Novel bis-onium salts and the use thereof as photoinitiators

DETAILED DESCRIPTION What is claimed is: 1.
A composition of matter comprising a material curable by a Bronsted acid, and a bis-sulfonium, -selenonium, -arsonium, -ammonium, or -phosphonium salt comprising: 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 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 x resonance between said aromatic or heterocyclic aromatic group and the other substituents in said salt; and two anions; said salt being capable, upon exposure to UV or visible radiation absorbed by said aromatic or heterocyclic aromatic group, of forming a Bronsted acid.
2.
A composition of matter comprising a material curable by a Bronsted acid, and a compound which has one of the following formulas: ##STR14## wherein: R.
sub.
1 represents an electron donating aromatic or heterocyclic aromatic group which absorbs UV or visible radiation and which exhibits a higher energy occupied molecular orbital greater than R.
sub.
3 and R.
sub.
6 ; R.
sub.
2 and R.
sub.
5 each, independently, represent the same substituent as R.
sub.
3 or R.
sub.
6 or an alkyl group having from 1 to 18 carbon atoms; L.
sub.
1 and L.
sub.
2 each, independently, represent a linking group which essentially prevents .
pi.
resonance between R.
sub.
1 and the remainder of the compound; R.
sub.
3 and R.
sub.
6 each, independently, represent an electron withdrawing alkyl, aryl or heterocyclic group, which electron withdrawing group causes the lowest unoccupied molecular orbital to be localized on R