An article from the Kazan Federal University and the Tatarstan Academy of Sciences saw A.
The ionization energy is one of the most important physico-chemical parameters. It is defined as the amount of energy required to tear an electron from an atom. The dependence of the ionization energy on the atomic number determines the periodic law of the chemical elements, which is assumed to be fundamentally constant. Based on the previously predicted effect of changing electron mass, the research team showed that the ionization energy of atoms in photonic crystals with an ultra-high index of refraction can be changed significantly.
Photonic crystals are media with periodically changing electromagnetic properties. An example of a photonic crystal is a dense packing of dielectric microspheres with an empty space between them. The size of these cavities is large enough to view an electron or atom placed there that is free from interactions with the material of the walls. However, the environment of photonic crystals indirectly influences the properties of particles by modifying their own radiation field.
The fact is that, according to the modern world view, all particles are involved in vacuum quantum fluctuations. In particular, an electron constantly creates virtual photons and immediately destroys them. It turned out that photonic crystals can influence this interaction. Traditionally, this question has only been investigated for electrons bound in an atom. An atom involved in such a process receives a correction in its energy called the Lamb Shift, which is very small in relation to the atomic energies themselves, even when the atom is arranged in photonic crystals.
The reason no one has considered the quantum fluctuations of a free electron in a photonic crystal is that its mass in this state is infinite. The fact is that due to the interaction with vacuum, the mass of a free electron must receive a correction, which is called electromagnetic mass. This correction is added to the “bare” mass of the electron and forms its actually observed mass.
However, calculations in the first half of the 20th century showed that the integrals in the formulas for electromagnetic mass diverge. To get around this problem, the physicists developed a method for renormalizing the mass, in which the electromagnetic mass was ignored and in all other formulas the “bare” mass of the particle was replaced by the observed mass. This paved the way for quantum electrodynamics, the predictions of which are confirmed with high accuracy in experiments under normal conditions.
However, if photonic crystals affect the interaction with a vacuum, this should be reflected in the electromagnetic mass and consequently in the electron mass actually observed. The researchers showed that in this case a final correction occurs, which is the difference between the electromagnetic masses of an electron in a photonic crystal and in a vacuum. In addition, due to the anisotropy of the photonic crystal, the mass depends on the direction in which the electron is flying. This causes an electron bound in an atom to have new energy corrections that depend on its state. It turned out that for very high indices of refraction of the substance making up the photonic crystal, these corrections are comparable to the energies of transitions between planes, including the energies of ionization transitions.
In this work they calculated corrections to the ionization energy of hydrogen and alkali atoms, which are arranged in the cavities of a one-dimensional photonic crystal made of materials with an ultra-high refractive index. It turned out that the decrease in ionization energy in the case of the cesium atom can reach 68 percent.
The predicted effect is of great importance for basic physics as well as for applied physics and chemistry. In particular, a method for manipulating the electromagnetic mass was proposed for the first time. In addition, the effect enables the periodic law of chemical elements to be influenced, and the change in ionization energy can be used to synthesize new chemical compounds and to produce drugs based on them.
In the future, the team plans to work with major pharmaceutical centers and explore the possibility of its use in the synthesis of new compounds. An experimental verification of the effect can be done by measuring the rate of a chemical reaction that occurs in the gas phase between the walls of a one-dimensional photonic crystal. They also want to calculate the ionization energy correction for other chemical elements.