Excitation vs Absorption
Excitation is the change of the state of a system to a higher energy. Absorption is the energy transfer from a photon to a system. The terms absorption and excitation are widely used in the fields of quantum mechanics, analytical chemistry, relativity and many others. A very good understanding in these terms is required in order to understand the content of these fields properly. The concepts of absorption and excitation are some of the foundation concepts in the field of spectroscopy and spectrometry. In this article, we are going to discuss what absorption and excitation are, their definitions, applications of absorption and excitation, the similarities of absorption and excitation and finally the difference between absorption and excitation.
What is Absorption?
Absorption is a term generally used to identify some quantity becoming a part of another quantity. In this article, we are going to discuss absorption in the sense of electromagnetic waves. The absorption of electromagnetic waves refers to the transferring process of the energy of the photon to the system in which the photon has been absorbed. In the process of absorption, the incident photon is lost. Let us take a system with a single electron bound to the nucleus. Assume that the electron in the ground state. If a photon collides with the electron, the electron can absorb the photon depending on the energy of the photon. If the energy of the photon is equal to the energy difference between the ground state and some other state, the electron can absorb the photon. If the energy of the photon is not equal to an energy gap, the photon will not be absorbed. The photon has initial momentum due to the mass of the photon. This causes a momentum change of the electron when the photon is absorbed. Absorption is the founding principle of the absorption and emission spectra.
What is Excitation?
Excitation is the transfer of a system that is at a low energy state to a state of high energy. Assume an electron bound to the nucleus at the ground state. The quantum mechanics suggests that the electron can only take specific energy states. The probability of finding the electron in between these stationary states is zero. Therefore, the energy differences between two stages are discrete values. This means an electron can absorb or emit energies corresponding to any difference between stationary states, but not in between. Excitation is the process of absorbing such a photon to go up to a higher energy level. The opposite process of excitation is emitting a photon to come down to a lower energy level. If the energy of the incident photon is sufficiently large enough, the electron will move to a very large energy state thus removing itself from the atom. This is known as ionization.
What is the difference between Excitation and Absorption?
• Absorption is the process of transferring energy from a photon to a certain object.
• Excitation is the process of absorbing a photon and moving into a higher energy level.
• For excitation to occur, absorption must happen, and if absorption takes place, the system must be excited. Therefore, absorption and excitation are mutual processes.