Zwischenzustände

Zwischenzustände (singular: Zwischenzustand) are intermediate or transitional states that occur between well-defined conditions in a process. The term combines Zwischen- 'between' and Zustand 'state'. It is used across disciplines to describe temporary, often non-stable conditions that lie between the initial and final states of a system. In everyday language it can refer to any phase of change that is not the end state.

In chemistry, Zwischenzustände describe species that appear during a reaction but are not final products. These are called reaction intermediates, such as short-lived carbocations, free radicals, or transient metal complexes. In many contexts there is also a related concept of the transition state (Übergangszustand), a high-energy configuration along the reaction coordinate that cannot be isolated but governs the rate of conversion from reactants to products.

In physics and spectroscopy, Zwischenzustände refer to transient energy levels or configurations that occur during absorption, emission, or scattering processes. They may be populated briefly before decaying to lower states. The term is sometimes used loosely to describe virtual or metastable states in theoretical discussions.

In computer science and systems theory, Zwischenzustände can denote intermediate states in state machines, process workflows, or dynamic models, representing steps that are not final but necessary for transitioning from one condition to another.

See also: intermediate state, transition state, metastable state, reaction intermediate, state machine.