bluuebunny/crossref_metadata_2025_split huggingface dataset:
Collisional activation spectra of quarternary ammonium cations produced by field desorption
Authors: Gierlich H. H. , Röllgen F. W. , Borchers F. , Levsen K. 
Published: May 2005

AbstractCollisional activation spectra of quarternary ammonium cations produced by field desorption are reported. The principal fragmentation pathways of these ions are discussed. Furthermore, it is demonstrated that collisional activation in conjunction with field desorption is useful for the elucidation of the structure of complex organic cations.
Massenspektrometrische Untersuchung organischer Stickstoffverbindungen. XXVII—Intramolekulare Redoxreaktionn bei ionisierten ortho‐substituierten Nitroaromaten
Authors: Schwarz Helmut , Sezi Recai , Levsen Karsten , Heimbach Heinz , Borchers Friedrich 
Published: May 2005

AbstractMit Hilfe der Stoßaktivierungsspektroskopie wird belegt, daß die stabilen magnified image‐Ionen aus o‐Nitrobenzaldehyddimethylacetal als ionisierte o‐Nitrosobenzoesäuremethyleser vorliegen. Ferner wird—im teilweisen Gegensatz zu den Resultaten älterer Arbeiten—belegt, daß die durch elektronenstoßin duzierte H2O‐Eliminierung aus o‐Nitrobenzylalkohol, HCN‐Abspaltung aus o‐Nitrobenzylcyanid order HNO‐Verlust aus o‐Nitrobenzaldoxim erzeugten magnified image‐Ionen praktisch vollständig die Struktur von 2.1‐Benzisoxazolin‐3‐on besitzen. Ionisierter o‐Nitrosobenzaldehyd lagert sich vor dem stoßinduzierten Zerfall vollständig in 2.1‐Benzisoxazolin‐3‐on um, während 2‐Benzoxazolinon und 3‐Hydroxy‐1.2‐benzisoxazol innerhald von 10−5s weitgehend strukturstabil sind.
Stereochemistries of electron impact induced hydrogen abstraction reactions proceeding through 6‐membered transition states
Authors: Eadon George 
Published: May 2005

AbstractThe stereochemistries of nine electron‐impact induced eliminations proceeding from derivatives of thecis‐4‐t‐butyl system have been determined. The predominantciselimination observed in every case is consistent with the substantial integrity of the cyclohexyl ring prior to fragmentation, and with a cyclic transition state for hydrogen abstraction. The stereochemistries of electron impact induced eliminations from 11 derivatives of thetrans‐4‐t‐butylcyclohexyl system exhibit a dichotomy. The predominatntransstereochemistry observed in six electron impact induced eliminations, and the nonstereospecific electron impact induced dehydration oftrans‐4′‐t‐butylcyclohexyl‐ethanol are consistent with nonconcerted elimination from a chair‐like cyclohexyl ring. Conversely, the McLafferty rearrangement oftrans‐4′‐t‐butyl‐cyclohexyl‐2‐propanone proceeds nonstereospecifically.trans‐4‐t‐Butylcyclohexyl acetaldehyde, 2‐methyl‐3‐(trans‐4′‐t‐butylcyclohexyl)‐1‐propane andtrans‐4‐t‐butylcyclohexyl‐S‐methyl xanthate exhibit predominantcisMcLafferty rearrangement stereochemistry. This result may be due to fragmentation through boat‐like conformers in these compounds.
Ionisation et Fragmentation en Spectrométrie de Masse. VI—Energie d'Activation de la Fragmentation Principale des Monohalogénobenzènes
Authors: Bouchoux Guy 
Published: May 2005

AbstractL'énergie d'activation de la fragmentation principale des monohalogénobenzènes [C6H5X⋅]+ → [C6H5]+ + X⋅ (X = Cl, Br, I) est calculée par diverses méthodes. L'analyse des ions métastables indique l'absence d'une énergie de recombinaison des fragments appréciable. Ces résultats sont comparés aux données expérimentales.
Der Zerfall von Substituierten p‐ Toluesäuren—eine neuartige Skelettumlagerung
Authors: Budzikiewicz H. , Scheipers R. , Rullkötter J. 
Published: May 2005

Abstractp‐Carboxy‐ und p‐Carbomethoxybenzylionen zerfallen unter CO‐Eliminierung zu p‐Hydroxy‐ bzw. p‐Methoxybenzylionen.
On the formation of artefact peaks in linked scans of the magnet and electric sector fields in a mass spectrometer
Authors: Morgan R. P. , Porter C. J. , Beynon J. H. 
Published: May 2005

