Optical gas sensing of hematin Langmuir-Blodgett films

This paper reports the use of hematin Langmuir-Blodgett (LB) films to detect carbon monoxide gas at the room temperature, based on changes in the optical absorption of the films. Hematin LB films were deposited on quartz and glass substrates. For the film deposited on quartz substrate, an increase in the absorption spectra of the film was achieved by exposing the film to carbon monoxide gas. The absorption spectra of the film recover back when the exposing gas was cut off. While for the film deposited on glass substrate, there is no significant change in the spectra due to this gas. Atomic force microscope images were taken for the hematin LB films both on glass and quartz substrates. Both images show different features indicating that the optical respond of the films to the gas depends on the arrangement of molecules on the substrate.