Large amplitude motion of the acetylene molecule within acetylene–neon complexes hosted in helium droplets

Abstract

Superfluid helium droplets provide an ideal environment for spectroscopic studies with rotational resolution. Nevertheless, the molecular rotation is hindered because the embedded molecules are surrounded by a non-superfluid component. The present work explores the dynamical role of this component in the hindered rotation of C2H2 within the C2H2-Ne complex. A HENDI experiment was built and near-infrared spectroscopy of C2H2-Ne and C2H2 was performed in the spectral region overlapping the ν3/ν2 + ν4 + ν5 Fermi-type resonance of C2H2. The comparison between measured and simulated spectra helped to address the above issue.

Reaction dynamics within a cluster environment

“…As the slow rotations that have just been reviewed, the hindered rotations in molecular complexes are likely perturbed by the nonsuperfluid component of the complex. With collaborators, we have explored this issue both experimentally and theoretically by considering C 2 H 2 -Ne, Ar and Kr complexes, 187,188 . The (C 2 H 2 ) 2 dimer has been studied also.…”

Large amplitude motion within acetylene–rare gas complexes hosted in helium droplets

“…(d) Taken from Ref. 5 . fact with the angular basis vectors built from C 2 H 2 rotation lev-els of high j.…”

“…This issue was addressed in the Saclay laboratory for the C 2 H 2 −Ne complex in a work that associates HENDI spectroscopy with a theoretical modeling of the C 2 H 2 −Ne deformation dynamics. 5 Hereafter, this work is referred to as Paper I. It explored the deformation of the complex when the C 2 H 2 moiety is vibrationally excited in the vicinity of the ν 3 /ν 2 + ν 4 + ν 5…”

Dynamics of acetylene dimers hosted in helium droplets

“…The Ne-C 2 H 2 complex was explored first in a work which combines high resolution IR-HENDI-spectroscopy and numerical simulations. 10 The simulations are based on closecoupling calculations to derive the bound states of the Ne-C 2 H 2 complex. Then, the dynamical effect of the helium environment is modeled phenomenologically in the same spirit as recalled above for molecular rotations.…”

“…A side results in ref. 10 concerns spectra where acetylene only is present in the droplet. Close to lines assigned to the low energy component of the n 3 /n 2 + n 4 + n 5 Fermi dyad of the C 2 H 2 monomer, bands assigned to the K a (2 ' 1), K a (1 ' 0) and K a (0 ' 1) transitions of the dimer (C 2 H 2 ) 2 were observed.…”