Optical response of monolayer films of a metal-free sulfonamido-porphyrin

• Autor(a) principal: Richardson, T.
• Data de Publicação: 1998
• Outros Autores: Smith, V. C., Johnstone, R. A. W., Sobral, A. J. F. N., Rocha-Gonsalves, A. M. d'A.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/5280; https://doi.org/10.1016/S0040-6090(98)00652-X
• topic: Chlorine; Porphyrin; Langmuir-Blodgett

The influence of gaseous chlorine on monolayers of metal-free meso-tetra(4-amino sulfonyl)phenylporphyrin is discussed. These films exhibit characteristic intense optical absorption bands in the region 400-700 nm. Upon exposure to chlorine vapour in the concentration range 0.1-10 ppm, the Soret and Q-bands decrease in intensity and new bands at ~455 nm and ~660 nm appear. The rate of response has been measured as a function of deposition surface pressure and gas concentration. Repeated dosing experiments have shown that reversible and reproducible sensing action occurs provided that a threshold concentration is not exceeded. The recovery of the original optical spectrum can be accelerated with moderate heat treatment (60°C for 10 min). Ageing experiments have shown that the basic response of the monolayer is not effected over a time period of at least 5 months.