The key difference between vibrational relaxation and internal conversion is that vibrational relaxation is the relaxation of an electron that occurs in an electronic state and moves from a high to low vibrational energy level, whereas internal conversion is the movement or relaxation of an electron from a higher to lower electronic state via emission of heat.
Typically, the processes of vibrational relaxation and internal conversion leave an excited molecule (by means of electronics) in the lowest possible vibrational sublevels of the initial singlet excited state. Moreover, the relaxation process can be either endothermic or exothermic. The electron excitation of molecules can be a result of the absorption of near UV or visible light.
CONTENTS
1. Overview and Key Difference
2. What is Vibrational Relaxation
3. What is Internal Conversion
4. Vibrational Relaxation vs Internal Conversion in Tabular Form
5. Summary – Vibrational Relaxation vs Internal Conversion
What is Vibrational Relaxation?
Vibrational relaxation is the movement of an electron that occurs in an electronic state from a high vibrational energy level to a lower energy level for its relaxation. It occurs when an excited electron gives some of its vibration energy to a different electron that is in the same or a different molecule. This occurs in the form of kinetic energy. Vibrational relaxation can be used to follow specific molecules in time. Pump-spectroscopy is another method that can be used for the same requirement.
Vibrational relaxation is an endothermic process. Therefore, it can cause the gas temperature to decrease alongside the direction of flow. Typically, vibrational relaxation occurs in about 10-12s and it is the loss of excess energy to inelastic collisions with solvent molecules.
What is Internal Conversion?
Internal conversion is the movement of an electron from a higher to a lower electronic state for its relaxation via the emission of heat. It is a non-radioactive decay process where a nucleus is excited electromagnetically. This happens along with one of the orbital electrons of an atom. It can cause the emission of an electron from an atom.
Therefore, this process is a high-energy electron emission from a radioactive atom but not from the nucleus. This leads the high-speed electrons that are coming from internal conversion to be not called beta particles. Moreover, internal conversion is possible when gamma decay is possible. But the atom is completely ionized.
What is the Difference Between Vibrational Relaxation and Internal Conversion?
Vibrational relaxation and internal conversion are important electron excitation-related processes. The key difference between vibrational relaxation and internal conversion is that vibrational relaxation is the relaxation of an electron that occurs in an electronic state and moves from a high to low vibrational energy level, whereas internal conversion is the movement or relaxation of an electron from a higher to lower electronic state via emission of heat. In addition, vibrational relaxation is an endothermic movement, while internal conversion is an exothermic movement.
The below infographic presents the differences between vibrational relaxation and internal conversion in tabular form for side-by-side comparison.
Summary – Vibrational Relaxation vs Internal Conversion
Vibrational relaxation is the change in the occurrence of an electron between two vibrational energy levels, while internal conversion is the change in the occurrence of an electron between two electronic states. The key difference between vibrational relaxation and internal conversion is that vibrational relaxation is the relaxation of an electron that occurs in an electronic state and moves from a high to low vibrational energy level, whereas internal conversion is the movement or relaxation of an electron from a higher to lower electronic state via emission of heat.
Reference:
1. “Vibrational Relaxation.” An Overview | ScienceDirect Topics.
Image Courtesy:
1. “Nuclear Reaction” By Kjerish – This file has been extracted from another file (CC BY-SA 4.0) via Commons Wikimedia
2. “Electronic Processes Involving Light” By Jacobkhed – Own work (CC BY-SA 3.0) via Commons Wikimedia