  Introduction of a dielectric material in an NMR probe head modifies the
frequency response of the probe circuit, a phenomenon revealed by the detuning
of the probe. For NMR spectroscopy, this detuning is corrected for by tuning
and matching the probe head prior to the NMR measurement. The magnitude of the
probe detuning - the dielectric shift - provides direct access to the
dielectric properties of the sample, enabling NMR spectrometers to
simultaneously perform both dielectric and NMR spectroscopy. By measuring
sample permittivity as function of frequency, permittivity spectroscopy can be
performed using the new methodology. As a proof concept, this was evaluated on
methanol, ethanol, 1-propanol, 1-pentanol and 1-octanol using a commercial
CPMAS NMR probe head. The results accurately match literature data collected by
standard dielectric spectroscopy techniques. Subsequently, the method was also
applied to investigate the solvent-surface interactions of water confined in
the micropores of an MFI-type, hydrophilic zeolite with Si/Al ratio of 11.5. In
the micropores, water adsorbs to Br{\o}nsted acid sites and defect sites,
resulting in a drastically decreased dielectric permittivity of the
nano-confined water. A theoretical background for the new methodology is
provided using an effective electric circuit model of a CPMAS probe head with
solenoid coil, describing the detuning resulting from insertion of dielectric
samples in the probe head.
