An overtone vibrational spectrum of the organic molecule N-Methylaniline.
(a) Transmittance spectra of pure N-Methylaniline (NMA), pure hexane (Hex, black curves) and NMA diluted in Hex measured by Jasco V570 spectrophotometer recorded at room temperature of 21 ± 2 °C and converted to dB units. The inset (b) shows the absorption bands of NMA due to the (N-H)-bond stretching band around 1.5 μm and the aryl (C–H) overtone band around 1.65 μm in the ΔV = 2 region. Shift in location of the N-H band with respect to increase in concentration indicated by the dashed line. Arrows are pointing to a change in the signal strength and width. Skeletal molecular shape of NMA is shown in the inset (c). The quartz cuvette pathlength is 5 mm and the measurement was performed at normal incidence with air as reference. (d) Photograph of the pure NMA and diluted mixtures prepared for the measurement with colored concentration values corresponding to the colours of the spectral curves.