An important discovery - with no electric field, the center of the electron cloud of K atom does not coincide with the nucleus

TL;DR

This study reveals that potassium atoms have a permanent electric dipole moment and are polar, challenging the common assumption that atoms without external fields are non-polar, with implications for time-reversal symmetry.

Contribution

The paper provides experimental evidence that ground state potassium atoms possess a large permanent electric dipole moment, indicating they are polar and exhibit time-reversal violation.

Findings

Potassium atoms have a permanent EDM of 2.53×10^-29 C·m.

K atoms behave as polar molecules with susceptibility proportional to density and inversely to temperature.

Linear Stark effect in K atoms is too small to observe directly.

Abstract

It is a general point of view that in the absence of an external field, the nucleus of an atom is at the center of the electron cloud, so that all kinds of atoms do not have permanent electric dipole moment (EDM). In the fact, the idea is untested. Using two special capacitors containing Potassium vapor we discovered that the electric susceptibility Xe of K atoms is directly proportional to the density N, and inversely to the temperature T, as polar molecules. The experimental K material with purity 0.9995 is supplied by Strem Chemicals Co. USA. We have distinguished between permanent and induced dipole moments carefully. There is good evidence that a ground state neutral K atom is polar atom and has a large permanent EDM, d (K) =2.53\times10-29C.m. New example of time-reversal violation occurred in K atoms. Why has the linear Stark effect of K atoms not been observed? The article discussed the question thoroughly. The most linear Stark shift of K atoms is only 0.0041nm. It is so small, in fact, that a direct observation of the shifts is not possible! These results can be repeated in other laboratories. Our experimental apparatus are still kept, we welcome anyone who is interested in the experiments to visit and examine it.