Dynamical (e,2e) studies of tetrahydropyran and 1,4-dioxane

Abstract

We present experimental and theoretical results for the electron-impact ionization of the highest occupied molecular orbitals of tetrahydropyran and 1,4-dioxane. Using an (e,2e) technique in asymmetric coplanar kinematics, angular distributions of the slow ejected electron, with an energy of 20 eV, are measured when incident electrons at 250 eV ionize the target and scatter through an angle of either -10° or -15°. The data are compared with calculations performed at the molecular 3-body distorted wave level. Fair agreement between the theoretical model and the experimental measurements was observed. The similar structures for these targets provide key insights for assessing the limitations of the theoretical calculations. This study in turn facilitates an improved understanding of the dynamics in the ionization process.

Triply differential (e,2e) studies of phenol

“…Note that the M3DW approach has been demonstrated to be quite successful in reproducing collision cross section data for the low and intermediateenergy electron impact ionisation of atoms and molecules. 19 The present work extends our previous results for molecules of some biological interest, such as pyrimidine, 20 tetrahydrofuryl alcohol (THFA), 21,22 tetrahydrofuran (THF), 22, 23 1,4-dioxane, 23,24 and tetrahydropyran (THP). 24 The structure of the present paper is as follows.…”

“…For θ a = −5 • , we observe excellent agreement in terms of the shape between the distorted wave calculations and the experimental measurement. This result is somewhat surprising in that previously the distorted wave calculations have failed to reproduce the experimental width of the binary feature of other molecular targets [20][21][22][23][24] under this same kinematical condition. However, when we consider the binary regions for the other kinematical conditions of θ a = −10 • or −15 • , we see substantial differences between the experimental data and the distorted wave calculations.…”

“…A detailed description of the employed method can be found elsewhere. [20][21][22][23][24] Briefly, however, a wellcollimated beam of electrons with energy E 0 = 250 eV collide with gaseous phenol at low pressure, with some electrons ionising the phenol target to yield two-outgoing electrons. The present high-purity sample of phenol was sourced from Ajax Unilab (assay > 99%), and is a solid at room temperature.…”

“…The relative intensity of the TDCS in the binary and recoil regions therefore contain signatures relating to the dynamics of the ionisation process. [20][21][22][23][24]…”

Sulphur hexaflouride: low energy (e,2e) experiments and molecular three-body distorted wave theory

“…However we think that it is still of interest to see how good or bad it is since it is very difficult (for us) to get access to enough computer time to perform the proper averages so it would be useful to know if there are cases where it can be used. So far, we have found that it is not good for some intermediate sized molecules [6], [18][19][20], but suprisingly a reasonably good approximation for the big molecules we have examined [21][22][23][24][25].…”