H-atom Rydberg “tagging

Compared to the H-atom Rydberg tagging technique,65 the resolution of the present method is somewhat worse, by about a factor of two. This loss in resolution, however, is realized in general only for photodissociation studies. In a typical crossed beam experiment, the product translational energy resolution is usually limited by the energy spread of the initial collision energy rather than the detection scheme. On the other hand, the present... 

In this chapter, we will describe the most recent advances made in our laboratory on the unimolecular dissociation of the important H2O molecule as well as the bimolecular reactions, 0(1D) + H2 —> OH + H and H + HD — H2 + D, using the H-atom Rydberg tagging TOF technique. Through these studies, detailed dynamical information can be extracted experimentally for these important systems. 

Fig. 1. Detection schemes for H-atoms. Rydberg tagging technique is slightly different from the (1 + l )-REMPI detection scheme in which the H atom is directly ionized Rydberg tagging only pumps the H atom to a high Rydberg state.

Using the H-atom Rydberg tagging time-of-flight crossed molecular beam technique, Dr. Ren studied the reaction resonance and non-adiabatic effects at a full quantum resolved level in the F + H2 system. Through state-to-state resolved experiments, he provided the first conclusive evidence of reaction resonances in the F %,2) + H2 -> HF + H reaction. The dramatic difference between the dynamics for the F( P3/2) + H2(j = 0,1) reactions represents a textbook example of the role of reactant rotational level in resonance phenomena in this benchmark system. Dr. Ren has also carried out a very high-resolution experimental study on the dynamics of the isotope substituted reaction, F( P3/2) -I- HD -> HF -I- D, with spectroscopic accuracy (a few cm ). These findings provided a very clear physical picture for reaction resonances in this benchmark system, which has eluded us for more than 30 years. 

This thesis will be organized as follows The Chap. 2 describes the H atom Rydberg tagging time-of-flight crossed molecular beam apparatus and experimental methods in our laboratory the Chap. 3 shows the research of resonance phenomenon in the F -I- H2 reaction in the Chap. 4, the breakdown of the B-O approximation in the F - - H2 reaction is introduced. 

Fig. 2.5 The arrangement of the H atom Rydberg tagging laser system. Reprinted with permission from Ref. [26]. 2005, American Institute of Physics...

An interesting application of the high-resolution H atom Rydberg tagging method has been the study of the four-atom OH + H2 —> H2O + H reaction. 

---