High-frequency electron paramagnetic resonance of metal-containing porphyrin compounds using a microcantilever

In this article, we report a novel technique of high-frequency electron paramagnetic resonance (HFEPR) using a microcantilever. In this method, a sample is mounted on a cantilever, and the field-gradient force associated with EPR absorption is detected as a cantilever bending. By using a micrometer-sized cantilever, this technique can be applied to a very tiny sample on the order of μg. In addition, the use of a piezoresistive cantilever makes the experimental setup easy and compact. In this study, we applied this technique to multi-frequency HFEPR measurements of metal-containing porphyrin compounds, which are an important composing element of metal-containing proteins and coenzymes such as hemoglobin and cyanocobalamin.