Alpha 2 fourier transform infrared ft ir spectrometer

We used a Bruker ALPHA II Fourier-Transform Infrared (FT-IR) spectrometer with attenuated total reflectance (ATR) to measure the infrared spectrum of the dried mosquito samples. Prior to scanning, the head and thorax of each mosquito was carefully separated from the abdomen, ensuring that only the head and thorax regions were scanned. The mosquito heads and thoraces were placed on the infrared optical window, and pressure was applied to ensure maximum direct contact between the sample and the diamond crystal. The spectral signal was obtained at frequencies between 4000 and 400 cm⁻¹, with a resolution of 2 cm⁻¹. Each spectrum was an average of 32 scans of a single mosquito sample, with band intensity recorded as an absorbance. Following scanning, the remaining of the mosquito head and thorax (carcasses) were individually packed in 1.5 mL tubes for subsequent molecular analysis. The recorded spectra were pre-processed by compensating for carbon dioxide interference bands and water vapor absorption bands as previously described^{22 (link)}. Additionally, spectra with no intensity (i.e. flat spectra) and low intensity (i.e. < 0.11 absorbance units) were removed before machine learning steps^{22 (link)}.

X-ray diffraction (XRD) measurements were performed on a PANalytical X’Pert Pro MPD powder diffractometer with a Cu Kα X-ray source (λ = 0.154 nm). Scanning electron microscopy (SEM) images, along with energy-dispersive X-ray spectroscopy (EDX) measurements, were acquired using a JEOL model JSM-7500FA which was operated at 3 or 5 keV. The Transmission electron microscopy (TEM) used for the analysis was a JEOL JEM-2200FS and operated at 200 keV. A Fourier transform infrared (FTIR) ALPHA II Fourier-transform infrared (FTIR) spectrometer from Bruker was employed for infrared spectroscopy which was equipped with an Attenuated Total Reflection (ATR) module. The spectra were taken from 4000 to 400 cm⁻¹ in absorbance mode. The electronic conductivity of electrodes was measured using a Jandel RM 3000 four points probe using currents between − 5 and 5 μA. For all these techniques, samples were transferred using a special sample holder that maintains vacuum conditions. In other words, the samples were not exposed to the atmosphere.