Abstract: The present invention discloses a photo-induced DNA-cleaving agent composition comprises N-aryl-N-(alkyl or arylalkyl)hydroxylamine having the following formula: ##STR1## wherein R is C.sub.1 -C.sub.6 alkyl, phenyl, C.sub.1 -C.sub.6 alkoxy, phenoxy, C.sub.1 -C.sub.6 alkoxycarbonyl, halogen or halo(C.sub.1 -C.sub.6 alkyl)wherein R.sub.1 is hydrogen, C.sub.1 -C.sub.6 alkyl, phenyl, C.sub.1 -C.sub.6 alkoxy, C.sub.1 -C.sub.6 alkoxycarbonyl, halogen or halo(C.sub.1 -C.sub.6 alkyl); R.sub.2 is hydrogen; R.sub.3 is hydrogen or phenyl; R.sub.4 is hydrogen, phenyl, hydroxylphenyl, methoxyphenyl, dimethoxyphenyl, dimethylaminophenyl or naphthyl. The present N-aryl-N-(alkyl or arylalkyl)hydroxylamine is stable in dark, but it can react with O.sub.2 to form HO. radicals under irradiation of UV light for a period of 2-3 hours. The HO. radicals then react with DNA to accomplish cleavage of DNA.

Abstract: There is disclosed numerous embodiments of a method and apparatus for a particle scanning system and an automatic inspection system. In each of these a particle beam is directed at the surface of a substrate for scanning that substrate. Also included are a selection of detectors to detect at least one of the secondary particles, back-scattered particles and transmitted particles from the substrate. The substrate is mounted on an x-y stage to provide it with at least one degree of freedom while the substrate is being scanned by the/particle beam. The substrate is also subjected to an electric field on it's surface to accelerate the secondary particles. The system also has the capability to accurately measure the position of the substrate with respect to the charged particle beam. Additionally, there is an optical alignment means for initially aligning the substrate beneath the,particle beam means.