Physical detecting devices light

Light interacts with solid materials as scattering, absorption, transmission (transmittance), reflectance (both regular and diffuse), and diffraction. The purpose of spectroscopy is to quantify or qualify these interactions by the use of a variety of photon-produdng and photon-detection devices. The physics of these interaction phenomena and devices will be presented in this chapter. 

Up to now, a large part of the international scientific attention was devoted to the study of metallic nanoparticles (either single particles or in a colloid ensemble) (3, 14). Milling nanometric apertures in a metallic film is an intuitive way to manufacture new nanophotonics devices that are robust and highly reproducible. Although this concept appears very simple, such apertures exhibit attractive physical properties, such as localization of excitation light, strong isolation fi om emission produced by unbound species, and an increase in apparent absorption and emission yield. The simplicity of the structures and their ease of use should further expand their application towards the real-time detection and identification of a small number of molecules. 

In another detection method, an oil sorbent is used that changes in physical properties when it absorbs oil and thus triggers a device. An example of this would be a sorbent that loses it strength when oil is absorbed. The sorbent is placed in contact with a spring and a switch, which is activated when oil enters the sorbent. This type of device is not effective for fast response. Other detection units are triggered by the differential light reflection or absorption properties of oil. 

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