Combined analysis of static and dynamic extinction characteristics of microbial spores and mycelia as a mid-infrared extinction material

The extinction characteristics of microbial materials have always played an important role in identification of microbial materials. To evaluate the extinction properties of microbial materials comprehensively, a method via combined static and dynamics analysis extinction performance is presented, combining with the reflection spectra measured by a Nicolet FT-IR spectrometer, and transmittance determined by smoke box test of microbial materials in 3 ∼ 5 μm. In the case of static analysis, the complex refractive indices of microbial spores and mycelia were retrieved by using Kramers-Kronig (KK) transform and an iterative method on the basis of the reflection spectrum exponential extrapolation method. Based on Mie theory, the mass extinction coefficients of microbial spores are 15.58%, 28.07%, and 36.72% greater than those of the corresponding mycelia respectively. While in the dynamic analysis, in the terms of Beer-Lambert law, the mass extinction coefficients of microbial spores are 31.83%, 21.63%, and 68.42% greater than those of the corresponding mycelia respectively. It is shown that mid-infrared extinction performance of microbial spores are always better than those of corresponding microbial mycelia. The results show that the method is practicable and play an important role in finding strong mid-infrared extinction microbial materials.