The optoacoustic method has by now an almost one-centurY-long history of appl ication in spectroscopy, but it was only with the advent of the laser that it became a convenient and effective method among the vast family of spectroscopy techniques. The great variety of these techniques is capable of tackling most diversified tasks, such as the achievement of a high sensitiv ity and a high spectral or temporal resolution. The optoacoustic method is one of the simplest and most versatile ways to attain a high sensitivity for both gaseous and condensed media. It is precisely for this reason that...