measurements of the bulk 4(E)-ACBO in a form of a pellet, were carried out for the first time. The range of frequency was 42 Hz to 5 MHz and the temperature range was 303 K to 373 K.
All chemicals were obtained from Sigma Aldrich Company and used without further purification. All melting points of the investigated materials were recorded in open capillary tubes on a Stuart SMP3 melting point apparatus. Infrared spectra were recorded on FT-IR Bruker Vector 22 spectrophotometer using the KBr wafer technique. 4(E)-ACBO was synthesized by ring
–H bonds at 820 cm −1 and 794 cm −1 theoretically, which correlates nicely with an experimental peak at 800 cm −1 .
Methyl group vibrations
The title molecule possesses one C–H 3 group. The C–H methyl group stretching vibrations are highly localized and generally observed in the range of 3000 cm −1 to 2900 cm −1 [ 31 , 33 ]. In 7-Methoxy-4-methylcoumarin, the bands observed at 3001 cm −1 , 2964 cm −1 , 2951 cm −1 in FT-IR spectrum and the bands observed at 3000 cm −1 and 2951 cm −1 in Raman spectrum were assigned to CH 3 asymmetric stretching
Samir Meziani, Abderrahmane Moussi, Linda Mahiou and Ratiba Outemzabet
chemical composition of each layer in the ON structure. Hong et al. [ 20 ] determined that there is a direct correlation between the mass density of SiN x films and the concentration of Si–N bonds, as determined by FT-IR. In the meantime, Weeber et al. [ 21 ] have shown that the maximum Si–N bond concentration corresponds to stoichiometric SiN x (Si 3 N 4 ) with the refractive index in the vicinity of n = 2. Some authors reported that high surface passivation quality could be maintained for ARC SiN x or double antireflection coating (DARC) SiO 2 /SiN x after