Photochemistry of Onium Salt Decomposition

Recent Developments of Versatile Photoinitiating Systems for Cationic Ring Opening Polymerization Operating at Any Wavelengths and under Low Light Intensity Sources

“…Iodonium (Iod) and sulfonium (Sulf) salts, originally proposed in the 1970s [ 33 , 34 ] (see also reviews in [ 5 , 29 ]) and extensively studied [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ] are the most widely used PIs for the CP of a large variety of monomers such as epoxides. In the near UV, the simplest Iod (diphenyl iodonium salt Ph 2 I + ) exhibits a less intense absorption (located at ~230 nm) than the corresponding triphenyl sulfonium salt Ph 3 S + (absorption at ~260 nm).…”

Benzophenothiazine and benzophenoxazine photosensitizers for triarylsulfonium salt cationic photoinitiators

“…Alternatively, photosensitization may occur but be highly inefficient. Depicted in Scheme is the general mechanism proposed for the electron‐transfer photosensitization of triarylsulfonium salts 6, 28. Essentially, this mechanism involves a photoinduced redox reaction in which the excited photosensitizer, PS*, transfers an electron to the ground‐state triarylsulfonium salt (eq 6).…”

Laser Flash Photolysis Studies on Chemically Amplified Resists 1. Femtosecond Laser Flash Photolysis of Diphenyliodonium Salts.

“…PhI'+ + Ph• -~ Ph2I+ (5) Although the absorption of PhI'+ has been observed by conventional flash photolysis (~, = 347 nm or 266 nm) of diphenyliodonium salts in acetonitrile [10][11][12][13], the fast decay components could not be detected because the decay was fast compared to the time resolution of their systems.…”

“…Although there are many previous studies on onium salts [1][2][3][4][5][6][7][8][9][10][11][12][13][14], the reaction dynamics in the very early stage have not been made clear yet. Recently, the advanced laser flash photolysis system with femtosecond laser pulses has been available to detect the rapid reactions.…”