Ft-Ir Spectroscopic Analysis Essay

The FT-Raman and FT-IR spectroscopic analysis of 2'-nitroacetophenone (2NAP) were performed. The vibrational spectra of 2NAP was found by applying the Density Functional Theory Calculations based on Beck3-lee-yang-parr (B3LYP) level with the use of the standard 6-31G*/6-311+G** basis set. The vibrational wave number for the optimized geometry was calculated at the same level of theory. The computed values of frequencies are scaled using an appropriate scale factor to give up the excellent unity with the observed values. Detailed interpretations of the infrared and Raman spectra of 2NAP are reported. The theoretical spectrograms for FT-IR spectra of the title molecule have been constructed. The 1H and 13C nuclear magnetic resonance (NMR) chemical shift of the molecules are calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. Further, density functional theory (DFT) combined with quantum chemical calculations were done to find out the first-order hyperpolarizability. The calculated HOMO and LUMO energies shows that charge transfer occur within the molecule. Electronic excitation energies, oscillator strength and nature of the respective …show more content…
For the plots of simulated IR and Raman spectra, pure Lorentzian band shapes were used with a band width (FWHM) of 10 cm−1. The vibrational modes were assigned by means of visual inspection using the GAUSS VIEW program [11]. The analysis for the vibrational modes of 2NAP is presented in some detail in order to better describe the basis for the assignments. From the basic theory of Raman scattering, Raman activities (si) calculated by GAUSSIAN 09W program has been converted to relative Raman intensities (Ii) using the following