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

Abstract

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.

Ion‐induced damage evaluation with Ar cluster ion beams

“…The sputtering rates of the damaged layer were smaller than those of the bulk in both materials. As mentioned earlier, fullerene contained within PCBM transform into DLC by ion bombardment, and diamond is quite difficult to sputter . In the case of PS, cross‐linking between chains occurred with ion bombardment, so irradiated PS sputters with more difficulty than unirradiated PS.…”

“…In previous work, the damage depth on the surface of monomer ion‐irradiated arginine could be accurately evaluated by molecular depth profiling with Ar cluster ion beam . The ion‐induced damage varies according to chemical structure and the damage depth evaluation also depends on the chemical structure.…”