Generation of the large current cluster ion beam

Surface & Interface Analysis

Matsuo

2012

The emission of positive secondary ions from four amino acids (arginine, glycine, phenylalanine, and tyrosine) and from NaCl under irradiation with large Arn+ cluster ions was investigated by time‐of‐flight secondary ion mass spectrometry. Size‐selected 5.5‐keV Arn+ cluster ions with 300 ≤ n ≤ 2000 were used, and the flux of sputtered positive ions was monitored as function of cluster size n. For all cluster sizes, the protonated or the cationized molecular ions are observed in the mass spectra. In addition, the results show that with increasing cluster size, the number of fragment molecules strongly decreases in relation to the intact molecules, to the extent that the ratio of fragment to intact ions is 10% or less for the largest cluster ions. Generally, the ion yields Y+ were found to decrease for decreasing impact energy per cluster atom, E/n, and this attenuation was recorded down to values as low as E/n ~ 3 eV/atom. The general trend of Y+ versus E/n is similar for all targets and appears to follow a power‐law dependence, Y+ ∝ (E/n)x, with x ~ 4. This pronounced yield change could be ascribed to a reduction of the ionization probability which is envisaged to depend on the presence of free protons. Their number is expected to decrease concurrently with the decreasing amount of fragmentation for large cluster ions (i.e. for low energies/atom). Copyright © 2012 John Wiley & Sons, Ltd.

Section: Methodsmentioning

confidence: 99%

Sputtered ion emission under size‐selected Ar_n⁺ cluster ion bombardment

Gnaser

Surface & Interface Analysis

Matsuo

2012

“…The large Ar cluster ions were produced by a gas cluster ion beam (GCIB) apparatus. The GCIB technique and equipment are described in detail in refs [19,20], and the source for SIMS is described in ref. [11].…”

Section: Methodsmentioning

confidence: 99%

Evaluation of damage depth on arginine films with molecular depth profiling by Ar cluster ion beam

Yamamoto

Trans. Mat. Res. Soc. Japan

Seki

et al. 2011

Ioninduced damage on organic materials has been evaluated with secondary ion mass spectrometry (SIMS). However, conventional sputter beams, such as SF 5 + , C 60 + cannot etch the organic materials without inducing damage, and it is difficult to evaluate the depth distribution of the damage in these materials. Large gas cluster ion can etch organic materials without damage, and in this study the damaged layer thickness was evaluated by molecular depth profiling with Ar cluster ion beam. Arginine films were irradiated with 10 keV Ga + at a dose of 1.0 × 10 14 ions/cm 2 with the aim of forming a damaged layer on the surface. The chemical structure of arginine was seriously damaged, as indicated by the nondetection of protonated arginine molecular ions after Ga + ions irradiation. The peak intensity of the protonated arginine ion increased with increasing sputtering depth and saturated at the depth of about 30 nm. This value agreed with the projection range of the Ga + ion indicating that the depth of the ioninduced damage was the same as projection range of the ion. Ioninduced damage layer thickness on arginine films were accurately evaluated by molecular depth profiling with Ar cluster ion beam.

“…A method for generating large gas cluster ion beams was developed at Kyoto University. The experimental details of the gas cluster ion formation and ionization techniques were described elsewhere [9][10][11]. Neutral clusters are ionized with electrons ejected from a hot filament and accelerated toward the target samples with a voltage of up to 10 kV.…”

Section: Methodsmentioning

confidence: 99%

Processing Techniques of Biomaterials Using Ar Cluster Ion Beam for Imaging Mass Spectrometry

Yamada

Trans. Mat. Res. Soc. Japan

Nakata

et al. 2010

We investigated secondary ion mass spectrometry (SIMS) for cellular imaging with high spatial resolution. Cellular level imaging would require nanoscale processing techniques for removal of contamination from cell surfaces and exposing the inner matter of cells. In this study, we applied gas cluster ion beams to the etching of biological samples. Molecular ions were detected with high-intensity from cholesterol samples etched with Ar cluster ions. Additionally, the intensity of secondary molecular ions with gas cluster ion irradiation was compared to that with Au 3 + or C 60 + beam irradiation and we demonstrated the advantage of using gas cluster ions as etching beams for biological samples with low damage. Finally, we performed etching of animal cells with Ar cluster ions and SIMS analysis of the etched cells. We demonstrated that the cell surfaces were etched with low damage by using gas cluster ion beam.