| In order to investigate the dynamics and the resonance phenomenon of the F(2P) reactions with H2(j=0,1) in the lower collision energy region, we have developed a new experimental apparatus using the crossed molecular beam technique and the high resolution time-of-flight Rydberg tagging method. There are two new features in this apparatus: a rotating source design such that collision energy can be varied for crossed beam studies of chemical reactions and two rotating detectors for collecting signals at two laboratory angles simultaneously.We have carried out crossed molecular beams scattering studies with full quantum state resolution for F(2P) reactions with H2(j=0,1) in the collision energy range of 0.19～1.20 kcal/mol using the highly sensitive H atom Rydberg tagging time-of-flight method. With the help of theoretical calculations, reactive mechanisms were analyzed.Pronounced forward scattered HF products in the v'=2 vibrational state were clearly observed for the F(2P3/2) +H2(j=0)→HF(v',j')+H reaction at the collision energy of 0.52 kcal/mol, which was attributed to both the ground and the first excited Feshbach resonances trapped in the peculiar HF(v'=3)--H'vibrationally adiabatic potential, with significant enhancement due to constructive interference between the two resonances, by full quantum dynamical calculations, carried out using an accurate, full potential energy surface constructed for this study, using high level ab initio methods with small empirical corrections.In addition, effect of single quantum H2-rotation on dynamical resonances in F+H2→HF + H reaction was also investigated. No contribution to the HF(v'=2) product from the two resonances ((003) and (103)) was observed for the H2(j=1) reaction at the collision energy of 0.52 kcal/mol and 0.56 kcal/mol, the H2(j=1) reactions proceed predominantly via the continuum tunneling reaction mechanism, which is a direct reaction processes. There are three components to the HF(v'=2) product: the ground resonance, the excited resonance and the continuum tunneling mechanism for the H2(j=0) reaction at the collision energy of 0.56 kcal/mol, and the contribution of the ground resonance is predominantly forward scattered; The excited resonance component shows a forward-backward scattered peaks, and the forward one is slightly stronger than the backward one; while the continuum tunneling mechanism produces a clear backward scattered distribution. The H2(j=0) reaction at the collision energy of 0.19 kcal/mol proceeds mainly via the continuum tunneling reaction mechanism. While the pronounced forward HF(v'=2) product scattering peak at the H2(j=1) reaction is due to the two Feshbach resonances, (003) and (103).
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