Abstract: Sulfonium and oxysulfonium salts, useful as photoinitiators, have directly attached to the sulfur atom thereof:at least one aromatic or heterocyclic aromatic substituent containing at least 14 aromatic atoms and having a removable positive hydrogen ion, said substituent exhibiting a higher energy occupied molecular orbital than at least one other substituent directly attached to said sulfur atom;and at least one substituent comprising an electron withdrawing group and exhibiting a lower energy unoccupied molecular orbital than at least one other substituent directly attached to said sulfur atom;said salt being capable, upon exposure to visible radiation, of undergoing irreversible intramolecular rearrangement to form a Bronsted acid comprising the anion of said salt and said removable positive hydrogen ion.

Abstract: Sulfonium, selenonium, arsonium, ammonium and phosphonium salts, useful as photoinitiators, comprise:a chromophore which absorbs visible radiation, the chromophore (1) having a removable positive hydrogen ion and (2) exhibiting a higher energy occupied molecular orbital than at least one other substituent attached to the S, Se, As, N or P atom of the salt;an insulating group which links the chromophore to the S, Se, As, N or P atom of the salt, the insulating group essentially preventing .pi. resonance between the chromophore and the other substituents in the salt;at least one substituent comprising an electron withdrawing group and exhibiting a lower unoccupied molecular orbital than the chromophore; and,an anion;the salts being capable, upon exposure to visible radiation, of forming a Bronsted acid.

Abstract: Bis-sulfonium, -selenonium, -arsonium, -ammonium, and -phosphonium salts useful as photoinitiators, comprise:an aromatic or heterocyclic aromatic group which absorbs UV or visible radiation and which exhibits a higher energy occupied molecular orbital than at least one other substituent attached to each of the S, Se, As, N or P atoms of said salt;at least one substituent, attached to each of the S, Se, As, N or P atoms of said salt, which comprises an electron-withdrawing group which causes the lowest unoccupied molecular orbital to be localized on the substituent and the S, Se, As, N or P atom of the salt;an insulating group which links said aromatic or heterocyclic aromatic group to each of the S, Se, As, N, or P atoms of said salt, said insulating group essentially preventing .pi.

Abstract: Compositions of matter are provided which comprise a material curable by a Bronsted acid, and a photoinitiator salt having the formula: ##STR1## wherein: R.sup.1 represents an electron-donating chromophore group which absorbs visible radiation and which exhibits a higher energy occupied molecular orbital than at least one of R", R'" and R"";R" represents the same substituent as R' or R'", an optionally substituted aryl group or an optionally substituted alkyl group having from 1 to 18 carbon atoms;R'" represents an electron-withdrawing alkyl, aryl or heterocyclic group;R.sub.1 and R.sub.2 each, independently, represents hydrogen or an electron-donating group;J represents an S, Se, As, N or P atom; andwhen J represents As, N or P, R"" represents the same substituent as R', R" or R'", and when J represents an S or Se atom, R"" represents O or an electron pair; andW.sup..THETA.

Abstract: An impact target for a fluid energy mill comprises a plurality of impact plates arranged in series in spaced relationship alone and generally perpendicular to the axis of a discharge conduit. All but one of the plates has an open area in the central portion thereof and an impact area surrounding the open area. The size of the open area diminishes with the distance of the plate from the discharge conduit.

Abstract: Development of electrostatic charge patterns (e.g., electrostatic latent images) carried on a support is accomplished in an electrographic process in which during development, an electrical field which is greater than the electrical breakdown value of the developer (i.e., greater than the maximum electrical field that the developer can support without undergoing electrical breakdown) is established across the developer in the development area. The process enables development of high quality, large solid-area images at high processing rates.