NQR DETECTION USING A MEANDERLINE SURFACE COIL

14N pure NQR detection in a thin-layer sample using a meanderline, or zig-zag, surface coil is reported. The RF magnetic field of the meanderline drops off approximately as exp- πh b), where b is the conductor spacing and h is the distance from the plane of the coil, and therefore is ideally suited for NQR detection in thin, planar samples. A meanderline with 11 conducting strips of 4 cm spacing was used to observe the 14N ν-resonance line in sodium nitrite at sample distances up to 1.6 cm, where the RF field has dropped to less than 1 e. The meanderline results are compared with those obtained using a solenoid of comparable dimensions. It is also shown that the sensitivity of NQR detection using surface coils is greatly enhanced by using fast-pulsing techniques such as the strong off resonance comb, which can produce an order-of-magnitude or better improvement in the signal-to-noise ratio over more conventional (T1-limited) techniques. © 1991.