High-speed atomic oxygen irradiation of atomically thin graphene for astronomical applications

Abstract

The first results of high-speed atomic oxygen (AO) irradiation tests for atomically thin single-layer graphene sheets are presented as space environmental tolerance evaluation tests toward application in astronomy. The single-layer graphene sample was prepared without a metal coating, and high-speed AO irradiation tests were conducted with an averaged velocity of ∼6 km∕s using a laser-detonation AO beam source assuming a low Earth orbit (LEO) case. The Raman spectral features were examined before and after the tests with fluence values of 2 × 10 15 , 2 × 10 16 , 2 × 10 17 , 2 × 10 18 , and 2 × 10 19 atoms∕cm 2 . It was found that there is no significant change in the observed D∕G ratios for fluence up to 2 × 10 17 atoms∕cm 2 . In contrast, the D∕G ratios changed from 0.04 AE 0.03 to 0.8 AE 0.4 for 2 × 10 18 atoms∕cm 2 drastically in both the averaged value and 1-sigma range. Furthermore, the D∕G ratio could not be measured beyond 2 × 10 19 atoms∕cm 2 because no peaks were observed in both the G and D bands, which suggests that the degradation occurs between 2 × 10 17 and 2 × 10 18 atoms∕cm 2 and no graphene sheets exist after the 2 × 10 19 atoms∕cm 2 irradiation. Scanning electron microscopy images also support this conclusion in terms of the observed image contrast. Consequently, to protect the single-layer graphene sheets from erosion, a special treatment such as coating is needed to survive in an LEO for ≳ a day.