Determination Of Excitation Spectra Research Articles

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.

ChemInform Abstract: C‐H Activation by Organometallics: The Role of Matrix Isolation Studies

Advances are reported in the application of matrix isolation in combina- tion with solution techniques to the study of C-H activation reactions of organo- metallics. Laser-induced fluorescence proves applicable to all the open-shell metallocenes studied, (75-CsHs) M (M = Mo, W, Re) and (75-C5Me5),Re. Studies with pulsed dye-lasers allow the determination of excitation spectra and the emission lifetimes. Three types of situation are encountered when the behaviour of photoproducts in matrices is compared with that in solution. In the type 1 situation, a coordinatively unsaturated intermediate is stabilised by the matrix. It may be observed in solution using time-resolved spectroscopy if the matrix and solution studies share a common spectroscopic technique (e.g. Ru(Me,PCH,CH,PMe,),). In type 2 reactions, photolysis leads to an unstable isomer of the precursor. Such species may often be observed by NMR following photolysis of solutions or frozen solutions at low temperature. The cage formed by the matrix or viscous solvent may play a significant role in this type of reaction as, for instance, in the isomerisation of some metal-ethene complexes. Type 3 reactions involve intermolecular reaction in the matrix (e.g. (75.-C5H )Rh(CO), with methane), but the products of reaction may be very labile. ?he corresponding reactions with alkanes may be observed by laser flash photolysis with the aid of a common spectroscopic method.

C-H activation by organometallics: the role of matrix isolation studies

Abstract

Determination of Excitation Spectra with a Recording Spectrophotometer

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of Excitation Spectra with a Recording SpectrophotometerC. W. SillCite this: Anal. Chem. 1961, 33, 11, 1579–1584Publication Date (Print):October 1, 1961Publication History Published online1 May 2002Published inissue 1 October 1961https://doi.org/10.1021/ac60179a037RIGHTS & PERMISSIONSArticle Views85Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts Get e-Alerts