Molecular beam studies of the F+D2 and F+HD reactions

Abstract

The F+D2 and F+HD reactions were investigated in a high resolution crossed molecular beams experiment at several collision energies. The DF product from both reactions was predominantly backward scattered although some forward scattered DF(v=4) was observed at the highest energy studied. The HF angular distributions from F+HD were quite different, showing considerable forward scattered (v=3) and no other identifiable structure. These results disagree with classical trajectory studies, which predict only small variations in the product angular distributions among F+H2 and its isotopic variants. They agree, however, with the predicted dependence of dynamical resonance effects on isotopic substitution. The results therefore support the conclusions drawn in the previous paper regarding the role of dynamical resonances in the F+H2 reaction.

Probing Quantum Dynamics of Elementary Chemical Reactions via Accurate Potential Energy Surfaces

“…A clear forward scattering peak was observed for the HF(v = 3) product, which was regarded as the signature of resonances. In addition, forward scattering for the DF(v = 4) product from F + D 2 as well as the HF(v = 3) product from F + HD were detected [53]. Later full quantum dynamics calculations of the F + H 2 reaction [54] on the SW potential energy surface [55] show that the observed HF(v = 3) forward scattering is not necessarily related to a reaction resonance.…”

Сверхбыстрая Динамика Химических Реакций

“…2. Контурные карты распределения скоростей образования (изофлаксы) для фто ристого дейтерия, появляющегося в работе [26] реакции F + D 2 FD + D. Резуль таты экспериментов с молекулярными пучками соответствуют двум различным энер гиям столкновений реагентов. При меньшей энергии столкновения (7,9·10 -2 эВ; а) продукт реакции DF рассеивается в основном назад; при повышении энергии столкно вения (14,3·10 -2 эВ; б) появляются продукты, рассеянные также вперед и имеющие колебательную энергию, соответствующую возбуждению уровня = 4.…”

“…. ., t 5 -это результаты теорети ческих расчетов формы волнового пакета [26] пучок стабильных отрицательных ионов С1НС1~ подвергался облучению, вызывавшему фотоотрыв электрона и образование С1НС1. Спектр энергий фотоэлектронов отражает колебательную структуру и позволяет полу чить оценку нижней границы времени жизни короткоживущего проме жуточного соединения С1НС1.…”

On the maximum in the differential cross sections of the F + H2 reaction in the region of small scattering angles

“…Of the most recent works, one can mention, e.g., the papers [4][5][6] (F + H 2 ), [7] (F + D 2 ), [8] (F + HD), and the reviews [9,10]. A pioneer role in examining the F + H 2 (D 2 , HD) reactions was played by the exper imental works of Lee's group [11][12][13][14][15][16][17]. In particular, the paper [13] reported the vibrationally (but not rotation ally) resolved differential cross sections of the HF product scattering from the F + H 2 (v = 0; j = 0, 1, 2) reaction obtained in crossed molecular beams at colli sion energies E col = 1.84, 2.74, and 3.42 kcal/mol (79.8, 119, and 148 meV).…”

“…In particular, the paper [13] reported the vibrationally (but not rotation ally) resolved differential cross sections of the HF product scattering from the F + H 2 (v = 0; j = 0, 1, 2) reaction obtained in crossed molecular beams at colli sion energies E col = 1.84, 2.74, and 3.42 kcal/mol (79.8, 119, and 148 meV). The paper [14] presented the anal ogous differential cross sections of the DF product from the F + D 2 (v = 0) reaction at E col = 0.79, 1.82, and 3.32 kcal/mol (34.3, 78.9, and 144 meV). The most important observation of the works [13,14] is a maximum in the angular distributions of the HF(DF) products from the F + H 2 (D 2 ) reactions with the high est accessible vibrational quantum number v', i.e., of HF(v' = 3) and DF(v' = 4), at small scattering angles θ ≤ 20° (in the center of mass frame).…”