Effect of Reagent Rotational Excitation on Dynamics of F+H₂→HF+H

The dynamics of the F+H₂(v=0,j=0, 1) reactions have been studied at the collision energy of 1.27 kcal/mol using a high-resolution crossed molecular beam apparatus. HF product rotational state resolved differential cross sections have been obtained at the v′=1, 2, 3 levels. The product HF(v′=2) angular distributions are predominantly backward scattered for both H₂ (j=0, 1) reagents. However, the distributions of product HF(v′=2) rotational states for theF+H₂(v=0,j=0) reaction are signi cantly di erent from those for the F+H₂(v=0,j=1) reaction. Experimental results show that the rotational excitation of H₂ produces rotationally ‘hotter’ HF(v′=2) product. In addition, the HF(v′=3) product is more likely scattered into the forward direction when the H₂ reagent is populated at j=0 state, which could be attributed to a slow-down mechanism.