Design features of a high‐intensity, cesium‐sputter/plasma‐sputter negative ion sourcea)

1994 ◽  
Vol 65 (6) ◽  
pp. 2006-2011 ◽  
Author(s):  
G. D. Alton ◽  
G. D. Mills ◽  
J. Dellwo
Keyword(s):  
High Intensity ◽  
Negative Ion ◽  
Design Features

The properties of high‐intensity heavy‐negative‐ion source, NIABNIS

1990 ◽  
Vol 61 (1) ◽  
pp. 427-429 ◽  
Author(s):  
Hiroshi Tsuji ◽  
Junzo Ishikawa ◽  
Takeshi Maekawa ◽  
Toshinori Takagi
Keyword(s):  
High Intensity ◽  
Ion Source ◽  
Negative Ion

Fast Atom Bombardment Mass Spectra of Some N-α-(t-Butoxycarbonyl)-O-(diorganylphosphono)-L-serines and O-(Diorganylphosphono)seryl-Containing Dipeptides and Tripeptides

1994 ◽  
Vol 47 (2) ◽  
pp. 229 ◽  
Author(s):  
JW Perich ◽  
I Liepa ◽  
AL Chaffee ◽  
RB Johns
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrum ◽  
High Intensity ◽  
Mass Spectra ◽  
Fast Atom Bombardment ◽  
Molecular Ions ◽  
Operating Conditions ◽  
Negative Ion ◽  
The Matrix ◽  
Positive Ion

Positive and negative ion fast atom bombardment ( f.a.b .) mass spectrometry were found to be useful methods for the analysis and structural characterization of five Nα-(t- butoxycarbonyl )-O-( diorganylphosphono )-L- serines ( organyl = Ph, Et, Me, Bzl , But), especially in the case of the sensitive benzyl and t-butyl phosphono derivatives. Under positive ion operating conditions, high intensity pseudo-molecular ions were obtained in the f.a.b . mass spectra, and the fragmentation pathway of the phenyl, ethyl and methyl derivatives was established by parent/daughter linked scanning studies to involve (a) the two-step loss of the t- butoxycarbonyl group, (b) loss of the amino acid as the neutral fragment from the [MH]+, [MH-56]+, [MH-100]+ and [MH-146]+ ions by a four- centred β-elimination rearrangement, and (c) cleavage of the phosphono phenyl and ethyl groups from only the [(RO)2P(OH)2]+ and [NH=CHCH2PO3R2+H]+ fragments. Parent/daughter linked scanning studies of the benzyl derivative showed that the prominent fragmentation involved loss of the benzyl group as the tropylium ion and that the 'apparent' [MH-90]+ peak observed in its f.a.b. mass spectrum resulted from cleavage of the phosphono benzyl group in the matrix during the bombardment process. In the case of the t-butyl derivative, parent/daughter linked scanning studies showed that the prominent fragmentation involved successive 'in-flight' loss of the phosphono t-butyl groups as isobutene. Negative ion f.a.b. mass spectrometry of the five derivatives gave f.a.b. mass spectra which displayed distinct [M-H]- anions along with high intensity [M-H-R]- and [(RO)2PO2]- fragment anions, the f.a.b . mass spectrum of the t-butyl derivative containing an additional [M-H-But-But]- fragment anion. Parent/daughter linked scanning studies established that the majority of the observed fragment anions resulted from extensive fragmentation of the Boc -Ser(PO3R2)-OH derivatives in the matrix phase followed by sputtering of the resultant fragments into the gas phase. In addition, positive ion f.a.b . mass spectrometry was found to be useful for the analysis of a series of protected O-( diorganylphosphono ) seryl-containing dipeptides and tripeptides ( organyl = Ph, Et, Me, Bzl ). The obtained spectra showed that β-elimination fragmentation of the Ser(PO3R2) residue was more pronounced with the tripeptide series and indicated that there was increased sensitivity of the O-( diorganylphosphono ) seryl residue with replacement of the Boc group by an amino acyl residue at its N-terminus.

A compact multi-sample high-intensity negative ion source

1997 ◽  
Vol 123 (1-4) ◽  
pp. 550-553 ◽  
Author(s):  
W.Z. Gelbart ◽  
R.R. Johnson ◽  
M. Paul ◽  
D. Berkovits ◽  
A. Hershkowitz ◽  
...  
Keyword(s):  
High Intensity ◽  
Ion Source ◽  
Negative Ion

scholarly journals High-intensity negative ion sources

1963 ◽  
Vol 22 ◽  
pp. 87-92 ◽  
Author(s):  
K.W. Ehlers ◽  
B.F. Gavin ◽  
E.L. Hubbard
Keyword(s):  
High Intensity ◽  
Ion Sources ◽  
Negative Ion
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