Astrochemistry and Molecular Astrophysics

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Bas Braams

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Aug 14, 2013, 11:58:39 AM8/14/13
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Greetings! Allow me to be the first user to post to this group.

Under the main topic Interdisciplinary Astronomy there is a subtopic Astrochemistry and a subtopic Molecular Astrophysics, among other subtopics. I wonder what is the difference between the two. If it is explained to me then I wonder if I'll be able to remember it. In other words, I suspect that over time these two topics will blend, and it seems appropriate to me to merge them at the start, or change the names to emphasize the difference. Maybe Molecular Astrophysics is meant as the home for Astrophysical Spectroscopy? If one of the subtopics is chemistry and the other is spectroscopy then I can learn the distinction. If one is chemical physics and the other is physical chemistry then I am not so sure.

Katie Frey

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Sep 4, 2013, 12:27:50 PM9/4/13
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Hi Bas,

This is definitely the kind of input we are looking for; to understand what each term means and how they relate (or should relate) to other terms.  If there is a good distinction between these terms in particular then that information would be included in the term scope notes, to help guide users and editors.  If not, then we would look into a way to merge the terms and their sub-branches.

Either way this is a question we would want our editors to discuss.  We are still searching for a good place to have and track those discussions, but in the meantime if anyone else on the list has thoughts on this we can have the conversation here.  Once we have a management system in place, we will make sure this question is addressed.

Thanks again for your comments!

Katie

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Katie E. Frey
John G. Wolbach Library
Harvard-Smithsonian Center for Astrophysics
60 Garden Street, MS-56, Cambridge, MA 02138
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617-496-7579

http://astrothesaurus.org
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http://www.adsabs.harvard.edu/

Bas Braams

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Sep 11, 2013, 3:28:30 AM9/11/13
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Further to the topic of atomic and molecular (A+M) processes in astrophysics I like to a point to a relevant classification scheme that was developed in 2003 for A+M processes in plasma. The scheme also contains classifiers for particle-material interaction. Please find it here:

D. Humbert, Yu. Ralchenko, P. Krstic and R. E. H. Clark, "Classification of Processes, Version 1.2, 7 October 2003", IAEA Atomic and Molecular Data Unit, unpublished.

As explained in the introduction there it was produced in order to synthesize classifications used in on-line databases CFADC, AMBDAS and GAPHYOR. For convenience I reproduce the classification here in plain text format. Note that it is not presented as exactly a Thesaurus. One would probably want to remove the three-letter codes, and then one has to disambiguate some terms (e.g. Recombination) that occur under two or more headings. Treat the non-bold terms as NT1 refinements of the bold terms for the purpose of a Thesaurus. I have a few further comments at the bottom.

Structure and Spectra

SGN - General
SLS - Line broadening, shapes and shifts
SIA - Interatomic Potentials
SPM - Polarizabilities, Electric Moments
SEW - Energy Levels and Wavelengths
STP - Transition Probabilities and Oscillator Strengths
SSM - Potential Curves and Structure of Molecules
SDP - Dynamic Polarizability
SIR - Infrared Spectra
SVS - Visible Spectra
SUV - UV/VUV/XUV Spectra
SXR - X-Ray Spectra
SRS - Rotational Spectra
SVB - Vibrational Spectra
SAI - Autoionization
SAD - Autodetachment
SDS - Autodissociation
SMM - Magnetic Moments 
SHF - Hyperfine Structure 
SIE - Isoelectronic Sequences 
SFT - Forbidden Transitions 
SQE - QED Effects 
SRP - Relaxation Processes 
SIP - Ionization Potentials 
SRY - Rydberg States

Photon-Particle and Field-Particle Interactions

PGN - General
PTS - Total Absorption, Scattering
PDS - Photodissociation
PES - Elastic Scattering
PMA - Multiphoton Absorption (excitation and ionization)
PDT - Photodetachment
PFL - Fluorescence
PEX - Photoexcitation
PIN - Photoionization
PFF - Free-Free Absorption or Inverse Bremsstrahlung
PEA - Effective Absorption, Total Diffusion
PTA - True Absorption
PAD - Angular Diffusion (scattering)
PED - Elastic Diffusion (Thomson, Rayleigh)
PNL - Non-linear Effects
PZE - Zeeman Effect
PSE - Stark Effect
PGF - General Electromagnetic Field
PTF - Interaction with Time-Varying Fields

