Electromagnetic Attenuation Characteristics of Microbial Materials in the Infrared Band

Abstract

In this study, seven microbial materials (entomogenous fungi Bb3088 mycelia, entomogenous fungi Bb3088 spores, entomogenous fungi Ma2677 mycelia, entomogenous fungi Ma2677 spores, Bacillus subtilis 8204, Staphylococcus aureus 6725, and Saccharomyces cerevisiae 1025) were used to measure electromagnetic (EM) signal extinction. They were subjected to light absorption and reflection measurements in the range of 4000–400 cm⁻¹ (2.5–25 µm) using Fourier transform infrared spectroscopy. The specular reflection spectrum method was used to calculate the real (n) and imaginary (k) parts of the complex refractive index. The complex refractive index with real part n and imaginary part k in the infrared band satisfies the following conditions n ≥ 1 and k ≥ 0. The mass extinction coefficient was calculated based on Mie theory. Entomogenous fungi Ma2677 spores and entomogenous fungi Bb3088 spores were selected as EM signal extinction materials in the smoke box test. The transmittances of entomogenous fungi Bb3088 spores and entomogenous fungi Ma2677 spores were 11.63% and 5.42%, and the mass extinction coefficients were 1.8337 m²/g and 1.227 m²/g. These results showed that entomogenous fungi Bb3088 spores and entomogenous fungi Ma2677 spores have higher extinction characteristics than other microbial materials.