수정진동자를 이용한 프탈로시아닌 LB박막의 NO2 감지 특성 = The Application of Octa - Substituted Metallophthalocyanine Langmuir - Blodgett Films for NO2 Measurement

다국어 초록 (Multilingual Abstract)

Multilayer Langmuir-Blodgett (LB) films coated on quartz crystal microbalance (QCM) of octa-substituted metallophhtalocyanines (MPc(OEH)_8, M = Cu, Co, and Sn) and dihydrogen phthalocyanines (H₂Pc(OEH)_8) were used to quantify NO₂ concentrations. They were exposed to various concentrations of NO₂ in dry N₂. Among the four phthalocyanines we tested, the metal-free H₂Pc(OEH)_8 was observed to be m48t sensitive to NO₂. However, its LB film showed a partially irreversible behavior, that is part of the frequency change due to NO₂ adsorption could not be recovered even after purging with pure N₂ gas for an extended period. Examining the spectra of NMR and FTIR revealed fact that the irreversible portion of frequency change was due to ether groups in the linkage between side chains and the Pc unit. In order to remove the effect of such initial deactivation, on NOD quantification experiment, a freshly fabricated LB film was treated at a high concentration of NO₂ so that the ether sites were saturated. A pretreated LB film showed a reproducible performance for repeated uses. The CuPc(OEH)_8 LB film showed a satisfactory sensing performance down to as low as 4 ppm. For the H₂Pc(OEH)_8 LB film, the lower detection limit was found to be 35 ppb of N02. In order to make the experimental condition more realistic, the carrier gas, dry nitrogen, was replaced by air. It was observed that the presence of oxygen, a weak electron acceptor, reduced the sensitivity and thus increased the sensing limit to hundreds of ppb. Results of experiments with moisture added showed that the interference of moisture was quite severe.