Electron-Heavy Particle Interactions

EGN - General
EAS - Angular Scattering
EBS - Bremsstrahlung
EDX - Deexcitation
EEL - Elastic Scattering
ELB - Line Broadening, Shapes and Shifts
ETS - Total Scattering
EDT - Detachment
EFL - Fluorescence
EEX - Excitation, Change of Excitation
EIN - Ionization
EMI - Multiple Ionization
ENI - Negative Ion Formation
EMT - Momentum Transfer, Transport Cross-Sections
EUP - Unknown Products
EDP - Depolarization, Change of Polarization
EIP - Creation of an ion pair (positive-negative)
ERC - Recombination (general)
ERR - Radiative Recombination
ERD - Dielectronic Recombination
ERT - 3-body Recombination
ERO - e-i-o Recombination
EDC - Dielectronic Capture
EDS - Dissociation
EDR - Dissociative Recombination
EDA - Dissociative Attachment
EDE - Dissociative Excitation
EDI - Dissociative Ionization

Heavy Particle-Heavy Particle Interactions

HGN - General
HAS - Association
HLB - Line Broadening, Shapes and Shifts
HDS - Dissociation
HDX - Deexcitation
HES - Elastic Scattering
HCX - Charge Transfer
HUP - Unknown Products
HAS - Angular Scattering (sic, also Association)
HIR - Interchange Reactions
HEL - Inelastic Energy Losses
HET - Energy Transfer
HIP - Interaction Potentials
HRC - Recombination
HTS - Total Scattering
HDT - Detachment
HFL - Fluorescence
HEX - Excitation
HIN - Ionization
HPN - Penning Ionization
HST - Stripping (of projectile)
HAT - Attenuation
HXT - Excitation Transfer
HAI - Associative Interchange Reactions
HDI - Dissociative Interchange Reactions
HDC - Dissociative Charge Transfer
HMN - Mutual Ion-Ion Neutralization

Particle-Matter Interactions

MGN - General 
MAC - Accomodation 
MAD - Adsorption 
MCR - Chemical Reactions 
MDE - Desorption 
MRE - Reemission 
MRF - Reflection 
MSD - Surface Damage 
MSE - Secondary Electron Emission 
MIR - Radiation Induced by Particle Impact on Surfaces 
MNE - Neutralization, Ionization, Dissociation 
MSP - Sputtering 
MRS - Radiation-Enhanced Sublimation 
MTD - Trapping, Detrapping 
MPE - Photoelectric Ejection of Electrons 
MEL - Energy Loss and Stopping Power 
MPR - Particle Range 
MMS - Multiple Scattering 
MCP - Charge State Population 
MEP - Excited State Population 
MRH - Reflection of Heavy Particles from Surfaces 
MRL - Reflection of Electrons from Surfaces

Data Compilations

DGN - General 
DEH - Electron-Heavy Particle Interactions 
DHH - Heavy Particle-Heavy Particle Interactions 
DPF - Photon-Particle and Field-Particle Interactions 
DSS - Structure and Spectra 
DTP - Transport Properties 
DPM - Particle-Matter Interactions

Bibliography

BGN - General 
BEH - Electron-Heavy Particle Interactions 
BHH - Heavy Particle-Heavy Particle Interactions 
BPF - Photon-Particle and Field-Particle Interactions 
BSS - Structure and Spectra 
BTP - Transport Properties 
BPM - Particle-Matter Interactions

Further comments by BJB.

At the top level of this classification the items Photon-Particle and Field-Particle Interactions, Electron-Heavy Particle Interactions, Heavy Particle-Heavy Particle Interactions, and Particle-Matter Interactions characterize the incoming channel of the reaction and the next level in the classification describes the process or outcoming channel. The description of the incoming channel could of course be refined (heavy-heavy reactions can be refined into atom-atom, atom-molecule, molecule-molecule, and then further by charge of the involved particles). The reason that this was not done will lie in the intended application of this classification to a specific collection of databases. In those databases one searches by reactants and by process; so, for example, one searches for collisions of (e-) with (N2)+, and process dissociative ionization. There is no need for a specific category of, say, Electron-(Positive Molecular Ion) Collisions if the user is anyway specifying the reactants.

Without reproducing it here I also point to the process codes developed by the Virtual Atomic and Molecular Data Centre (VAMDC) for use with the XML Schema for Atoms, Molecules and Solids (XSAMS):

XSAMS process codes for VAMDC; VAMDC-XSAMS Reference Guide (version 1.0, release 12.07):
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