Virtual Vibrational Spectrometry of Stable Radicals—Necklaced Graphene Molecules

Abstract

The article presents results of an extended virtual experiment on graphene molecules performed using the virtual vibrational spectrometer HF Spectrodyn that exploits semiempirical Hartree-Fock approximation. The molecules are composed of flat graphene domains surrounded with heteroatom necklaces. Not existing individually, these molecules are met in practice as basic structure units of complex multilevel structure of all sp2 amorphous carbons. This circumstance deprives the solids’ in vitro spectroscopy of revealing the individual character of basic structural elements, and in silico spectrometry fills this shortcoming. The obtained virtual vibrational spectra allow for drawing first conclusions about the specific features of the vibrational dynamics of the necklaced graphene molecules, caused by spatial structure and packing of their graphene domains as well as by chemical composition of the relevant necklaces. As shown, IR absorption spectra of the molecules are strongly necklace dependent, once becoming a distinct spectral signature of the amorphous body origin. Otherwise, Raman spectra are a spectral mark of the graphene domain’s size and packing, thus disclosing the mystery of their universal D-G-band standard related to graphene-containing materials of various origins.

Virtual Vibrational Analytics of Reduced Graphene Oxide

“…A detailed description of the code is given elsewhere [17]. All of the calculations discussed in the current paper were performed using the AM1 version of the code in the UHF approximation since all of the studied DTs are open-shell molecules [13,18]. It should be noted that such an approach, similar in essence, but less categorically formulated, was practically realized by Yamada's team previously by applying to both rGO and graphene oxide (GO) [19].…”

“…A comprehensive VVS analysis of IR absorption and the Raman scattering spectra of bare graphene domains has only recently been conducted. [13]. In light of the analytic focus of the current study, there is a need to briefly repeat its main issues.…”

“…The recent development of virtual vibrational spectrometry (VVS) [9][10][11][12][13] offers an attractive opportunity for significant advancement in this task. Based on a virtual vibrational spectrometer HF Spectrodyn [10], it turned out to be possible to consider nanosized NGMs compatible in the size and composition of heteroatomic necklaces with real basic structural units (BSUs) of sp 2 amorphous carbons [13]. The obtained results allow us to suggest general grounds of virtual vibrational analytics (VVA) applied to complicated carbon materials such as rGO.…”

“…Digital twins (DTs) and a proper computational code constitute the VVA core. The former, as in the previous cases [13], is presented with a number of NGMs, specified with the same (5,5) graphene domain, once graphene molecules, but differing by largely variable heteroatom necklaces. The domain is a squared honeycomb sheet with 5 benzenoid units along the armchair and zig-zag edges, respectively.…”

The Effects of Graphene-Family Nanomaterials on Plant Growth: A Review

“…In many studies, the properties of these substances can be further identified using Raman spectroscopy [ 30 , 32 , 35 ], which is a simple, fast, and nondestructive detection technique [ 36 ]. The D band (located near 1350 cm −1 ) and G band (located near 1580 cm −1 ) can be used as the two main representative Raman peaks for GFNs [ 37 , 38 ].…”