Dimensional parameters of metal-containing structures such as films, interconnects, wires and stripes, and nanoparticles are detected using an approach involving plasmon-excitation and one or more metal-constituency characteristics of the metal-containing structures. According to an example embodiment of the present invention, plasmon-exciting light is used to excite plasmons in a structure, the plasmon excitation being responsive to the metal constituency. A characteristic of light reflected from the structure is then used to detect dimensional parameters of the structure. In one implementation, a characteristic of the reflected light that is related to the state of plasmon excitation in the structure is used to detect the dimensional parameters. In another implementation, the angle of incidence of the plasmon-exciting light is used in connection with an intensity-related characteristic of light reflected from structure to detect one or more dimensions of the structure. In still another implementation, the intensity of different wavelengths of the reflected light is used to determine one or more dimensions of the structure. With these approaches, the dimensions of a variety of structures such as metal films, interconnects, wires, and stripes are determined.