AbstractThe apperrance of peaks at non‐integral masses in linked scans, where the ratio B/E is kept constant, is shown to be caused by fragmentations of metastable ions occuring in the region between the magnetic and electric sectors. A formula is given for calculating the mass of the parent metastable ion and that of its daughter ion.
Studies in negative ion mass spectrometry. VIII—Electron capture by some monomeric and dimeric η5—cylcopentadienyl transition metal carbonyls
Authors: Blake M. R. , Garnett J. L. , Gregor I. K. , Wild S. B. 
Published: May 2005

AbstractThe negative ion mass spectra of a series of monomeric and dimeric η5‐cyclopentadienyl transition metal carbonyls have been examined. The base peak in the case of the monomeric compounds (η5‐C5H5)V(CO)4, (η5‐C5H5)Mn(CO)3 and (η5‐CH3C5H4)Mn(CO)3 arises from a reductive decarbonylation of the parent molecule—the resulting radical anion [M–CO]− is formally isoelectronic with the molecular cations [M]− observed in the positive ion mass spectra of these compounds and subsequently undergoes successive decarbonylations to the ‘aromatic’ cyclopentadienyl anions. For the compound (η5‐C5H5)Co(CO)2, however, a molecular anion was observed as the base peak which has been formulated as [(η3‐C5H5)Co(CO)2]− in the light of considerations based on the rare gas rule. As expected, the dimeric molecules [(η5‐C5H5)M(CO)3]2 (where M = Cr or Mo) and [(η5‐C5H5)Fe(CO)2]2 (and its methyl analogue) undergo reductive cleavage of their metal‐metal bonds to give the anions [(η5‐C5H5)M(CO)3]− and [(η5‐C5H5)Fe(CO)2]− as the base peaks in their negative ion mass spectra. The dimeric nickel compound [(η5‐C5H5)Ni(CO)]2, however, reductively decarbonylates to the [M‐CO]− radical anion as its predominant fragmentation in the gas phase. Very low abundances of [(η5‐C5H5)Fe(CO)2] and [(η5‐CH3C5H4)Fe(CO)2] were also observed.
Electron impact studies. CXX—The properties of positive ions produced by charge stripping from negative ions. The acetate and perfluoroacetate cations
Authors: Bowie John H. , Benbow John A. 
Published: May 2005

AbstractThe ions [CF3CO2]+ and [CH3CO2]+ give peaks of small abundance in conventional positive ion spectra. These ions can be produced by collision‐induced charge stripping of the corresponding stable negative ions. Six and ten fragment ions respectively are observed in the spectra of [CF3CO2]+ and [CH3CO2]+.
On the apparent ketonization of the [MC2H4]+ ion from o‐hydroxybutyrophenone
Authors: Molenaar‐Langeveld T. A. , Nibbering N. M. M. , Morgan R. P. , Beynon J. H. 
Published: May 2005

AbstractDeuterium labelling and kinetic energy release measurements have shown that the initially enolic [MC2H4]+ ions from o‐hydroxybutyrophenone have rearranged to o‐hydroxyacetophenone ions, if they eliminate a methyl radical.
Etude en Spectrométrie de Masse. X—Fragmentation d'Ethanes Disubstitués par un Hétéroatome des Colonnes IV, V et VI, et par un Groupement Fonctionnel
Authors: Greiner Jacques , Rouvier Emile , Cambon Aimé 
Published: May 2005

AbstractNous comparons et discutons dans ce travail les résultats obtenus lors de la fragmentation d'éthers, sulfures, sélénoéthers, amines, germanes et stannanes fonctionalisés en β par un groupement méthoxycarbonyle, méthylcétone ou nitrile. Les divers composés possédant un élément de la colonne VB et VIB du tableau périodique sont relativement stables sous l'impact électronique, alors que ceux de la colonne IVB se fragmentent très facilement. Les ruptures en α de l'hétéroatome donnent des pics dont l'intensité augmente avec la taille de celui‐ci: [PhO]+<[PhS]+<[PhSe]+<[Ph3Ge]+<[Ph3Sn]+. La rupture en β conduit à des fragments d'autant plus intenses que le groupement fonctionnel a un potentiel d'ionisation plus faible ou un effet inductif plus fort (CN<CO2CH3<COCH3).
Dissociations Induites par Collisions d'Ions Générés par Echange de Charges
Authors: Maquestiau A. , Van Haverbeke Y. , De Meyer C. , Flammang R. 
Published: May 2005

