Global Journal of Science Frontier Research, H: Environment & Earth Science, Volume 23 Issue 1

All the spectral features related to the H–F, C=O, and C–H stretches and the HF librational vibrations in the H 2 CO···HF complex. In contrast with studied complexes in [1], in this work, the ν (HF) region is complicated spectral features are not observed upon the complex formation. Due to following reasons, complicated spectral patterns have not observed: firstly, C=O and HF stretching vibrations are weakly interacting mutually in the complex. Secondly, the mechanical anharmonic constant of the HF molecule is sufficiently large and equals 85 cm -1 . Thirdly, the H 2 CO molecule keeps the inclination to polymerization even in the case of low concentrations. Therefore, we are not considering the focus ν (HF) region of the complex. It requires further experimental investigations at a convenient condition and with the help of unique spectroscopic techniques. Fig. 2. shows ν (C−H) stretching region of the H 2 CO···HF complex and H 2 CO molecule. In the spectrum, R, Q, and P branches have observed, respectively. The yellow spectrum (c) belongs to the pure H 2 CO molecule at pressure p=0.006 kgf/cm 2 ,and green (b) belongs to the complex which is recorded at p=90 Torr and at blue (a) belongs to the complex p= 65 Torr, respectively. All spectra were recorded at the 0.05 c м -1 spectral resolution. b) Computational Part Quantum chemical calculations on the H 2 CO···HF complex have been carried out with using the GAUSSIAN 16 software in the mp2/6-311++G(3df,3pd) approximation with the basis set superposition error taken into account. This approximation provides accurate information for the spectral parameters of the complex. The band changes (blue or red), of the frequency, and intensity changes have been explained in [4] in detail. The equilibrium geometry of the H 2 CO···HF complex is presented in Fig.3. Selected geometrical parameters of the complex have shown in table 1. a b c lg(I 0 /I) ν, cm -1 Investigation of Formaldehyde+Hydrogen Fluoride Complex in Gas Phase by the Help of Ftir Spectroscopy and Computational Methods 1 Year 2023 17 © 2023 Global Journals Global Journal of Science Frontier Research Volume XXIII Issue ersion I VI ( H ) Figure 2: Infrared absorption spectra of pure H 2 CO and HF+ H 2 CO complex in the gas phase in the ν (CH) stretching region. (yellow-(c), pure H 2 CO p=0.006 kgf/cm 2 , green (b) HF+ H 2 CO complex p=90 Torr and blue (a), HF+ H 2 CO complex 65 Torr)