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.
磺鎵、
硒鎵、
砷鎵、銨和
磷鎵鹽,作為光引發劑有用,包括:一個吸收可見光輻射的色团,該色团(1)具有可拆卸的正氫離子,且(2)展現出比鹽中連接到S、Se、As、N或P原子的至少一個其他取代基更高的占据能级分子軌道;一個絕緣基團,將色团與鹽中的S、Se、As、N或P原子連接起來,該絕緣基團基本上防止色团和鹽中的其他取代基之間的π共振;至少一個取代基包括一個提取電子基團,並展現比色团更低的未占据分子軌道;以及一個陰離子;該鹽能夠在暴露於可見光輻射時形成布朗斯特酸。