This article describes the natural science term. For "activation" as it refers to computer software, see product activation.

Activation in science generally refers to the process whereby something is prepared or excited for a subsequent reaction.

Chemistry

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For example, in chemistry, activation of molecules is a required for a chemical reaction to occur. The phrase energy of activation ^*, refers to the energy the molecules must acquire before they can successfully react with each other reactants to produce the products. The energy needed for activation can be quite small and the molecules may have enough energy just from thermal fluctuations the molecules naturally have (i.e. lots of reactions don't have to be heated to proceed).

Biochemistry

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Similarly, neutron activation is a standard analytical technique used to analyze for elements, usually, metals. The sample is placed in a high neutron flux and in the nuclear reaction involved, a neutron is captured by a nucleus. If the resulting new isotope is unstable, it will undergo radioactive decay. This decay can be monitored and the element emitting identitified by the identity and energy of the emitted particles. Prompt Gamma Activation Analysis (PGAA) is a rapid, nondestructive, instrumental, nuclear technique which is used for trace and major component analysis of various elements.

Science

Activation