Differential Cross Sections for Cold, State-to-State Spin–Orbit Changing Collisions of NO(v = 10) with Neon

Abstract

Inelastic scattering processes have proven a powerful means of investigating molecular interactions, and much current effort is focused on the cold and ultracold regime where quantum phenomena are clearly manifested. Studies of collisions of the open shell nitric oxide (NO) molecule have been central in this effort since the pioneering work of Houston and co-workers in the early 1990s. State-to-state scattering of vibrationally excited molecules in the cold regime introduces challenges that test the suitability of current theoretical methods for ab initio determination of intermolecular potentials, and concomitant electronically nonadiabatic processes raise the bar further. Here we report measurements of differential cross sections for state-to-state spin–orbit changing collisions of NO (v = 10, Ω″ = 1.5, and j″ = 1.5) with neon from 2.3 to 3.5 cm–1 collision energy using our recently developed near-copropagating beam technique. The experimental results are compared with those obtained from quantum scattering calculations on a high-level set of coupled cluster potential energy surfaces and are shown to be in good agreement. The theoretical results suggest that distinct backscattering in the 2.3 cm–1 case arises from overlapping resonances.

Recent advances in quantum theory on ro-vibrationally inelastic scattering

“…Recent advances have been made in understanding collisions with molecules in highly excited vibrational states. [20][21][22][23] Additional insights are obtained from the scattering of molecules that are oriented or aligned, which provided valuable insights into stereodynamics. [24][25][26][27][28] The orientation and alignment of molecules can be realized by lasers or external fields, in addition to the internal state selection.…”

“…176,177 Finally, transitions between different spin-orbit states of open-shell molecules to non-reactive scattering is a well-known phenomenon and quantum mechanical treatments with coupling of the rotational and electronic orbital and spin angular momenta have been widely reported for atom-diatom collisions. 23,[45][46][47] Extensions of these treatments to tetratomic systems would be highly desired.…”

Cold collisions of hot molecules

“…2 and probe the ground spin-orbit state following collision with Ar and Ne. 60,61 These results were compared with QMCC calculations done with CCSD(T) and MRCI PESs. As shown above, QMCC scattering calculations have been quite successful in reproducing the essential features in the experimental results for these spin-orbit conserving processes using CCSD(T) PESs.…”

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

“…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.…”