# Screening and enhancement of oscillating electric field in molecules

## TL;DR

This paper investigates how oscillating electric fields interact with molecules, revealing that molecular ro-vibrational states can significantly weaken or enhance the field inside molecules, with potential applications in nuclear physics and laser stimulation.

## Contribution

It provides a systematic analysis of electric field screening and enhancement in diatomic and polyatomic molecules across different frequency regimes, including resonance effects.

## Key findings

- Weak screening of low-frequency fields due to ro-vibrational states
- Microwave fields can be enhanced up to six orders of magnitude at resonance
- Derived general formulas for field screening in polyatomic molecules

## Abstract

According to the Schiff theorem, the atomic electrons completely screen the atomic nucleus from an external static electric field. However, this is not the case if the field is time-dependent. Electronic orbitals in atoms either shield the nucleus from an oscillating electric field when the frequency of the field is off the atomic resonances or enhance this field when its frequency approaches an atomic transition energy. In molecules, not only electronic, but also rotational and vibrational states are responsible for the screening of oscillating electric fields. As will be shown in this paper, the screening of a low-frequency field inside molecules is much weaker than it appears in atoms owing to the molecular ro-vibrational states. We systematically study the screening of oscillating electric fields inside diatomic molecules in different frequency regimes,i.e., when the field's frequency is either of order of ro-vibrational or electronic transition frequencies. In the resonance case, we demonstrate that the microwave-frequency electric field may be enhanced up to six orders in magnitude due to ro-vibrational states. We also derive the general formulae for the screening and resonance enhancement of oscillating electric field in polyatomic molecules. Possible applications of these results include nuclear electric dipole moment measurements and stimulation of nuclear reactions by laser light.