Secondary-ion emission of amino acids

Benninghoven, A.; Jaspers, D.; Sichtermann, W.

doi:10.1007/bf00895013

Cited by 299 publications

(137 citation statements)

References 4 publications

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“…For example, in the case of Arg, the yields of Arg+H + were extremely low compared to those of typical fragment ions when relatively small cluster ions (Ar 300 ) were incident. This result was similar to that observed for amino acids under the incidence of keV-energy Ar + ions [13,14], and similar results were obtained for Leu and PS samples.…”

Section: Methodssupporting

confidence: 90%

SIMS Depth Profiling of Organic Materials with Ar Cluster Ion Beam

Ninomiya

Ichiki

Yamada

et al. 2010

Trans. Mat. Res. Soc. Japan

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Depth profiling has been rarely used with secondary ion mass spectrometry (SIMS) of organic materials, because the primary keV atomic ions produce weak signals for large molecules and often damage them during the etching process. In previous studies, we have found extremely low-damage secondary ion emission from organic materials bombarded with large Ar cluster ions, and proposed to use large gas cluster ions as primary ions for SIMS. In this study, secondary ions were measured with a linear type time-of-flight (TOF) technique, and the application of large Ar cluster ion beams to molecular depth profiling of organic films is demonstrated. The intensities of molecular ions were kept constant, though the primary ion beam fluence exceeded the static SIMS limit. These results indicate that large Ar cluster ion beams could be used as powerful tools for SIMS depth profiling.

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Section: Methodssupporting

confidence: 90%

SIMS Depth Profiling of Organic Materials with Ar Cluster Ion Beam

Ninomiya

Ichiki

Yamada

et al. 2010

Trans. Mat. Res. Soc. Japan

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“…In comparison to Ar bombardment under identical conditions, bombardment with SF 5 gives a 10 to 50 fold enhancement in the secondary ion yields for characteristic molecular ions. The SF 5 primary ion beam can be focussed to a small spot allowing molecular ion images to be obtained at micrometer spatial resolution with enhanced sensitivity.…”

mentioning

confidence: 94%

“…More importantly, the decay in molecular ion signal as a function of primary ion dose commonly observed in SIMS using monoatomic primary ions is either eliminated or greatly reduced, allowing molecular depth profiles to be obtained of organic thin films. By continuing to sample intact molecules as sputtering proceeds into the sample, the total number of detected characteristic secondary ions is increased by as much as a factor of $700 for SF 5 bombardment as compared to Ar bombardment under identical analytical conditions. This effect is thought to be a result of the high erosion rate and the low penetration depth inherent in the use of a polyatomic primary projectile.…”

mentioning

confidence: 98%

Preliminary evaluation of an SF5+ polyatomic primary ion beam for analysis of organic thin films by secondary ion mass spectrometry

Gillen

Roberson

1998

Rapid Commun. Mass Spectrom.

257

229

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Organic vapor deposited thin films of pure biomolecules, polymer films and biomolecules dispersed in gelatin and biological tissue have been analyzed in a magnetic sector secondary ion mass spectrometer using an SF5+ primary ion beam at keV impact energies. In comparison to Ar+ bombardment under identical conditions, bombardment with SF5+ gives a 10 to 50 fold enhancement in the secondary ion yields for characteristic molecular ions. The SF5+ primary ion beam can be focussed to a small spot allowing molecular ion images to be obtained at micrometer spatial resolution with enhanced sensitivity. More importantly, the decay in molecular ion signal as a function of primary ion dose commonly observed in SIMS using monoatomic primary ions is either eliminated or greatly reduced, allowing molecular depth profiles to be obtained of organic thin films. By continuing to sample intact molecules as sputtering proceeds into the sample, the total number of detected characteristic secondary ions is increased by as much as a factor of approximately 700 for SF5+ bombardment as compared to Ar+ bombardment under identical analytical conditions. This effect is thought to be a result of the high erosion rate and the low penetration depth inherent in the use of a polyatomic primary projectile.

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“…This technique was one of the earliest schemes for detecting organic molecules that were not amenable to electron impact ionization, which, at that time, was the only option for this type of analysis (1). The approach has some fundamental flaws, however, and has been eclipsed by MALDI and ESI in recent years.…”

Section: Tof-sims and The Expanding World Of Msmentioning

confidence: 99%