Atomic electron transition

In atomic physics and chemistry, an atomic electron transition is when an electron moves from one energy level to another inside an atom or an artificial atom. These energy levels are fixed and unique for each atom, creating special gaps between them. Scientists use these unique energy gaps to identify and study different atoms in samples using tools like energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy.

Electrons can lose energy by releasing electromagnetic radiation in the form of a photon, moving to a lower energy level. They can also gain energy by absorbing photons, which lifts them to a higher energy level. The bigger the gap between the energy levels, the shorter the wavelength of the photons involved. This process helps scientists understand the structure and behavior of atoms.

History

In 1913, a scientist named Niels Bohr suggested that electrons can jump between different energy levels in an atom. Later, James Franck and Gustav Ludwig Hertz showed through experiments that atoms really do have these special energy levels.

In 1975, another scientist named Hans Dehmelt said that we might one day see these jumps. In 1986, scientists finally saw these jumps for the first time using trapped atoms of barium and mercury.

Theory

An atom can interact with a moving electric field. This interaction happens when the atom is exposed to radiation, like light. In simple terms, the atom’s tiny parts can move from one energy level to another because of this interaction.

The way this interaction works can be described using special math rules. One important rule helps us understand how often these moves between energy levels happen. This rule is called Fermi’s golden rule. It tells us that the chance of an atom’s part moving depends on certain factors, like the strength of the electric field and whether the move follows the atom’s selection rules. These rules decide which moves are allowed.

E ( t ) = | E 0 | R e ( e − i ω t e ^ r a d ) {\displaystyle E(t)=|{\textbf {E}}_{0}|Re(e^{-i{\omega }t}{\hat {\textbf {e}}}_{\mathrm {rad} })}

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Electromagnetic radiation interactions

To move an electron to a higher energy level in an atom, a piece of light called a photon must give the electron just the right amount of energy. This energy is similar to the strength of ultraviolet (UV) and X-ray light. Special tools like UV and X-ray lasers can be used to study these movements of electrons.

When an electron moves back down to a lower energy level, it can give off this energy in the form of light. We can use different methods to detect this light and learn about the atoms in a sample. For example, shining UV or visible light on a sample can show us how much light passes through or is blocked, helping us understand what the sample is made of.

Recent discoveries

In 2019, scientists did an experiment using a special kind of artificial atom made from two transmon qubits placed in very cold temperatures of 15 mK. They found that some changes in energy happen in a smooth, steady way and can even be reversed. But other changes are hard to predict.