Tuning probehead

In practice it is usually unnecessary to determine exact pulse widths for each sample we can use approximate values determined for each probe-head, except in certain 2D experiments in which the accuracy of pulse widths employed is critical for a successful outcome. Proper tuning of the probehead is advisable, since pulse widths will normally not vary beyond 10% with well-tuned probeheads. 

Figure 8.2.17 Photograph of a two-coil, multi-tuned probehead, with two solenoids arranged vertically. The impedance matching networks are shielded in copper boxes...

The most commonly used probehead is the inverse dual probehead, which contains an additional coaxial coil that is tuned to resonance frequency, surrounding the detection coil for hetero-... 

The experiments described in this article are usually performed under complete proton decoupling. Thus, in addition to the H coil and the standard lock signal, one needs two more frequencies to be delivered to the sample. The simplest approach would be a fixed probehead, with an additional coil double tuned to, for example, and The drawback of such a probehead is... 

Fig. 9 Photograph of two narrowbore probeheads. a aluminium jacket sealing the double helix used for thermo stating b high pressure vessel c platform carrying the autoclave d capacitors e capacitor platforms f tuning rods g high pressure connector h thermocouple i BNC connector j Pt-100 connector k copper tubing and 1 widebore adapter.

Figure 3.44. Tuning and matching an NMR probehead. The dark line represents the probe response seen for (a) a mis-tuned and (b) a correctly tuned probe head.

Figure 2. Photograph of two narrowbore probeheads a) aluminum jacket sealing the double helix used for thermostating, b) high pressure vessel, e) platform carrying the autoclave, d) capacitors, c) capacitor platforms, f) tuning rods, g) high pressure connector, h) thermocouple, i) BNC connector, j) Pt-100 connector, k) copper tubing, I) widebore adapter.

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