▁An ▁example ▁due ▁to ▁phot od is soci ation ▁is ▁tri phen yl s ulf on ium ▁trif late ▁with ▁the ▁formula ▁[( C 6 H 5 ) 3 S + ][ CF 3 SO ]. ▁ ▁This ▁colour less ▁salt ▁consists ▁of ▁a ▁sul fon ium ▁c ation ▁and ▁the ▁trif late ▁an ion . ▁ ▁Many ▁related ▁sal ts ▁are ▁known ▁including ▁those ▁with ▁other ▁non co ordin ating ▁an ions ▁and ▁those ▁with ▁diverse ▁subst itu ents ▁on ▁the ▁phen yl ▁rings . ▁ ▁The ▁tri phen yl s ulf on ium ▁sal ts ▁abs orb ▁at ▁ 2 3 3   nm , ▁which ▁indu ces ▁the ▁series ▁of ▁re actions ▁shown ▁below . ▁As ▁this ▁series ▁of ▁re actions ▁is ▁irre vers ible , ▁tri phen yl s ulf on ium ▁trif late ▁is ▁a ▁photo ac id ▁generator . ▁ ▁[( C 6 H 5 ) 3 S + ][ CF 3 SO ] ▁ ▁+ ▁ ▁h ν ▁▁ ▁→ ▁ ▁[( C 6 H 5 ) 2 S + . ][ CF 3 SO ] ▁ ▁+ ▁ ▁C 6 H ▁[( C 6 H 5 ) 2 S + . ][ CF 3 SO ] ▁ ▁+ ▁ ▁C 6 H ▁▁ ▁→ ▁ ▁( C 6 H 5 C 6 H 4 )( C 6 H 5 ) S ▁ ▁+ ▁ ▁[ CF 3 SO ][ H + ] ▁ ▁App lications ▁of ▁these ▁photo ac ids ▁include ▁phot ol ith ography