Stretching-mode specificity in the Cl + CH 3 D( v 1 -I, v 1 -II, and v 4 = 1; | jK 〉) reactions: dependency on the initial | jK 〉 selectivity.

The title reactions were studied at a collisional energy of 5.4 kcal mol -1 in a crossed-beam product-imaging experiment. The dynamics attributes of the dominant ground-state CH 2 D(0 0 ) and the accompanied C-D bend-excited CH 2 D(6 1 ) products were imaged in reactions with totally 16 ro-vibrationally selected states of the CH 3 D( v i , | jK 〉) reagents. We found that all three vibrational excitations yielded marked | jK 〉-dependent rate-enhancements in forming the (0 0 , 0/1) s product pairs. Furthermore, for a given rotational | jK 〉-mode, a vibrational-mode propensity of v 4 > v 1 -I > v 1 -II in rate promotion and a clear manifestation of the Fermi-phase-induced interference effect of the latter two were observed. Compared to the reactivity of the rotationless state | jK 〉 = |00〉, a minute rotational-excitation of all three stretch-excited CH 3 D( v i = 1) reagents could yield significantly higher reaction rates for the product pair (0 0 , 0) s , but not so for (0 0 , 1) s . The signals in forming the (6 1 , 0) s pair were clearly notable but smaller than that of the ground-state reaction product pair, (0 0 , 0) g . An opposite propensity of v 1 -II ≈ v 1 -I > v 4 with a milder dependency on the initial | jK 〉-states was observed. The angular distributions of the (0 0 , 0) s pairs were nearly identical for all ro-vibrationally excited reagents, displaying the typical trait for a direct abstraction of the rebound mechanism. Similar distributions were found for the (6 1 , 0) s pairs; yet, both pairs deviated substantially from the peripheral feature of the ground-state reaction pair of (0 0 , 0) g . Those of the (0 0 , 1) s pairs in reactions with v 4 -excitation featured a prominent forward-peaking distribution-suggestive of a time-delayed, resonance-mediated pathway, again with little dependency on the initial | jK 〉-states. As for the reactions with the two Fermi-dyads, v 1 -I and v 1 -II, albeit showing globally similar distributions to that for v 4 , a substantial variation with the initial rotational-mode excitation could be discerned in the forward-peaking features. To unravel the impact of the Fermi-phase on the | jK 〉-dependent attributes, we adopted a comparative approach by contrasting the observations in reactions with the Fermi-dyad reagents (the superposition states) to those with the pure-state reagents. Remarkable distinctions are unveiled and elucidated with the unexplained results explicitly pointed out, which call for future theoretical investigations for deeper understanding.