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KIDA (for KInetic Database for Astrochemistry) is a project initiated by different communities in order to 1) improve the interaction between astrochemists and physico-chemists and 2) simplify the work of modeling the chemistry of astrophysical environments. Here astrophysical environments stand for the interstellar medium and planetary atmospheres. Both types of environments use similar chemical networks and the physico-chemists who work on the determination of reaction rate coefficients for both types of environment are the same.
For the interstellar medium, we provide chemical reactions occuring the gas-phase but also some parameters used to compute the interaction of species with the surface of interstellar grains and the chemical reactions occuring at the surface of these grains. We refer to Wakelam et al. (2010) and reference therein for a description of these processes. The types of data that are stored in KIDA are described here.
In KIDA, you can find different values for the same parameters from different bibliographic sources. In some cases, a quality indicator is also present. In addition to these reactions several chemical networks (a selection of reactions) specific for some astronomical objects are available. They can be directly from KIDA or compiled by users.

The KIDA database has been presented in the following scientific paper:
Wakelam et al. The Astrophysical Journal Supplement, Volume 199, Issue 1, article id. 21, 10 pp. (2012)

The following type of data can be found:

• Gas-phase reactions and associated partial rate coefficients (with detailed information)
• Polarizability, dipole moment and enthalpy of formation for some species.
• Desorption energies (from different types of surfaces) and diffusion energies (on different types of surfaces) for some species.
• Chemical reactions occuring at the surface of interstellar grains with branching ratios, activation energies and barrier width.

• You can find all existing data useful for the chemical modeling of interstellar chemistry and planetary atmospheres with detailed information.
• You can add data (reactions, rate coefficients, desorption energy, diffusion energy) to the database through csv templates.
• You can download a complete set of reaction rate coefficients and/or store your list of reactions.
• You can find information on the quality of the data and recommanded data for some of them.

The current administrator of the database is Pierre Gratier (Laboratoire d'Astrophysique de Bordeaux, France). Valentine Wakelam (Laboratoire d'Astrophysique de Bordeaux, France) works on the content of the database while Julien Penguen and Fabrice Mendes (Observatoire Aquitain des Sciences de l'Univers, France) are the web developers.
The experts in physics and chemistry who are working on the data present in KIDA are listed here.
If you have any comments or bug reports, please send an email to kida-obsu-bordeaux.fr.

You need to download templates in the csv format, fill out the file with your data and send it to us by email. For any addition of new channels or reactions, you need to add rate coefficients as well as a reference. Your data submitted to KIDA is sent to experts for validation.

No you cannot. If you need to do it, contact the KIDA team directly.

You can send an email to kidaobs.u-bordeaux1.fr and we will take care of the problem.

Quality indicators are of four types:

• Not recommended value
• Not rated value
• Valid value
• Recommended value

« Not recommended » means that either we have found a mistake in the data or there is a more accurate value to use. We do not erease any value from KIDA, this is why we use this indicator. « Not rated » means that we do not know. « Valid » is used for data with a proper reference (usually papers published by physico-chemists). « Recommended » is used for reactions that have been studied by KIDA experts and a datasheet explaining the recommendation is also available.

For most of the data (rate coefficient, desorption energies etc), the method is given. It can be:

• Measurement : this means that the data has been obtained experimentally.
• Theoretical : this means that the data has been theoretically computed.
• Review and evaluation : this means that the value is the result of a compilation of published data.
• Estimation : this means that it is a guess. This can be an educated guess though.

The different origins can be:

• Bibliographic : this means that the data was extracted from a bibliographic reference (paper, thesis, book) and the reference is provided.
• Other database : this means that the data was found in another database (usually without any bibliographic reference) and the name of the database is provided.
  • NIST Chemical Kinetics Database
  • OSU
  • UdFA
  • NIST COMPUTATIONAL CHEMISTRY COMPARISON AND BENCHMARK DATABASE
  • Burcat
• Datasheet : this is for recommended values.

Yes you can but you will be asked for all the information that has to appear in KIDA.

No, once a data has been accepted in KIDA, we never erase it. If a data appears to be wrong, we use the quality indicator.

If several data exist (from different groups for instance) for the same channel for the same or different ranges of temperature, they will all appear on the reaction page. On the seach result page, only the « best » value will appear.

You can find them here.

The answer is here.

See the answer here.

kida.uva.xxx networks are a selection of gas-phase chemical reactions extracted from KIDA that can be directly used in astrochemical models for the interstellar medium. These networks are regularly updated. The current versions are:

• kida.uva.2011 (Wakelam et al. The Astrophysical Journal Supplement, Volume 199, Issue 1, article id. 21, 10 pp. (2012))
• kida.uva.2014 (Wakelam et al. The Astrophysical Journal Supplement Series, Volume 217, Issue 2, article id. 20, 7 pp. (2015))

Masses: amu
Temperature: K
Dipole Moment: Debye
Rate coefficients for photo and cosmic-ray processes: s^-1
Rate coefficients for bimolecular reactions: cm³s^-1
Rate coefficients for termolecular reactions: cm⁶s^-1
Polarizability: ų
Enthalpy of formation and reaction: kJ mol^-1
Desorption energy: Kelvin
Diffusion energy: Kelvin
activation energy: Kelvin
Barrier Width (for surface reactions): Angstrom

In KIDA, there are four big famillies of reactions:

• Unimolecular reactions include dissociations and ionizations by cosmic-ray particules, secondary UV photons induced by cosmic-ray particles and direct UV photons. ITYPES 1 to 3.
• Bimolecular reactions includes all chemical reactions between two species. ITYPES 4 to 8
• Termolecular reactions are 3-body asssisted reactions.
• Surface reactions are reactions occuring at the surface of interstellar grains between adsorbed species.

