Orientation-dependent stopping power of a degenerate electron gas for slow homonuclear dimers

Abstract

We present a theoretical study on the orientation-dependent retarding force experienced by slow homonuclear dimers moving at arbitrary alignment with the direction of their flight in a three-dimensional degenerate electron gas of metallic densities. The analytical results are derived within the approximate framework of Brueckner for elastic scattering of an electron by a system of two auxiliary potentials of short range. The influence of the screened field of a single constituent of the slowly moving composite projectile on the scattering electron is modeled by an effective phase shift parameter η in the short-range potential in order to characterize the real-constituent system coupling due to displacement. The orientation-dependent closed expressions reveal the dependence of observables on the classical geometry and quantum dynamics. The interplay of wave-interference and multiple scattering in the orientation-dependent friction is analyzed for realistic sets of the input parameters. Comparison with experimental data is made and good agreement is found.

Orientation-dependent retarding force of a three-dimensional degenerate electron gas for slow homonuclear trimers

“…As in the previous work [6] for carbon dimers, we use a well-known [11,12] theoretical framework in order to get the complex scattering amplitude F k,k for elastic (|k| = |k | = k F ) electron scattering off the field of a slow linear homonuclear trimer. Considering the outgoing part of the scattered-electron wave function, we can write…”

“…The complex l functions encode the important modulating effects of multiple scattering. They are the solutions [6,12] of coupled algebraic equations…”

“…II, we are tempted to interpret the experimental [1] findings based on the theoretical results obtained [6] for carbon dimers. Since the aligned-dimer stopping power was almost perfectly equal to the stopping power of a single carbon atom, in nice harmony with the experiment, we may image a perfect shadow for the second atom behind the leading one.…”

“…However, already with a monatomic trimer one has to select possible molecular geometries for the penetrating objects which are reasonable [3][4][5] not only from the energetic but, equally importantly, from the allowed-space point of view as well. The aim of this theoretical study is to investigate the capability of a treatment for linear trimers, by extending a nonperturbative method applied [6] to interpret the data [1,[7][8][9] for C + 2 and H 2 + . That theory gave remarkable agreement with independent experimental findings with these intruders.…”

“…On the other hand, by treating the trimer stopping as a formal sum of two independent dimer stoppings, we would get R 3 = (2/3) and R 3,2 = 2 ratios. To understand, at least partially, the physics behind this perfect estimation we extend our method [6] to the case of linear-trimer intruders.…”