Cadmium selenide quantum dots emit bright luminescence under UV excitation (He-Cd laser, for example). Absorption bands in the infrared are due to modes of vibrational excitation in water vapor. Raman scattering is the result of a virtual electronic state induced by the excitation light. Vibrational excitation can occur in conjunction with electronic excitation in the ultraviolet-visible region. One has to distinguish between quasi-resonant excitation and barrier excitation. Smith chart; impedance matching; pulse excitation. Muscarine binds with muscarinic acetylcholine receptors leading to the excitation of neurons bearing these receptors. The resulting cellular excitation causes neurons to fire excessively. Field weakening allows an electric machine to operate beyond the designed frequency of excitation. The phase of armature current varies with field excitation. Shock is a transient physical excitation. NMDA receptors have a very important role in modulating long-term excitation and memory formation. Normally, excitation and inhibition are balanced. Usually, the latter one is used in combination with a controlled parametric excitation. This uses multiple coils for excitation and reception.