The excited state generally refers toElectron excited stateAfter atoms or molecules absorb a certain amount of energy, electrons are excited to a higher energy level but not ionized.When the gas is heatedMolecular kinetic energyIncrease, when liquid and solid are heatedMolecular vibrationEnergy increases, but no electrons are excited. These states are not excited states.When an atom or molecule is in an excited state,Electronic cloudSome changes will occur in the distribution of, and the distance between equilibrium nuclei of molecules will increase slightly,chemical reactionThe activity increases.AllPhotochemical reactionThey are chemical reactions carried out after the molecules are promoted to the excited state, sophotochemistryAlso called excited state chemistry.ionizing radiation(orelectromagnetic radiation）When the energy transferred to atoms or molecules is lower than itsIonization potentialAnd enough to makeElectron transitionAt higher energy levels, the atom or molecule is in an excited state.Sum of excited statesground stateHave differentpotential energyCurve and balance core spacing.
After atoms or molecules absorb a certain amount of energy, electrons are excited to a higher energy level but not yet ionized.
Generation method
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excited state
Mainly:
①Photoexcitation。The atom or molecule in the ground state can jump to the excited state after absorbing a certain energy photon, which is the main method to generate the excited state.
③ Energy transfer and quenching (excited molecules willenergy transferTo another ground state molecule and excite it).
energy dissipation
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Physical pathway
Molecules in excited state are unstable, and energy should be attenuated in various ways. Excited stateenergy dissipation The physical path of is shown in figure.
Excited state molecules haveChemical bondWhen the excitation energy of dissociation energy is used, it will dissociate into molecular fragments, and the part exceeding the dissociation energy of chemical bond will become the kinetic energy of molecular fragments.Through the transfer of excitation energy between molecules, the excited ground state complex will be formedelectron transfer And chemical reactions (such as addition, dehydrogenation).
