A novel NMR detector of the present invention comprises a radio frequency (RF) resonance circuit. The RF resonance circuit includes a principal detector element and a sample chamber. The principal detector element defines an inductor of the electronic resonance circuit. In one embodiment of the invention the sample chamber containing the inductor is a stainless steel sample chamber. The stainless steel sample chamber is a modified toroid cavity detector (TCD). The inductor is formed by an atomically flat metallic disk, such as, a mercury pool, with a predefined surface area, such as a surface area of 7.5 cm2. Liquid mercury is incorporated into a toroid cavity detector as the inductor of the resonance circuit, and as the base of the cavity. Self-assembled molecular structures (monolayers and multilayers) are formed using long-chain alkane thiols, which are known to chemically react with silver, gold, platinum, palladium, and mercury surfaces.