Chapter 4:Broadband Fast Field-cycling Relaxometer: Requirements, Instrumentation and Verification

The technical requirements of a broadband fast field-cycling (FFC) NMR relaxometer are discussed. Specifically, the instrumentation of an optimized home-built FFC relaxometer, located in Darmstadt (Germany), is presented in detail. Magnet design, power electronics and various probe heads for a temperature range from 10 to 1400 K are described. The special feature of this relaxometer is the combination of several individually controlled magnetic systems for different field ranges and tasks, which allows for fast field-switching and low-field applications down to 1H Larmor frequencies of about 3 Hz. Possible error sources in the construction and adjustment of an FFC relaxometer and their influences on relaxation measurements are discussed and verification methods for its proper operation are proposed and validated.