ASC vocabulary: sub-category of fundamental parameter

[lisemurberg]

From meeting 1. Dec 2023 on ASC vocabulary:

Include "rate constant" etc as a sub-category of "Product type" -> "Fundamental parameter" -> "rate constant" +++.

@brissebrat Can you include a list of elements that should be under fundamental paramenter?

[brissebrat]

• Complex Refractive Index (CRI)
• Gas Phase Rate Constant
• Growth Factor
• Mass absorption coefficient (MAC)
• Mass extinction coefficient (MEC)
• Mass scattering coefficient (MSC)
• Photolysis Frequency
• Quantum Yield
• Single Scattering Albedo (SSA)
• Secondary Organic Aerosol (SOA) Yield
• Vapor Pressure

[markusfiebig]

From an ACTRIS vocabulary perspective, the concepts mentioned above are properties of interest. They will therefore be included as such, and a link placed to also identify them as fundamental constant. Benedicte to provide definitions.

[markusfiebig]

Questions:

• Why do we limit rate constant to the gas phase?

All others have been included preliminarily without definition.

[markusfiebig]

From Benedicte:

Gas-phase rate constant: In chemical kinetics, a reaction rate constant (denoted k) is a proportionality constant which quantifies the rate of a chemical reaction by relating it with the concentration of reactants. First-order gas-phase rate constants (A -> products) are expressed in s-1. Second-order rate constants (A+B -> products) are expressed in cm3 molecule-1 s-1. Third-order rate constants (A+B+C -> products) are expressed in cm6 molecule-2 s-1.

Secondary organic aerosol yield:

Photolysis frequency: The photolysis frequency (denoted J) is the equivalent of a rate constant for the photodissociation process: A + h\nu -> products. It is expressed in s-1. It is expressed as: J=∫_λ1^λ2▒〖F(λ)×ϕ(λ)×σ(λ)〗 Where F() is the actinic flux, () is the quantum yield, () is the absorption cross section.

Quantum yield: the quantum yield (denoted Φ) of a radiation-induced process is the number of times the process, here the photodissociation, occurs per photon absorbed by the system: Φ(λ)=(number of photodissociations)/(number of photons absorbed) Quantum yield is unitless.

Mass absorption coefficient: The mass absorption coefficient is the ratio of the light absorption coefficient, integrated over a unit volume to the mass of a target object, integrated over the same unit volume. It is expressed in m2/g.

Mass extinction coefficient: The mass extinction coefficient is the ratio of the light extinction coefficient, integrated over a unit volume to the mass of a target object, integrated over the same unit volume. It is expressed in m2/g.

Mass scattering coefficient: The mass scattering coefficient is the ratio of the light scattering coefficient, integrated over a unit volume to the mass of a target object, integrated over the same unit volume. It is expressed in m2/g.

Complex refractive index: the complex refractive index is a complex number (CRI=n-ik) representing the capacity of particles to interact with radiation. The real part (n) is related to the aerosol non−absorbing component, while its imaginary part (k) to the absorbing one. It is unitless.

Single scattering Albedo: the Single Scattering Albedo is the ratio between the volume scattering and extinction coefficients (extinction=scattering+absorption). It is unitless. Vapor pressure: Vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system.

Growth factor: Hygroscopic growth factor (GF) of aerosols is related to water loading on particles in sub-saturated conditions. It is calculated as the ratio of the diameter of the particle after exposition to a given relative humidity to the diameter of the particle before exposition. Growth factor is unitless.