ABSTRACT
Spectroscopy is the characterization of matter through themeasure-
ment of its interaction with light. The discovery by Isaac Newton of
the sprawl of colors (dispersion) of sunlight by a prism has been
the foundation of further developments of spectroscopy. Joseph von
Fraunhofer used a diffraction grating for the same goal and observed
dark bands in the spectrum of the sunlight. Walter N. Hartley
contributed to make the link between the position of atoms in the
periodic table and the observed bands in spectra. The invention of
the spectroscopy has induced a fantastic advanced in knowledge
of universe due to its ability to determine the composition of the
sun and stars. It has been then possible to analyze not only remote
materials, but also the light sources, gas, and liquids in laboratories
since the end of the nineteenth century. The twentieth century
saw the development of new spectroscopic techniques and the
improvement of the sensitivity of the devices in order to detect
smaller and smaller concentrations of chemical components. The
basis of spectroscopy is given considering the distinction between
elastic and inelastic scattering, before investigating the way to
improve the sensitivity of devices by field enhancement.