Department of Physics, SCSVMV University, Enathur, Kanchipuram 631561, India; Department of Physics, Pallavan College of Engineering, Kanchipuram 631502, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Jan 3;117:557-67. doi: 10.1016/j.saa.2013.08.061. Epub 2013 Aug 27.
The spectroscopic properties of the p-nitroacetanilide (PNA) were examined by FT-IR, FT-Raman and UV-Vis techniques. FT-IR and FT-Raman spectra in solid state were observed in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The UV-Vis absorption spectrum of the compound that dissolved in ethanol was recorded in the range of 200-400 nm. The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional theory (DFT) employing B3LYP methods with the 6-31G(d,p) and 6-311+G(d,p) basis sets. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Thermodynamic properties like entropy, heat capacity and enthalpy have been calculated for the molecule. HOMO-LUMO energy gap has been calculated. The intramolecular contacts have been interpreted using natural bond orbital (NBO) and natural localized molecular orbital (NLMO) analysis. Important non-linear optical (NLO) properties such as electric dipole moment and first hyperpolarizability have been computed using B3LYP quantum chemical calculation.
通过傅里叶变换红外光谱（FT-IR）、傅里叶变换拉曼光谱（FT-Raman）和紫外可见光谱（UV-Vis）技术研究了对硝基乙酰苯胺（PNA）的光谱性质。在固态下分别观察到了在 4000-400 cm(-1) 和 3500-100 cm(-1) 范围内的 FT-IR 和 FT-Raman 光谱。该化合物在乙醇中的紫外可见吸收光谱在 200-400nm 范围内记录。采用密度泛函理论（DFT），使用 B3LYP 方法，在 6-31G(d,p)和 6-311+G(d,p)基组上计算了分子在基态下的结构和光谱数据。通过全优化分子几何形状，计算了振动光谱，并根据振动模式的总能量分布（TED），利用标度量子力学（SQM）方法对基本振动进行了分配。计算了分子的热力学性质，如熵、热容和焓。计算了 HOMO-LUMO 能隙。利用自然键轨道（NBO）和自然局域分子轨道（NLMO）分析解释了分子内的接触。使用 B3LYP 量子化学计算计算了重要的非线性光学（NLO）性质，如电偶极矩和第一超极化率。
