the water is transferred to a molecule only if they are in contact with each other. A small continuous gradient is applied during t mix to reduce the effect of radiation damping. Lastly, both water flipback [5-ms sinc-shaped 90° pulse (Φ 5)] and excitation sculpting (Φ 6 and Φ 8) are used for water suppression before signal acquisition. (Note The pulse length for excitation sculpting was calibrated to achieve optimal water suppression) The phase cycling for each pulse is as followed: Φ 1 = 0, Φ 2 = 0123, Φ 3 = (0)4 (2)4, Φ 4 = 0, Φ 5 = 02, Φ 6 = (2)8(3)8(2)8(3)8(0)8(1)8(0)8(1)8, Φ 7 = (0)8(1)8(0)8(1)8(2)8(3)8(2)8(3)8, Φ 8 = (2)4(3)4(2)4(3)4(0)4(1)4(0)4(1)4, Φ 9 = (0)4(1)4(0)4(1)4(2)4(3)4(2)4(3)4, and Φ rec = 0123012323012301. The gradient amplitudes (%) were set to 40, 31, and 11 for g 1, g 2, and g 3, respectively. The phase cycle requires at least two transients