-continued  group, an arylene group, a carbonyl group, a sulfonyl group,  a carbonyloxy group, a carbonylamino group, a sulfonyla› mido group, an ether group, a thioether group, an amino  group, a disulfide group, an acyl group, an alkylsulfonyl  group,  ----CH=CH-, -C=C-,  an aminocarbonylamino  group, an aminosulfonylamino group or the like. The bivalent  connecting group may have a substituent. The same substitu› ents as mentioned above with respect to R  1  to R $^{13 }$can be  employed. Preferably, Z is a single bond or a substituent  exhibiting no electron withdrawing properties, such as an  alkylene group, an arylene group, an ether group, a thioether  group, an amino group,  ----CH=CH-,  an aminocarbony› lamino group or an aminosulfonylamino group. More prefer› ably, Z is a single bond, an ether group or a thioether group.  Most preferably, Z is a single bond.  Specific examples of the onium ions of the general formula  (VIII) will be shown below, which are however nonlimiting.  42  US 8,900,791 B2  41  (A4)  OH  (A5)  OH  (A6)  OH  (A7)  O ~0H  V  (A3)  OH  ~  (A2)  OH  (Al)  OH  ~ 