To move forward, we will need to switch our model from the two electrostatic spheres to a diatomic molecule.
Visualized above is an idealized diatomic system connected by a double bond. The double bond is composed of two bonds, the σ bond and the π bond.
Shown above is the π molecular orbital that corresponds to the π bond. There are other orbitals involved in this system. Be sure to explore sections on molecular orbitals to brush up on your knowledge on molecular orbitals.
Our simple diatomic molecule has a low molecular weight and a double bond (the second bond in the double bond is referred to as a π bond). Briefly, the π bond is formed due to an interaction between the atomic p-orbitals of each atom. The π bonding molecular orbital is formed along with a π* anti-bonding molecular orbital.
The system to the left has been simplified to show only the π and π* molecular orbitals when the atoms are close enough for bonding to take place. The atomic p-orbitals are shown at a distance where they are no longer interacting and forming a bond. An electron configuration energy diagram shows the approximate changes to the energy of the system.
You can click on the orbitals or energy levels on the energy diagram to see how the energy of the electron changes depending on what orbital is occupied. What other orbitals would you expect to find in a molecule with a double bond?
You will see a brief description and will be given a chance to jump directly to that topic
This topic is not currently available.
Physical chemistry attempts to understand chemistry through the physical world and using instrumentation.
Molecular excitation refers to the promotion of an electron to an excited state. This particular pheomenon is extremely important for current scientific discovery, particularly in the biological sciences.
A simple harmonic oscillator displays a very particular type of periodic motion called simple harmonic motion. A common example of a simple harmonic oscillator is a spring that is compressed or stretched.
Morse potentials are used to model the interaction between two atoms in a diatomic molecule.
A diatomic molecule has only two atoms which are connected through a chemical bond. This particular diatomic molecule is double bonded.
The energy of a diatomic molecule can be approximated using a Morse Potential. Quantum effects are not discussed.
The vibrational state of the diatomic molecule refers to the frequency at which the atoms oscillate (ie. the bond stretches and compresses).
A single rotational mode is available to the diatomic molecule and involves rotation around an axis that is perpendicular to the bond axis. The energy of the rotational mode is directly related to its angular momentum.
Electromagnetic radiation is a form of that travels in waves. Specifically, electromagnetic energy travels in a transverse wave that oscillates at a certain frequency.
Like other dipoles, the transition dipole refers to a difference in charge from one location of a molecule to another. The transition dipole occurs when an electron is excited from the ground state to an excited state.
The Jablonski diagram is capable of showing the transition between ground states and excited states by using quantized Morse potentials.
Fluorescence begins with absorption and molecular excitation into an excited state. Once promoted, the electron will fall to the lowest vibrational energy within that excited state.