Ring-Puckering Effects on Electron Momentum Distributions of Valence Orbitals of Oxetane

Abstract

The binding energy spectra and electron momentum distributions for the outer-valence molecular orbitals of oxetane have been measured utilizing (e, 2e) electron momentum spectrometer with non-coplanar asymmetric geometry at the impact energy of 2500 eV. The experimental momentum distributions were compared with the density functional theory calculations employing B3LYP hybrid functional with aug-cc-pVTZ basis set. It was found that the calculation at planar geometry (C2v) completely fails to interpret the large "turn-up" at low momentum region in electron momentum distribution of the highest occupied molecular orbital (HOMO) 3b1, while the calculations considering the thermal abundances of planar (C2v) and bent (Cs) conformers or the thermally populated vibrational states of ring-puckering motion have significantly improved the agreement. The results indicate that the ring-puckering motion of oxetane has a strong effect on the electron density distribution of HOMO.

Oxetanes and Oxetenes: Fused-Ring Derivatives

“…Electron momentum spectroscopy of oxetane was reported by Chen, leading to the binding energy spectra and the electron momentum distribution for the outer-valence molecular orbitals. 14,15 It was shown that the ring-puckering motion of oxetane has a dramatic influence on the electron density distribution of the highest occupied molecular orbital.…”

Electron Momentum Spectroscopy Study on the Valence Electronic Structure of Dimethyl Sulfide Considering Vibrational Effects

“…Distinct discrepancies between the experiments and calculations were observed, especially for the 5b 2 orbital, which is mainly the C–S σ bonding orbital. Numerous factors may lead to the discrepancies, for example the deviation from plane wave impulse approximation (PWIA) (distorted wave effect), − relativistic effect, − and vibrational effect. − …”

“…Therefore, the equilibrium geometry of the molecule is commonly invoked to calculate theoretical momentum profiles (TMPs) when interpreting EMS results. However, recent investigations − have shown that for polyatomic molecules, the nuclear vibrational motions have noticeable influence on EMPs. To fully estimate vibrational effects on EMPs theoretically, Watanabe et al proposed a harmonic analytical quantum mechanical (HAQM) approach, , in which all the vibrational modes were taken into account and the contributions of each mode can be estimated individually.…”

“…To fully estimate vibrational effects on EMPs theoretically, Watanabe et al proposed a harmonic analytical quantum mechanical (HAQM) approach, , in which all the vibrational modes were taken into account and the contributions of each mode can be estimated individually. It was demonstrated that not only the low-frequency vibrational modes − , but also the high-frequency ones ,, play important roles in interpreting the experimental EMPs. The influence of nuclear dynamics on EMPs can alternatively be analyzed using molecular dynamics simulations. − , In order to have a more detailed exploration on the nuclear dynamics effect, Morini et al investigated EMPs for a larger and structurally more flexible molecular target dimethyl ether ((CH 3 ) 2 O) .…”

Influence of molecular vibrations on the valence electron momentum distributions of adamantane

“…[25][26][27][28] Because of its unique ability to image individual electron orbitals in momentum space, EMS can provide a powerful means to investigate how molecular orbital patterns are affected by the vibrational motions of molecules. Indeed, recent EMS studies on various polyatomic molecules [29][30][31][32][33][34][35][36][37][38] have shown that electron momentum profiles may considerably be affected by molecular vibrations, and that EMS experiments in conjunction with recently developed theoretical approaches are capable of disentangling the interplay between the electronic and nuclear dynamics. 30,31,[34][35][36][37][38] It is therefore of interest to apply the EMS technique to the study of the nuclear dynamics effects for diamondoids.…”