Multidimensional steric effect for the XeF* (B, C) formation in the oriented Xe* (³P₂, M_J= 2) + oriented NF₃reaction

Abstract

Steric effect for the XeF* (B, C) formations in the oriented Xe* ((3)P(2), M(J) = 2) + oriented NF(3) reaction has been observed as a function of the mutual configuration between the molecular orientation and the atomic orientation in the collision frame. Molecular steric opacity function has been determined as a function of the atomic orbital alignment (L(Z)') in the collision frame. The larger reactivity at the side with the smaller reactivity at the molecular axis direction is observed for the XeF* (B, C) channels at each atomic orbital alignment. A good correlation between the shape of the molecular steric opacity function and the molecular geometry of NF(3) is recognized. The L(Z)' selectivity in the molecular steric opacity function is different between the XeF* (B, C) channels; in the sideways direction, the XeF* (B) channel is favorable at L(Z)' = 0, while the XeF* (C) channel is favorable at |L(Z)'| = 1. In contrast, at the molecular axis direction, the XeF* (B) channel is favorable at |L(Z)'| = 1, while the XeF* (C) channel is favorable at L(Z)' = 0. We propose the collision-induced harpoon mechanism for the XeF* (B, C) formation in the Xe* ((3)P(2)) + NF(3) reaction.

Collision-Induced Harpooning Observed in the Excimer Formation in the Oriented NF3 + Oriented Kr*(3P2, MJ = 2) Reaction

“…In order to accentuate the steric effects, we define the orientation term ( O (Θ)) and the alignment term ( A (Θ)) by , A ( Θ ) = italicI ( normalΘ , normalF 3 -end ) + italicI ( normalΘ , N-end ) 2 · italicI ( normalΘ , random ) − 1 O ( Θ ) = italicI ( normalΘ , normalF 3 -end ) − italicI ( normalΘ , N-end ) 2 · italicI ( normalΘ , random ) Here, I (Θ, N-end), I (Θ, F 3 -end), I (Θ, random) is the emission intensity at the N-end (Φ ∥ ), F 3 -end (Φ ∥ a ), and random (Φ off ) configurations, respectively. The orientation ( O (Θ)) and alignment ( A (Θ)) terms are shown in Figure as a function of the atomic orientation configuration (Θ).…”

“…In contrast with the NF 3 + Kr*( 3 P 2 ) system, the NF 3 + Xe*( 3 P 2 ) system has no reactivity at the molecular axis direction regardless of the atomic orbital alignment M L ′ . This difference can be explained by the difference in the interaction potential between two reaction systems; a theoretical calculation on the V 0 term for the NF 3 + Xe*( 3 P 2 ) system reveals that the NF 3 + Xe*( 3 P 2 ) system has the larger V 0 (repulsive) term as compared with that of the NF 3 + Kr*( 3 P 2 ) system from the longer intermolecular distance.…”

“…The experimental apparatus is similar to the one in our previous study. , In brief, the Kr*( 3 P 2 , M J = 2) atomic state was selected by using a 35 cm long magnetic hexapole, and the oriented NF 3 was prepared by using a 40 cm long electrostatic hexapole. In the present study, the oriented Kr*( 3 P 2 , M J = 2) atomic beam is oriented to the homogeneous magnetic orientation field B , and the oriented NF 3 molecular beam is oriented to the homogeneous electric orientation field E .…”

“…The NF 3 molecular beam is the same as the one used in our recent study for the XeF* formation in the NF 3 + Xe*( 3 P 2 ) reaction; the velocity distribution of the NF 3 molecular beam is characterized by the stream velocity of v s = 400 ms −1 and the translational temperature of T trans = 200 K. The orientational distribution W (cos γ E ) of the molecular axis with respect to the electric orientation field direction ( E ) was determined by the trajectory simulation for the state selection in the hexapole field. Here, γ E is the orientation angle of the NF 3 molecular axis with respect to E .…”

“…Most recently, we studied the multidimensional steric effects for the XeF*(B, C) formations in the oriented Xe*( 3 P 2 , M J = 2) + oriented NF 3 reaction that has the small quenching cross section (σ Q NF 3 = 23 Å 2 ); it belongs to group 2. In contrast with the other molecules belonging to group 1, the largest reactivity is observed at the sideways direction with poor reactivity at the molecular axis direction.…”