excitation

n. act of causing excitement, stimulation; excited state, stimulated state

Excitation is an elevation in energy level above an arbitrary baseline energy state. In physics there is a specific technical definition for energy level which is often associated with an atom being excited to an excited state.In quantum mechanics an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum). The temperature of a group of particles is indicative of the level of excitation.
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Excitation /ex·ci·ta·tion/ 1. irritation or stimulation. 2. the addition of energy, such as excitation of a molecule by absorption of photons. [more]Excitation - Community and Resources

Noun
1. the state of being emotionally aroused and worked up; "his face was flushed with excitement and his hands trembled"; "he tried to calm those who were in a state of extreme inflammation"
(synonym) excitement, inflammation, fervor, fervour
(hypernym) emotional arousal
(hyponym) fever pitch
(attribute) exciting
(derivation) stimulate, excite, stir
2. the neural or electrical arousal of an organ or muscle or gland
(synonym) innervation, irritation
(hypernym) arousal
(derivation) excite
3. something that agitates and arouses; "he looked forward to the excitements of the day"
(synonym) excitement
(hypernym) arousal, rousing
(hyponym) hair-raiser, chiller
(derivation) stimulate, excite

n. excitation, excitement; effervescency, anticipation