Laser Measurements of Trace Gases in the Atmosphere and in the Laboratory

Summary

A survey of laser investigations in the atmosphere is given, and more recent results of air pollution measurements by the differential absorption method are discussed in detail. In a second part single-atom detection in the laboratory is reviewed, and as an example an experiment is presented in which collision processes of single atoms were studied.

In the past decade the detection of small concentrations of atoms and molecules in the atmosphere and in the laboratory has been improved tremendously by the application of lasers. Due to the small divergence of the laser beam these methods are applicable over large distances so that for example the continuous monitoring of the ozone layer from ground-based stations became feasable. Using the high spectral density of laser light single-atom detection has been demonstrated in the laboratory. This is an important progress and implies many applications as e.g. in isotopic dating or for the production of extremely pure materials. Essential for both fields is the wavelength tunability of lasers since all optical detection methods rely on the absorption and emission of specific wavelengths by atoms and molecules.