What is duplet state?

A duplet state is a quantum state of a system with two particles, such as two electrons, two protons, or two neutrons, in which the spins of the two particles are aligned. This means that the total spin of the system is either +1 or -1, depending on whether the spins of the two particles are parallel or antiparallel.

Duplet states are important in chemistry because they can affect the properties of molecules. For example, the presence of a duplet state can lead to increased chemical reactivity or stability. They also play a role in spectroscopy, as the energy difference between a duplet state and a singlet state (in which the spins of the two particles are opposite) can be measured using techniques such as electron spin resonance (ESR).