AbstractLes dissociations induites par collisions d'ions moléculaires créés par impact d'électrons et par échange de charges dans une source d'ionisation chimique (méthane) sont comparés.
A quality index for reference mass spectra
Authors: Speck David D. , Venkataraghavan Rengachari , McLafferty Fred W. 
Published: May 2005

AbstractA numerical rating for evaluating the quality of reference mass spectra used for retrieval and interpretive applications is proposed. The overall quality index is the product of seven quality factors: (1) source of the spectrum; (2) ionization conditions; (3) higher molecular weight impurities; (4) illogical neutral losses; (5) isotopic abundance accuracy; (6) number of peaks; and (7) lower mass limit of peaks. For quality factor 6 the number of peaks of abundances ≥1% was found to correspond to 15 more than the number of atoms in the molecule with a correlation coefficient of 0.482. The program has been found useful in preparing a data base of 41429 mass spectra; for the majority of spectra judged to be unsatisfactory by the program this arose from a low quality factor 6 value (too few peaks).
The mass spectra of 1,2,5‐triazapentadienium salts
Authors: McNab Hamish 
Published: May 2005

AbstractThe mass spectra of some 1,2,5‐triazapentadienium salts are described. The major breakdown pathways involve loss of Ph· from the 1‐position of the azo form, and of PhNH· from the hydrazone tautomer of the conjugate base.
Mass spectra of some oxadiazole derivatives
Authors: Nakano Tatsuhiko , Márquez Víctor E. , Di Parsia María T. , Suárez Cecilia 
Published: May 2005

AbstractThe mass spectra of some substituted oxadiazoles have been determined and analysed with the aid of high resolution mass spectrometry. Some characteristic and major differences between their spectra have been noted, and possible rationalizations have been advanced. The main fragmentation patterns of the 1,3,4‐oxadiazole derivatives have been interpreted in terms of diazirine intermediates. Specific skeletal rearrangement processes have been observed in the spectra of the 1,3,4‐ and 1,2,4‐oxadiazoles, and possible mechanisms are proposed.
Characterization by three‐dimensional representation of sequential transitions of metastable ions in a double focusing mass spectrometer
Authors: Lacey M. J. , Macdonald C. G. 
Published: May 2005

AbstractThe ion currents due to products of selected ion reactions of toluene and 3‐chlorophenol, occurring in the source or flight tube of a double focusing mass spectrometer for which the electric sector precedes the magnetic sector, have been represented by plotting them against two variables that reflect independently the effects of the sectors. The daughter ion produced from the molecular ion of 3‐chlorophenol that decays by sequential losses of CO in the field free region preceding the electric sector and Cl˙ in the field free region preceding the magnetic sector gives rise to a peak with a distinctive shape on the resultant three‐dimensional surface. A peak due to the daughter ion arising from the corresponding sequential losses of H˙ and C2H2 from the molecular ion of toluene could not be detected. A portion of the ion kinetic energy spectrum which would be recorded by a detector at the energy resolving slit is derived from the surface for 3‐chlorophenol and is in satisfactory agreement with a published spectrum.
Mass spectra of germacranolide type sesquiterpene dilactones and derivatives
Authors: Perry Donald L. , Desiderio Dominic M. , Fischer Nikolaus H. 
Published: May 2005

AbstractThe low and high resolution mass spectra of five germacranolide sesquiterpene dilactones together with the d0‐, d3‐acetates, d0‐, d9‐TMSi derivatives and deuterium exchange products were obtained. The mass spectra of the five dilactones revealed several kinds of common fragment ions. The germacranolides containing a 4,5 double bond exhibit characteristic ions at m/e 274, 256, 228, 165 and 147, while the 4,5‐dihydro compound exhibits fragment ions at m/e 276, 258, 230 and 162.
A mass spectrometric investigation of the reduction product of 3H‐1,2‐benzodithiole‐3‐thione
Authors: Parfitt Robert T. , Games David E. , Cookson Ronald F. , Richards Alan C. , Lynaugh Norman 
Published: May 2005

