Correlation Study of the Spin–Orbit State-Resolved Scattering of Al(²P) in Oxidation Reaction and Nonreactive Collision

Abstract

Spin−orbit coupling plays an important role in chemical reactivity, especially in reactions that require the change of electron spin states. However, it is difficult to measure and analyze the reaction dynamics between spin−orbit splitting states, particularly for splitting states with a small energy difference. In this study, we find that nonreactive scattering of spin−orbit splitting states can provide complementary information that is overlooked in chemical reaction studies. Here, the oxidation reactivities of spin−orbit Al( 2 P 1/2,3/2 ) states with small energy difference of 112 cm −1 are clearly distinguished in the high rotational AlO(v = 0 and 1, N) products at low collision energy of 507 cm −1 using a laser ablation crossed-beam and time-sliced ion velocity mapping technique, in conjunction with state-selected nonreactive scattering studies. For both the AlO(v = 0 and 1) channels, the spin−orbit relative reactivity σ 3/2 /σ 1/2 increases with the increase of rotational level N of AlO products. However, for AlO(v = 0), the reactivity of the Al( 2 P 3/2 ) excited state is consistently lower than that of the Al( 2 P 1/2 ) ground state, whereas for AlO(v = 1), the reactivity of Al( 2 P 3/2 ) is higher than that of Al( 2 P 1/2 ) at a higher rotational state. The relative reactivity of spin−orbit split Al( 2 P) states at different scattering angles shows a more pronounced enhancement of forward scattering relative to side and backward scattering for Al( 2 P 3/2 ) when a higher rotationally excited AlO is produced. Nonreactive scattering studies of Al( 2 P) suggest that the Al( 2 P 3/2 ) state is deexcited to the ground Al( 2 P 1/2 ) state at the sideways and backward scattering directions, and the deexcitation is supposed to reduce the reactivity of the excited Al( 2 P 3/2 ) at the corresponding direction.

Imaging Rovibrational Excitation of Scattered YO Molecules in Inelastic Collisions with Kr and Ne

“…The energy transfer between YO­(X 2 Σ + , v , N ) and Ne/Kr was studied in laser-ablation crossed molecular beam apparatus combined with a time-sliced ion VMI setup, which has been described in detail. ,− Here is a brief description. The YO beam was generated by ablating a Y metal rod (97% Y, Alfa) with yttrium-containing oxides on the surface under a laser at the wavelength of 532 nm (1–3 mJ/pulse).…”

“…Energy transfer between atoms and molecules is an essential process in collisions, which can lead to various outcomes that are important in chemical reactions and physical processes in energy conversion, such as vibrational excitation, rotational excitation, or electronic excitation. − With the advances of molecular beam, laser state-selective ionization, and velocity map imaging (VMI) techniques, the collisional differential cross sections (DCSs) can be obtained and the scattering mechanisms are revealed both in the classical and quantum pictures. ,,− The hard-sphere model and attractive-repulsive model have provided a general understanding of the scattering trajectory. Forward scattering is due to the long-range attraction at large impact parameters, and small-impact-parameter scattering leads to sideways and backward distribution.…”