View source for ASMS 1984

<big><big>ASMS Committee on Nomenclature</big></big>

<big>San Antonio, 1984</big>

The meeting of the Nomenclature Committee was held on May 26, 1984, and it was attended by 10 people including the Chairman. The Chairman gave a brief history of the actions of the Committee since 1979.  The history was deduced from reports of the Committee meetings published in the Bound Volumes from 1979 through 1983.	It was particularly pointed
out that 370 and expressions referring to mass spectrometry have been defined and given in these issues of the Bound Volume, and it may be concluded that the Committee has been very active. It was also deduced from the report of the 1983 meeting of the Committee that action was required at the 1984 meeting on the terms listed on [[ASMS_1983#Definitions_for_Consideration:|p. 970 of the 1983 Bound Volume]] under the heading, "Definitions for Consideration" and on the 58 terms given on pp. 904-909 of the 1982 Bound Volume starting with the terms under the heading "Secondary Ion Mass Spectrometry."

The Committee voted to accept all of the terms under consideration on p. 970 of the 1983 Bound Volume with the exception of the definition of Preformed Ions, which was deleted as being obvious and unnecessary. A small editorial change was made on Lhe definition for Average Mass. The Chairman regrets that the maker and seconder of the motion on these matters was inadvertently not recorded.

It was moved by J. Yergey and seconded .by J. Hiller not to accept any of the terms referring to Secondary Ion Mass Spectrometry given on
pp. 904-907 of the 1982 Bound Volume. The motion carried. However, in addition it	moved by T. Lehman and seconded by K. Busch that these terms and their definitions be given to the organizers of the conference on secondary ion mass spectrometry going to be held this Fall. The motion carried, and the Chairman asked Dr. Lehman to undertake theaction called for by the motion. He agreed to do this.

In the material received by the Chairman from the previous Chairman was a list of 268 terms relating to computers and computer technology. The correspondence examined by the Chairman seemed to imply that these terms should be considered at the 1984 meeting of the Committee.
Consequently they were examined with as much care as was possible given the very large number of terms and the relatively limited time of the meeting. It was moved by H. Fales and seconded by J. Yergey that these terms not be accepted by the Committee. The motion passed unanimously.

It was moved by J. Watson and seconded by J. Yergey that the Chairman bring together all of the terms which have appeared in the Bound Volumes through 1983 (and including those approved at this meeting) to make one . complete list for easy reference by members of ASMS and mass spectrometrists in general.	The Chairman agreed to do this, and the resulting list is included as pa.t of this report.

The Committee discussed the question of what should be the future actions of the Committee.  In view of the large number of terms already defined, the sense of the meeting was not to consider any new category
of terms for the next year. However, the Committee agreed to meet at the next ASMS meeting to consider further activities.

F.H. Field Chairman
6 June 1984


<big><big><big>'''Combined List of Defined Terms'''</big></big></big>
==Analyzers==

{{ASMS analyzers}}

==Data System==

. . . 

==Ionization Nomenclature ==

;[[Electron ionization]] 
:This is the term used to describe ionization of any species by electrons. The process may, for example, be written
 
::M + e<sup>-</sup> &rarr; M<sup>+&middot;</sup> + 2e<sup>-</sup>. 

for atoms or molecules, .. and M + e<sup>-</sup> &rarr; M+ + 2e<sup>-</sup> for radicals. 
 
;[[Photo-ionization]] 
:This is the term generally used to describe ionization of any species
:by photons. The process may, for example, be written

 
:[Note: Electrons and photons do not "impact" molecules or atoms. They interact with them in ways that result in various electroriic excitations including ionization. For this reason it is recommended that the terms '[[electron impact]]' and '[[photon impact]]' be not used). 

;[[Field ionization]] :This term relates to the removal of electrons from any species by interaction with a high electrical field. 

;[[Field desorption]]
:This term is used to describe the formation of ions in the gas phase from a material deposited ona solid surface (known as an 'emitter') in the presenceof a high electrical field. '[[Field desorption]]' is an ambiguous term because it implies that the electric field desorbs a material as an ion from some kind of emitter on which the materialis deposited. There is growing evidence that some of the ions fanned are due to themal ionization, some to field ionization of vapor evaporated from material on the emitter. Because there is little or no ionization unless the emitter is heated by an electric current, 'field desorption' is a misnomer. The term is however firmly implanted in the literature and most users (by no means all) understand what is going on regardless of the implications of the term. In addition, no better simple term has been suggested to take its place and so; reluctantly, it is recommended that it be retained.

:[[Chemi-ionization]] and [[chemical ionization]] are two terms which should not be used inter-changeably.

;[[Chemi-ionization]]
:refers to a process whereby gaseous molecules are ionized when they interact with other internally excited gaseous molecules or molecular moieties. 