AbstractA combination of electron impact, chemical ionization, field desorption and field ionization mass spectrometry has been employed to demonstrate that the LAH reduction product of 3H‐1,2‐benzodithiole‐3‐thione is the dimer, dibenzo[c,h]‐3H,10H‐dihydro‐1,2,8,9‐tetrathiecine.
Laser assisted field desorption mass spectrometry
Authors: Schulten H.‐R. , Lehmann W. D. , Haaks D. 
Published: May 2005

AbstractThe method of indirectly heating the emitter wire with a laser is introduced into field desorption mass spectrometry. Use of this method results in improved sensitivity, more reliable high resolution performance, and extension of field desorption mass spectrometry to the area of high temperature chemistry.
Ionen‐Cyclotron‐Resonanzuntersuchungen an Ionen–Molekül‐Komplexen von Anisol und Anisolhomologen
Authors: Szabo A. , Suhr H. , Miller L. L. 
Published: May 2005

AbstractDie ICR‐Spektren von Anisol, 3‐Methylanisol, Phenetol, 3‐Methylphenetol und Thioanisol, die bei 10−6Torr weitgehend mit den normalen Massenspektren übereinstimmen, zeigen oberhalb von 10−5Torr zahlreiche Signale von Produktionen. Doppelresonanzmessungen ergaben, daß die meisten Produktionen durch Reaktion eines Fragmentions mit einem Äthermolekül unter Abspaltung eines Alkyl‐, Alkoxy‐ oder Thioalkylradikals bzw. von Äthylen entstanden sind. Daneben finden sich einzelene Produktionen (möglicher‐weise Ion‐Molekül‐Komplexe), die durch Zusammentreten von Ionen mit Äthermolekülen ohne Eliminierung entstanden sind. Radikalionen, mit Ausnahme des Molekular ions, nehmen nicht an den Ionen‐Molekül‐Reaktionen teil.
Zur Lokalisierung funktioneller Gruppen mit Hilfe der Massenspektrometrie. XVII—Massenspektren von 3,6,20β‐Trihydroxy‐pregnanen
Authors: Grupe Albrecht , Spiteller Gerhard 
Published: May 2005

AbstractDie Massenspektren von 3,6,20β‐Trihydroxy‐pregnanen unterscheiden sich je nach Stellung der Hydroxy‐gruppen und der Ringverknüpfung teilweise beträchtlich voneinander. So wird von allen Isomeren nur das 3α,6β,20β‐Trihydroxy‐5β‐pregnan unter Bildung eines intensiven Schlüsselions der Masse 263 gespalten. Für das 3β,6α,20β‐Trihydroxy‐5α‐pregnan ist die Bildung eines Schlüsselions der Masse 141 charakteristisch.
Beiträge zum Studium einiger Heterocyclen. L—Massenspektrometrische Untersuchungen von 2‐Aryl‐4‐r‐5‐acetylthiazolen
Authors: Demian H. , Coman Mioara , Muresan Ana , Iovanov I. , Simiti I. 
Published: May 2005

AbstractEs werden die Massenspektren von 5‐Acetylthiazolen untersucht und Unterschiede im Vergleich zu den in einer vorhergegangenen Arbeit veröffentlichten Spektren von entsprechenden 4‐Acetylderivaten, auf Grund deren man beide Verbindungsgruppen indentifizieren könnte, aufgezeigt. Die Natur der Substituenten vom C‐4 beeinflusst das Fragmentierungsschema des Thiazolringes. Bei 4‐Hydroxymethylderivaten findet eine Skelettneuanordnung vor der Fragmentierung statt.
Studies in negative ion mass spectrometry. IX—electron capture by a series of tris‐ and bis‐(dipivaloylmethanato) metal chelates
Authors: Garnett J. L. , Gregor I. K. , Guilhaus M. 
Published: May 2005

AbstractElectron capture data and negative ion mass spectra are reported for a series of tris‐ and bis‐chelates of the types Metal·L3, Metal·L2, where L (or dpm) refers to the ligand or enolate ion of the β‐diketone 2,2,6,6‐tetramethyl‐3,5‐heptanedione (dipivaloylmethane) and the metals are: Sc(III), Cr(III), Mn(III), Fe(III), Co(III), Al(III), Ga(III), In(III), Co(II), Ni(II), Cu(II), Zn(II). The spectra were all very simple and the principal ions observed in all cases were the molecular anions and ligand ions. Reaction schemes have been established to account for the formation of ligand and other fragment ions, many of which carried less than 0.1% of the total ion currents. Variations in the negative ion mass spectra are attributed to the influence of the metal atom and its 3d electron configuration on the electron capture process. The simplicity of the negative ion mass spectra, together with the fact that many of these metal chelates gave relatively high total ion currents of c. 10−9–10−10 A, indicates the potential value of negative ion mass spectrometry in the area of ultra‐trace metal analysis, and some estimates of detection limits for some of the metals considered in this study have been made.
On the CO elimination from [M – CH3]+ ions in substituted phenyl methyl ethers
Authors: Florêncio Helena , Heerma Wigger , Vijfhuizen Peter C. 
Published: May 2005

