Preferred Label : adiabatic;
IUPAC definition : This word is used with various different meanings, and when it is used it should be
defined. In thermodynamics 'adiabatic' is used in a macroscopic sense to refer to
a process occurring in a thermally insulated system, so that there is no flow of heat
to or from the surroundings. In reaction dynamics, the word has been used in a microscopic
sense, with a range of meanings which have only a tenuous relationship to the thermodynamic
meaning or the etymology. Whereas the thermodynamic meaning relates to conditions
imposed on a process by an observer, the microscopic meaning relates to conditions
under which the process occurs naturally. The microscopic meanings, as used in reaction
dynamics, all have in common the feature that quantum states remain unchanged during
the course of reaction. Different quantum states may be referred to: A reaction that
is not adiabatic is referred to as nonadiabatic or diabatic, and some workers make
a distinction between the two words. ol li A reaction in which there is no change
of electronic state or multiplicity has been called adiabatic, or more specifically
electronically adiabatic. /li li A reaction in which there is no change of vibrational
state during the course of reaction has been said to be vibrationally adiabatic. More
loosely, the expression has been applied to a process in which excess vibrational
energy in the reactants appears as vibrational energy in the products, or in which
ground-state vibration in the reactants leads to ground state vibration in the products.
/li li A reaction in which excess rotational energy in the reactants appears as rotational
energy in the products, or in which ground-state rotation in the reactants leads to
ground-state rotation in the products, has been referred to as rotationally adiabatic.
/li li In the Rice–Ramsperger–Kassel–Marcus (RRKM) theory of unimolecular reactions,
a degree of freedom whose quantum number is more or less preserved during energization
and subsequent reaction has been called 'adiabatic'; the word 'inactive' has also
been applied to it. /li /ol ;
Origin ID : A00141;
See also
This word is used with various different meanings, and when it is used it should be
defined. In thermodynamics 'adiabatic' is used in a macroscopic sense to refer to
a process occurring in a thermally insulated system, so that there is no flow of heat
to or from the surroundings. In reaction dynamics, the word has been used in a microscopic
sense, with a range of meanings which have only a tenuous relationship to the thermodynamic
meaning or the etymology. Whereas the thermodynamic meaning relates to conditions
imposed on a process by an observer, the microscopic meaning relates to conditions
under which the process occurs naturally. The microscopic meanings, as used in reaction
dynamics, all have in common the feature that quantum states remain unchanged during
the course of reaction. Different quantum states may be referred to: A reaction that
is not adiabatic is referred to as nonadiabatic or diabatic, and some workers make
a distinction between the two words. ol li A reaction in which there is no change
of electronic state or multiplicity has been called adiabatic, or more specifically
electronically adiabatic. /li li A reaction in which there is no change of vibrational
state during the course of reaction has been said to be vibrationally adiabatic. More
loosely, the expression has been applied to a process in which excess vibrational
energy in the reactants appears as vibrational energy in the products, or in which
ground-state vibration in the reactants leads to ground state vibration in the products.
/li li A reaction in which excess rotational energy in the reactants appears as rotational
energy in the products, or in which ground-state rotation in the reactants leads to
ground-state rotation in the products, has been referred to as rotationally adiabatic.
/li li In the Rice–Ramsperger–Kassel–Marcus (RRKM) theory of unimolecular reactions,
a degree of freedom whose quantum number is more or less preserved during energization
and subsequent reaction has been called 'adiabatic'; the word 'inactive' has also
been applied to it. /li /ol
