title: Transmission measurement based on STM observation to detect the penetration depth of low-energy heavy ions in botanic samples.
abstract: The penetration depth of low-energy heavy ions in botanic samples was detected with a new transmission measurement. In the measurement, highly oriented pyrolytic graphite (HOPG) pieces were placed behind the botanic samples with certain thickness. During the irradiation of heavy ions with energy of tens of keV, the energetic particles transmitted from those samples were received by the HOPG pieces. After irradiation, scanning tunneling microscope (STM) was applied to observe protrusion-like damage induced by these transmitted ions on the surface of the HOPG. The statistical average number density of protrusions and the minimum transmission rate of the low-energy heavy ions can be obtained. The detection efficiency of the new method for low-energy heavy ions was about 0.1-1 and the background in the measurement can be reduced to as low as 1.0 x 10(8) protrusions/cm2. With this method, the penetration depth of the energetic particles was detected to be no less than 60 micrometers in kidney bean slices when the slices were irradiated by 100 keVAr+ ion at the fluence of 5 x 10(16) ions/cm2.
authors.affiliation: Ion Beam Group, Institute of Heavy Ion Physics, Peking University, Beijing, People's Republic of China.
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.forename: Yugang
authors.initials: Y
authors.lastname: Wang
authors.forename: Jianming
authors.initials: J
authors.lastname: Xue
authors.forename: Sixue
authors.initials: S
authors.lastname: Wang
authors.forename: Guanhua
authors.initials: G
authors.lastname: Du
authors.forename: Weijiang
authors.initials: W
authors.lastname: Zhao
mesh_terms: D001128:Argon; D004249:DNA Damage; D004260:DNA Repair; D017343:Genes, Plant / Q000528:radiation effects; D006108:Graphite; D020450:Heavy Ions; D016252:Microscopy, Scanning Tunneling; D008962:Models, Theoretical; D009154:Mutation; D027805:Phaseolus / Q000235:genetics / Q000528:radiation effects*; D011829:Radiation Dosage; D011834:Radiation Monitoring / Q000295:instrumentation / Q000379:methods*
chemical_list: D001128:Argon; D006108:Graphite