Patent ID: 7391212

Claim:
A resonator apparatus for electron spin resonance (ESR) measurements, the resonator comprising: a dielectric ring resonator; a coupling element for exciting the dielectric ring resonator with radio frequency energy and for coupling ESR measurement signals out of the dielectric ring resonator; a sample vessel extending through said ring resonator, said sample vessel being configured as a single flexible tube; a liquid conveyor for conveying a liquid sample substance through said flexible tube while it extends through the ring resonator wherein the flexible tube extends from the liquid conveyor through the dielectric ring resonator with a substantially constant inner diameter; and an autosampler for directing distinct sample substances one after another through the liquid conveyor and the flexible tube and for cyclically conveying and stopping the distinct sample substances to produce a flow of the liquid sample substance consisting of a non-homogeneous composition that changes stepwise in a direction of the flow.