The Unique Features

The measurement depth in the range 0 to 5 mm can be selected by simply exchanging the RF inserts. An insert-specific preset parameter table (optimal pulse length, operating frequency, etc.) is loaded in the minispec software, and no other set-up actions are required. The instrument is ready to perform experiments.

All parts of the probe are designed for maximal mechanical robustness and system stability. The RF inserts are robust from the electrical point of view as well. This robust design is a prerequisite for successful use of the mq-ProFiler in an industrial or production environment.

An important feature of the mq-ProFiler probe is the virtual absence of acoustic ringing and 1H background signal, allowing operation with an effective dead time of less than 15 µs. Anyone familiar with NMR at low magnetic fields or NMR of low-g nuclei even at high fields has probably struggled with acoustic ringing. The suppression of ringing and the absence of a 1H background signal allow the mq-ProFiler to detect signals from samples with short transverse relaxation times, e.g., paper. Other possible applications in polymer research and quality control involve the monitoring of cross-linking progress or the combination of mechanical stretch experiments with NMR relaxation measurements.

The mq-ProFiler is essentially immune to sample-induced effects on the tuning and matching conditions for the RF probe (a well-known problem in NMR). Frequent probe tuning is a routine operation for trained researchers in laboratory conditions. However, such manipulations are undesirable and troublesome when the analysis is carried out in production or in an uncomfortable environment with limited access time. This is actually the case for on-line quality control (QC) applications as well as for the in-situ measurements carried out during the Eureka E!2214 Project.

Fortunately, the special design of the resonant circuit in the mq-ProFiler RF probe makes it insensitive to the sample`s dielectric properties (Fig. 1), so that tuning and matching do not require readjustment after loading of the probe with the sample. Additionally, an insensitivity to the electromagnetic environment is achieved. Figure 1 shows the tuning curve for the mq-ProFiler before (top) and after (bottom) loading of the RF probe with a sample. No significant effects due to sample dielectricity are observed.