The rotational spectra belonging to the (28)Si isotopologue for three conformers of diethyldifluorosilane (Et(2)SiF(2)) and three conformers of diethylsilane (Et(2)SiH(2)) have been measured between 4 and 17 GHz by using pulsed-jet Fourier-transform microwave spectroscopy. Rotational spectra for the gauche-gauche, trans-trans, and trans-gauche conformers were identified for both molecules, while the significantly higher energy gauche-gauche' conformer was not observed. Ab initio calculations at the MP2(Full)/6-311+G(2d,2p) and MP2(Full)/6-311+G(2df,2pd) levels for the fluorine and the hydrogen analogues, respectively, provided rotational constants, dipole moment components, and the relative energies of the conformers to assist in the spectral assignment. In both molecules, the gauche-gauche conformer was identified by the ab initio calculations as the most stable. Agreement of the ab initio rotational constants with those from experiment was at worst 5%, with most rotational constants being predicted to within 2%.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/jp811049n | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Hydration behavior of asparagine: an approach using time domain reflectometry at low temperatures.
J Biomol Struct Dyn
December 2024
School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded, Maharashtra, India.
The dielectric behavior of Asparagine (CHNO) in water over the frequency range of 10 MHz to 30 GHz in the temperature region of 278.15-303.15 K in a step of 5 K has been carried out using time domain reflectometry (TDR) at various concentrations of asparagine.
View Article and Find Full Text PDFConformational Space of 3-Chloropropionic Acid in Gas Phase Explored by Rotational Spectroscopy.
J Phys Chem A
December 2024
Departamento de Química Física y Química Inorgánica, Facultad de Ciencias─I.U. CINQUIMA, Paseo de Belén, 7, 47011 Valladolid, Spain.
The conformational space of 3-chloropropionic acid has been studied under the isolated conditions of a supersonic expansion using Stark-modulated free-jet absorption millimeter-wave and centimeter-wave chirped-pulse Fourier transform microwave spectroscopy techniques. The rotational spectra originating from the three most stable conformers including Cl and Cl isotopologues were observed in both experiments using helium expansion while a partial conformational relaxation involving skeletal rearrangements takes place in an argon expansion. The rotational parameters, geometries, and energy order were determined from the experiment, allowing a comparison with quantum chemical predictions.
View Article and Find Full Text PDFVibronic Structure of the UV/Visible Absorption Spectra of Phenol and Phenolate: A Hybrid Density Functional Theory─Doktorov's Quantum Algorithm Approach.
J Phys Chem A
December 2024
Theoretical Chemistry Lab, Unit of Theoretical and Structural Physical Chemistry, Namur Institute of Structured Matter, University of Namur, Rue de Bruxelles, 61, Namur B-5000, Belgium.
The Doktorov's quantum algorithm has been enacted in combination with time-dependent density functional theory (TD-DFT) to simulate the vibronic structure of the UV/visible absorption spectra of the phenol and phenolate molecules. On the one hand, DFT and TD-DFT are employed with classical algorithms to calculate the ground and excited-state electronic structures as well as their vibrational frequencies and normal modes, whereas, on the other hand, quantum algorithms are employed for evaluating the vibrational transition intensities. In comparison to a previous study, , 128, 4369-4377, which demonstrated Doktorov's quantum algorithm as a proof of concept to predict the vibronic structure of ionization spectra, it is applied here to medium-size molecules with more than 30 vibrational normal modes, without accounting for Duschinsky rotations due to software limitations.
View Article and Find Full Text PDFHyperspectral (HS) imaging bridges conventional imaging into spectroscopy and generates a spatial map of spectral variations. On the one hand, in HS imaging, the effect of the background on the final spectra has to be removed or managed. On the other hand, there are important classes of materials that need to be immobilized for investigation.
View Article and Find Full Text PDFTunneling and conformational preferences in racemic- and meso-2,4-pentanediol: A rotational spectroscopic and theoretical investigation.
J Chem Phys
December 2024
Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
The rotational spectra of a mixture of 2,4-pentanediol (PDL) isomers, comprising both the meso isomers [(2R, 4S) and (2S, 4R)] and the racemic isomers [(2R, 4R) and (2S, 4S)], were recorded using a chirped-pulse Fourier transform microwave spectrometer coupled to a supersonic jet expansion. The conformational landscapes of meso- and racemic-PDL were examined using the Conformer-Rotamer Ensemble Sampling Tool and high-level quantum chemical calculations, generating 26 and 25 conformers, respectively. Five sets of rotational transitions were observed and assigned, with two attributed to meso-PDL and the remaining three attributed to racemic-PDL.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!