Zero-range-potential model for strong-field molecular processes: Dynamic polarizability and photodetachment cross section

Abstract

We develop a general theoretical framework for the analytical description of the interaction of a model diatomic molecular system with an intense, arbitrarily polarized monochromatic laser field. The model molecule comprises an electron in the field of two zero-range potentials separated by the internuclear distance. This model has an exact analytical solution within the theoretical framework of the quasistationary quasienergy (Floquet) approach. In addition to the development of this general framework, we also present a detailed analysis of the weak-field limit, within which we obtain both the frequency-dependent polarizability and the angle-resolved photodetachment cross section for the model system. These fundamental properties are analyzed for both homonuclear and heteronuclear molecular systems in a linearly polarized laser field, for both ground and excited electronic states, and for arbitrary orientation of the molecular axis relative to the polarization vector of the laser field. The analytical expressions for the polarizability and angle-resolved photoelectron spectra exhibit characteristic double-slit interference patterns, allowing one to study their dependence on the parameters of the problem beyond the level of the Born approximation.

Интерференция При Туннельной Ионизации Электрона, Связанного Двумя Короткодействующими Потенциалами

“…44304.16452 Метод потенциалов нулевого радиуса широко используется в атом-ной и ядерной физике, а также в физике конденсированных сред [1-3]. Важными приложениями метода стали описание нелинейной ионизации, генерации высоких гармоник в сильных лазерных полях [4][5][6][7] и простая модель туннельного эффекта в атомной микроскопии [8]. Известно аналитическое решение задачи о поляризации и туннельном отрыве электрона из короткодействующего потенциала атомарного отрицатель-ного иона.…”

Photodetachment of a model molecular system by an elliptically polarized field

“…In order to specify the dynamical parameters A p and A R introduced in our phenomenological analysis above, we use a model of a one-electron molecular system comprised of an electron in the field of two attractive ZRPs separated by the distance R (or the vector R). Since details of this model have been discussed recently in [48], here we briefly discuss only its main ingredients. Each isolated zero-range (or δ-function) potential supports a single bound s state,…”

“…an electron in the field of two δ-centers localized at positions r = R 1 = R/2 and r = R 2 = −R/2 has two bound states with energies E ± : the ground state, ψ + (r), and the excited state, ψ − (r). The corresponding wave functions can be represented as a superposition of two single-ZRP orbitals [48,51]:…”

“…a source of a secondary wave. This secondary wave and the initially emitted spherical wave interfere and exhibit interference fringes [9,48]. These two mechanisms leading to interference fringes cannot be distinguished in numerical simulations, but they are treated explicitly in the two zero-range potential (ZRP) molecular model [48,49].…”

“…In Section 3 we present our results for the simplest dynamical model of a molecule, i.e. one in which the potentials of the two atomic centers are described by (generally, non-equivalent) zero-range (or δ-function) potentials [48]. In Section 3.1 we describe this molecular model system briefly, and present explicit expressions for the dynamical parameters appearing in our general parametrization in Section 2.…”