ITYPE	Description
1	Dissociation or ionization of species due to direct collision with cosmic-ray particles.
2	Dissociation or ionization of species due to UV photons emitted following H2 excitation.
3	Dissociation or ionization of neutral species by UV photons with a standard interstellar UV field.
4	Neutral-neutral (A + B → C + D), ion-neutral (A+ + B → C+ +D, A- + B → C- + D), anion-cation (A+ + B- → C + D) reactions and associative ionization (A + B → AB+ + e-)
5	Exchange reaction A+ + B → A + B+ and A+ + B- → A + B
6	Association reactions between two species (neutral or ionized) stabilized by the emission of a photon (A + B → AB + photon or A+ + B → AB+ + photon).
7	Association of a neutral species and an anion, resulting in the ejection of the extra electron (A- + B → AB + e-).
8	Recombination of a positive ion with an electron resulting in the dissociation of the molecule (AB+ + e- → A + B) or the emission of a photon (AB+ + e- → AB + photon) or the attachment of the electron (A + e- → A- + photon)

Five different formula can be used to compute the rate coefficients from the parameters listed in KIDA.

Number (for export)	Name	Formula	Units
1	Cosmic-ray ionization		s-1
2	Photo-dissociation (Draine)		s-1
3	Modified Arrhenius		cm3 s-1
4	ionpol1		cm3 s-1
5	ionpol2		cm3 s-1
6	3-body	See here

For information on the ionpol1 and ionpol2 formula see here.
For information on the visual extinction Av see here.

The rate coefficients given in KIDA have been calculated for the standard interstellar radiation field cf. Draine (1978, ApJS, 36, 595). See also here.

Some explanations on the computation of the rate coefficients for unmeasured ion-polar reactions, i.e. using the ionpol1 and ionpol2 formula can be found here.

The pressure dependency of the rate coefficient is expressed as:

The broadening factor F is the factor by which the rate constant of a given recombination reaction at temperature T and at the reduced pressure Pr is reduced from the value it would have if recombination reactions behaved according to the Lindemann formula.
The reduced pressure Pr is compted by Pr =k0[M]/kinf with [M] the concentration of the third body.
k0 and k∞ are function of temperature computed with the Kooij formula. k0 is the low-pressure limiting form whereas kinf is the high-pressure limit. Both rate constants have the following unit: cm6.molecules-2.s-1.

The broadening factor F for every reduced pressures Pr is computed as:

c = - 0.4 - 0.67 x log10(Fc)
N = 0.75 - 1.27 x log10(Fc)
d = 0.14

In some cases, Fc can be calculated as a function of temperature from the Troe's fall-off parameters a, b, c, and d by:

a is dimensionless and b, c and d are in K (T as well of course).

When no specific Troe fall-off parameters can be retrieved from the literature, it can be assumed Fc = 0.64, following the simpler policy chosen by the NASA/JPL evaluation panel (Sander et al., 2006).
In KIDA, you will find Fc and the parameters to compute k0 and kinf.

In KIDA, we store 5 types of data for surface reactions: Two data specific to species:

• Binding energies
• Diffusion energies

For reactions, we store:

• branching ratios
• activation energies
• barrier width for surface reactions with activation energies to compute the rate coefficient with quantum tunneling (following the formula given in eq (6) of Hasegawa et al. 1992 http://articles.adsabs.harvard.edu/pdf/1992ApJS...82..167H for a rectangular barrier)

Concerning parameters for the surface reactions and gas-grain interactions, the available data is very sparse. So as a start, we have put in the database what we have been using in our models. A BIG work on quality data have just started.

We classify the surface types into hierarchical categories (see classification below). Data providers can nevertheless provide data for other surfaces by describing the method necessary to reproduce these surfaces.

• Photo-processes: Many information about the computation of the rates of photo-reactions can be found in Ewine van Dishoeck's web page at the University of Leiden (Netherlands): here.
• The ISSI Team: To improve our knowledge on the kinetic of cold interstellar regions, we made a group of both astrophysicists and physico-chemists. Two meeting of this group in Bern (Switzerland) were funded in 2008 by the International Space Science Institute (http://www.issibern.ch/). The results of our discussions have been written in an article submitted to Space Science Reviews and can be downloaded here.
• The UMIST Database for Astrochemistry (http://udfa.ajmarkwick.net/)
• The NIST webbook (http://webbook.nist.gov/chemistry/form-ser.html)