Table 2: Absorption of some chromospheres’ or radicals groups which contain C, H, O or N, and can be formed on surface of PET caused by ion bombardment during plasma treatment [31].

Name	Chromophores or Radicals	λ_max (nm)
Aromatic	Benzene nucleus	204
Alkene	C₅H₁₃CH=CH₂	256
Conjugated alkene	CH₂=CH-CH=CH₂	217
Alkyne	C₅H₁₁C≡C-CH₃	178
Amide	(C₆H₁₀O₅)_n	214
Azo	CH₃-N=N-CH₃	339
Carbonyl	$C H_{3} - \overset{\overset{O}{∥}}{C} - C H_{3}$	186
Carboxyl		204
Nitro	CH₃-NH₂	280
Nitrous	C₄H₉-NO	300
Nitrate	C₂H₅ONO₂	270