12  US 8,652,712 B2  11  II. Specifically, and in one embodiment, PAGs p+ A-, com- prise:  1. p+ comprising;  where E comprises a strong electron-withdrawing substitu› ent, and in one embodiment this substituent comprises low  photoabsorption cross-section in EUV, comprising the cyano  group CN. However, the electron-withdrawing group is not  limited to the cyano group (CN), but E can be the same or  different. Other substituents, E, comprise an alkyl, alkyloxy,  hydrogen, nitro, alkoxycarbonyl, halogen, aryl, aryloxy or  aryloxycarbonyl group. These anions with low EUV absorp› tion are not limited to the anions 4, 5, 6 and 7; but could be  anions of carboranes and other art-known anions as well that  also exhibit low EUV absorption. R. P. Meagley, United  States Patent Appl. 2005/0221220 gives examples of such  carboranes.  Disclosed anions A-, however, can also comprise aliphatic  sulfonates, comprising perfluoroaliphatic sulfonates, substi› tuted or unsubstituted arylsulfonates, when used in conjunc- tion with a cation p+ that comprise atoms with high photoab› sorption cross-section in EUV light.  PAGs p+ A- of the invention comprise cations p+, atoms  with high photoabsorption cross-section in EUV, such as the  above-mentioned sulfonium, selenium or iodonium cations  comprising fluorine as substituents of the groups  R$_{1}$ ,  R$_{2}$ ,  and/or R$_{3}$ ,  and of anions A- comprising atoms with low  photoabsorption cross-section in EUV, comprise, e.g., such  above-mentioned cyclic organic anions that are substituted  with strong electron withdrawing groups, comprising e.g.  CN.  2. A- comprises the anion of a very strong acid, compris› ing:  a),  F  F  F  F  ,::::,,0  ;/’o- F  F  F  0  and d),  b) a selenium cation, comprising;  c) an iodonium cation, comprising,  a) a sulfonium cation, comprising,  4  E  F*F  E  E  E  E  E  E  E  E  E  E  E  E  E  E  7  E  E  E  E  E 