AM1 and DFT: Conformational and vibrational spectra analysis of butyl methacrylate

Semi-empirical infrared spectra simulation of pyrene-like molecules insight for simple analysis of functionalization graphene quantum dots

The Infrared (IR) spectra usually assume the samples are 3D materials. Thus, it is difficult to identify functional groups in 2D materials at the edge and the center of the 2D surface. Therefore, it is crucial to introduce analysis methods that enable the investigation of 2D carbon materials such as graphene and its derivatives using IR spectra. This study calculates the infrared spectra of pyrene-like molecules as an insight for a simple analysis of graphene quantum dots using a semi-empirical method. These IR spectra were correlated to the electronic transition and charge distribution associated with functional groups. The IR spectra analysis focuses on comparing the pristine and functionalized molecule at the wavenumber 1400-2000 cm^-1_, especially to identify the C=C stretching mode and 3000-3500 cm^-1 for C-H and OH stretching. Moreover, the determination of excitation spectra was carried out to analyze the electronic transition of the molecules in the ultraviolet-visible region (200-900 nm) calculated using ZINDO method. The investigation of the pyrene-like GQD permitted the identification of the edge and center surface functionalization in 2D carbon materials.

Correlating Nanostructure, Optical and Electronic Properties of Nanogranular Silver Layers during Polymer-Template-Assisted Sputter Deposition

Tailoring the optical and electronic properties of nanostructured polymer-metal composites demonstrates great potential for efficient fabrication of modern organic optical and electronic devices such as flexible sensors, transistors, diodes, or photovoltaics. Self-assembled polymer-metal nanocomposites offer an excellent perspective for creating hierarchical nanostructures on macroscopic scales by simple bottom-up processes. We investigate the growth processes of nanogranular silver (Ag) layers on diblock copolymer thin film templates during sputter deposition. The Ag growth is strongly driven by self-assembly and selective wetting on the lamella structure of polystyrene-block-poly(methyl methacrylate). We correlate the emerging nanoscale morphologies with collective optical and electronic properties and quantify the difference in Ag growth on the corresponding homopolymer thin films. Thus, we are able to determine the influence of the respective polymer template and observe substrate effects on the Ag cluster percolation threshold, which affects the insulator-to-metal transition (IMT). Optical spectroscopy in the UV-vis regime reveals localized surface plasmon resonance for the metal-polymer composite. Their maximum absorption is observed around the IMT due to the subsequent long-range electron conduction in percolated nanogranular Ag layers. Using X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy, we identify the oxidation of Ag at the acrylate side chains as an essential influencing factor driving the selective wetting behavior in the early growth stages. The results of polymer-templated cluster growth are corroborated by atomic force microscopy and field emission scanning electron microscopy.

FT-IR and FT-Raman spectra of 2-hydroxyethyl methacrylate--A conformational and vibrational analysis

A conformational search of the flexible 2-hedroxyethyl methacrylate molecule by semi-empirical AM1 and B3LYP formalisms leads to six stable conformations. Four of them are in the s-trans conformation. The optimized geometries at DFT using 6-311+G(∗∗) basis set are in good agreement with experimental electron diffraction data of the methyl methacrylate molecule, thereby the s-trans is the most stable form. The harmonic frequencies at the fully optimized geometries of all conformers have been performed at the DFT//B3LYP/6-311+G(∗∗) level of theory. Infrared and Raman intensities and potential energy distributions of the scaled harmonic frequencies are used for the assignment of the observed IR and Raman bands. We noticed a good agreement between the experimental and the computed spectra. The strong band at 1081 cm(-1), in the infrared spectrum, maybe used as a characteristic band of the s-trans conformation. Henceforth, the less stable structure contribute alone for reproducing the Raman bands located at 276 (sh) and 3020 (vw) cm(-1).