Hydrogen Chemistry: Perspective on Experiment and Theory

Abstract

In view of the rapidly accelerating pace of research in atmospheric kinetics, it is increasingly difficult to review a subject as large as the relevant ‘hydrogen’ chemistry. This subject may be discussed broadly in terms of the principal mechanisms which are thought to operate in planetary atmospheres, particularly in the terrestrial stratosphere and mesosphere. But such a discussion would necessarily be both superficial and repetitive. Alternately, one may be tempted to do a quick review of the vast store of kinetic information on the many reactions of H, OH, HO₂, H₂O₂, HCl, HNO₃, etc., in order to bring such information up to date. This is a laudable objective, but a note of caution must be sounded. Although it was very important that reviews of that type were first undertaken 10 to 15 yr ago (Kaufman, 1964) when experimental work on elementary reactions was barely getting under way, the situation is very different today, and the reviewing task is either a full-time occupation or an arduous labor of love. It is therefore particularly important that the users of reaction rate information, i.e. aeronomic modelers, not be confronted with too many alternate and often contradictory sources, because such alternate sources of input data cloud the comparison of modeling calculations. Modelers must therefore be encouraged to use the best, most up-to-date sources such as the Leeds evaluations (Baulch et al., 1972) the NSRDS-NBS monographs (e.g., Johnston, 1968), the most recent NBS evaluations (e.g., Garvin and Hampson, 1974), review papers in the Journal of Physical Chemical Reference Data and in the International Journal of Chemical Kinetics such as those on OH (Wilson, 1972) and HO₂ reactions (Lloyd, 1974) and on stratospheric reactions (Hampson, 1973). The CODATA-3 Bulletin (Garvin, 1971) and the ‘review of reviews’ paper by Gevantman and Garvin (1973) are particularly valuable guides to and through the reviews thicket.