;[[Chemical ionization]] 
:concerns the process whereby new ionized species are formed when gaseous molecules interact with ions. The process may involve transfer of an electron, proton or other charged species to or between the reactants. When a positive ion results from chemical ionization, the term may be used without qualification. When a negative ion results, the term [[negative ion chemical ionization]] should be used. 

;[[Surface ionization]]
:takes place when an atom or molecule is ionized when it interacts with a solid surface. Ionization only.occurs when the work function of the surface, the temperature of the surface, and the ionization energy of the atom or molecule nave an appropriate relationship. 

;[[Thermal ionization]] 
:takes place when an atom or molecule interacts with a heated surface or is in a gaseous environment at high_ temperatures.: [Examples of the latter may be a capillary a_rc plasma, a microwave plasma, or an inductively coupled plasma]. 

;[[Atmospheric pressure ionization]] 
:is an ambiguous term. In essence, it is used to describe chemical ionization at atmospheric pressure. It is recommended that use of the term should be discouraged. 

;[[spark ionization|Spark (source) ionization]] 
:occurs when a solid sample is vaporized and partially ionized by an intermittent electric discharge. Further ionization occurs in the discharge when gaseous atoms and small molecular moieties interact with energetic electrons in the intermittent discharge. It is recommended that the word 'source' be dropped from this term. 

;[[Auto-ionization]] 
:occurs when an internally [[supra excited atom]] or molecular moiety loses an electron spontaneously without further interaction with an energy source. (The state of the atom or molecular moiety is known as a [[pre-ionization state]]). 

;[[Associative ionization]] 
:occurs when two excited gaseous atoms or molecular moieties interact and the sum of their internal energies is sufficient to produce a single, additive ionic product. 

;[[Multi-photon ionization]] 
:occurs when an atom or molecule and their concomitant ions have energy states whereby the energy in two or more photons can be absorbed. 

;[[Penning ionization]] 
:occurs through the interaction of two or more neutral gaseous species at least one of which is internally excited. 

;[[Charge exchange ionization|Charge exchange]] ([[charge transfer|charge transfer ionization]]) ionization 
:occurs when an ion/atom or ion/molecule reaction takes place in which the charge on the ion is transferred to the neutral species without any dissociation of either.
 
;[[Ion-pair formation]] 
:involves an ionization process in which a positive fragment ion and a negative fragment ion are the only products.
 
;[[Ionization cross section]] 
:This is a measure of the probability that a given ionization process will occur when an atom or molecule interacts with an electron or a photon. 

;[[Electron attachment]] 
:A resonance process whereby an external electron is incorporated into an atomic or molecular orbital of an atom or molecule. 

;[[Ionization energy]] 
:This is the minimum energy of excitation of an atom, molecule or molecular moiety required to remove an electron in order to produce a positive ion. 

;[[Vertical ionization]] 
:This is a processs whereby an electron is removed from a molecule in its ground or an excited state so rapidly that a positive ion is produced without change in the positions or momenta of the atoms. The resultant ion is often in an excited state. 

;[[Adiabatic ionization]] 
:A process whereby an electron is removed from the ground state of an atom or molecule producing an ion in its ground state.
 
;[[Ionization]] 
:A process which produces an ion from a neutral atom or molecule. 

;[[Dissociative ionization]] 
:Im ionization process in which a gaseous molecule decomposes to form products, one of which is an ion. 

;[[Ionic dissociation]] 
:A decomposition of an ion into another ion of lower formula-weight and one or more neutral species. 

;[[Ionization efficiency]] :is the ratio of the number of ions formed to the number of electrons or photons used. 

;An [[ionization efficiency curve]] :shows the number of ions produced as a function of the energy of the electrons or photons used to_produce ionization. 

;[[Laser ionization]] 
:occurs when a sample is irradiated with a laser beam. In the irradiation of gaseous samples, ionization occurs via a single-or multi-photon process. In the case of solid samples, ionization occurs via_ a thermal process.

;[[Desorption Ionization]] ([[DI]])
:General term to encompass the various procedures ([[secondary ion mass spectrometry]], [[fast atom bombardment]], [[californium fission fragment desorption]], [[thermal desorption]]) in which ions are generated directly from a solid sample by energy input.

==Types of Ions==

;[[Positive ion]] :This is an atom, radical, molecule or molecular moiety which has lost one or more electrons thereby retaining an electrically positive charge. The use of the term cation as an alternative is not recommended. The use of mass ion is not recommended.

;[[Negative ion]] :An atom, radical, molecule or molecular moiety in the vapor phase which has gained one or more electrons thereby acquiring an electrically negative charge. The use of the term anion as an alternative is not recommended.







==Ion/molecule reactions==


==Sample Introduction ==
{{ASMS sample introduction}}

==Scanning of spectra== 
{{Scanning of spectra}}

==Vacuum==

. . .




[[category:reference]]