AbstractIt was inferred from the collisional activation spectra that CO loss from [M – CH3]+ ions generated from o‐,m‐ and p‐cyanoanisole yields a common ion, presumably the cyanocyclopentadienyl cation. A similar product ion is found to be generated in the three dimethoxybenzene isomers. In case of o‐dimethoxybenzene loss of CO was also found to occur via an important additional route, which leads to the formation of protonated phenol.
Mass spectrometry of π‐complexes of transition metals. XIII—The dehydration process and genesis of ions [M–O]+⋅ in the mass spectra of cymantrenyl‐, ferrocenyl‐and benchrotrenylcarbinols
Authors: Nekrasov Yu. S. , Sizoi V. F. , Zagorevskii D. V. , Vasyukova N. I. 
Published: May 2005

AbstractThe mass spectra of a number of cymantrenyl‐, ferrocenyl‐ and benchrotrenylcarbinols have been studied. The elimination of water molecules from the molecular ions proceeds by the 1,2‐elimination mechanism involving hydroxyl transfer to the metal. The [M–16]+ ions originate from thermal decomposition of the compounds studied in the inlet system.
Skeletal rearrangements of protonated molecular ions of some ethers
Authors: Diakiw Vladimir , Shannon James S. , Lacey Michael J. , MacDonald Colin G. 
Published: May 2005

AbstractSkeletal rearrangements are reported of protonated molecular ions in the chemical ionization mass spectra of allyl cyclohexyl ether, benzyl cyclohexyl ether, t‐butyl cyclohexyl ether and dibenzyl ether.
The activation energy of the skeletal isomerization in the radical cations of toluene and cycloheptatriene by mass spectrometry of their 2‐phenylethyl derivatives
Authors: Kuck Dietmar , Grützmacher Hans‐Fr. 
Published: May 2005

AbstractThe Unimolecular mass spectrometric fragmentations of the molecular ions of 1,3‐diphenylpropane, 1‐(7‐cycloheptatrienyl)‐2‐phenylethane and the 1‐phenyl‐2‐tolylethanes and their [d5]phenyl analogues have been investigated by metastable ion techniques and measurements of ionization and appearance energies. By comparing the formation of [C7H7]+, [C7H8]+⋅, [C8H8]+⋅ and [C8H9]+ it is shown that the molecular ions of the four diaryl isomers do not undergo ring expansion reactions of the aromatic nuclei prior to these fragmentations. Conversely, the molecular ions of the cycloheptatrienyl isomer suffer in part a contraction of the 7‐membered ring. From these results and from the measured ionization and appearance energies lower limits to the activation energies of these skeletal isomerizations have been estimated yielding E > 33±5 kcal mol−1 formonoalkylbenzene, E > 20 2±5 kc mol−1 for 7‐alkylcycloheptatriene and E > 40±5 kcal mol−1 for dialkylvbenzene positive radical ions. Upper limits can be deduced from literature evidence yielding E < 45 kcal mol−1 for monoalkylbenzene and E < 53 kcal 4mol−1 for dialkylbenzene positive radical ions. The activation energy thus estimated for monoalkylbenzene is in excellent agreement with the recently calculated value(s) for the toluene ion.
Electron impact induced fragmentations of 2‐(2‐nitroanilino)thiophens and Di(2‐nitrophenyl)sulphides
Authors: Mallen David N. B. , Smith Julie M. 
Published: May 2005

AbstractA prominentorthointeraction occurs during the mass spectral fragmentation of di(2‐nitrophenyl)sulphides. No such effects are observed for the corresponding ethers or 2‐(2‐nitroanilino)thiophens. Variation of aromatic substituents can dramatically alter the effect. Examination of analogous sulphone, sulphoxide, and disulphide molecules, implicates the involvement of theorthonitro substituent and the sulphur atom in this rearrangement.
Distinction between glycosylamines and amadori products by mass spectrometry of their trimethylsilyl derivatives
Authors: Funcke Werner , Henneberg Dieter , Von Sonntag Clemens , Klemer Almuth 
Published: May 2005

AbstractThe TMS‐ethers of four glycosylamines and seven Amadori compounds have been investigated by electron impact mass spectrometry. The mass spectra of glycosylamine‐TMS derivatives and of their isomeric Amadori rearrangement products are quite characteristic. The two types of compounds can be distinguished by a few characteristic peaks.
Massenspektrometrie kondensierter N‐Heterocyclen. 1–Elektronenstoßinduzierte Bildung von Cyclaziniumionen aus 5‐Aryl(Hetaryl)‐9‐methyl‐s‐triazolo[4,3‐c]tetrazolo‐[1,5‐a]pyrimidinen
Authors: Könnecke Anderas , Lepom Peter , Dörre Ronald , Lippmann Eberhard 
Published: May 2005

AbstractDie Elektronenstoß‐Massenspektren von 5‐aryl(hetaryl)‐9‐methyl‐s‐triazolo[4,3‐c]tetrazolo[1,5‐ a]‐pyrimidinen wurden untersucht. Die Fragmentierung gehorcht einem allegmeinen Mechanismus und durch Cyclisierung werden stabile Cyclaziniumionen gebildet. Bei 5‐Hetarylderivaten konnte die postulierte Struktur durch Vergleich der MIKE‐Spektren mit geeigneten Modellverbindungen gesichert werden.
Struktur des [C3H5]+‐Ions im Cl(CH4)‐Plasma
Authors: Wesdemiotis Chrysostomos , Wolfschütz Roland , Höhne Gerhard , Schwarz Helmut 
Published: May 2005

AbstractDie Analyse von CA‐Spektren belegt, daß dem im Methan‐Plasma (Chemische Ionisation) vorliegenden [C3H5]+ Ion die Struktur enies Allylkations zukommt.
The m/z 91 rearrangement ion in the mass spectra of some 1,4‐benzodiazepines
Authors: Vane Floie M. , Benz Wolfgang 
Published: May 2005

AbstractWith the aid of isotope labeling and by substituent shifts, the relatively strong m/z 91 ion in the mass spectra of 7‐chloro‐2‐methoxy‐5‐phenyl‐3H‐1,4‐benzodiazepine and related compounds was shown to contain the 5‐phenyl ring and the 3‐CH2 group. Mechanisms involving the opening of the 7‐membered ring and the migration of the phenyl ring from C‐5 to C‐3 are postulated for the formation of this ion. This rearrangement ion was also observed in the mass spectra of some 1‐alkyl‐7‐chloro‐1,3‐dhydro‐5‐phenyl‐2H‐1,4‐benzodiazepin‐2‐ones.
The fragmentation of doubly charged ions of halogenated benzenes
Authors: Medved Miran , Kralj Bogdan , Marsel Jože , Kramer V. , Ast Teodor , Beynon John H. 
Published: May 2005

AbstractThe unimolecular charge separation fragmentations of doubly charged benzene and 18 derivatives containing various numbers of fluorine, chlorine and bromine atoms have been studied. In the majority of cases two distinct kinds of transition state can be characterized, in one of which the ring system remains intact and in the other of which a linear transition state ion is formed. There is evidence for rearrangement of halogens both around the ring and along the linear chain.
Interference peaks in mass analysed ion kinetic energy spectra
Authors: Ast T. , Bozorgzadeh M. H. , Wiebers J. L. , Beynon J. H. , Brenton A. G. 
Published: May 2005

AbstractWhen mass analysed ion kinetic energy spectroscopy is performed on ions of low abundance and low mass compared with the rest of the ions present in the ion chamber, severe interference may be observed. The major form taken by the interference is of narrow peaks at non‐integral mass numbers. Many such peaks can be observed in mass analysed ion kinetic energy spectra and they are mainly attributed to decompositions of metastable ions occurring in the first field free region of the reversed geometry double focusing mass spectrometer.
Electron impact and chemical ionization mass spectra of aryl ureas
Authors: Brophy Joseph J. , Nelson Derek , Shannon James S. , Middleton Sydney 
Published: May 2005

AbstractThe electron impact and chemical ionization mass spectra of a series of N,N′, ‐diaryl ureas have been compared. The electron impact mass spectra indicate rearrangements leading to two pairs of aromatic amines and isocyanates, either as ions or molecules. The chemical ionization mass spectra showed the formation of protonated amines and isocyanates via rearrangement.