scholarly journals Direct Measurements of Small Polar Impurities in Gasoline Mixtures Using Molecular Rotational Resonance Spectroscopy

2019 ◽  
pp. 000370281985901
Author(s):  
Artressa L. Christophe ◽  
Jalon T. Barnes ◽  
Sylvestre Twagirayezu ◽  
Aleksandr Mikhonin ◽  
Matthew T. Muckle ◽  
...  
Keyword(s):  
Polar Compounds ◽  
Resonance Spectroscopy ◽  
Rotational Spectrum ◽  
Rotational Resonance ◽  
Rotational Spectra ◽  
Direct Measurements ◽  
Commercial Gasoline ◽  
Standard Linear ◽  
Petroleum Analysis ◽  
Ethanol In Water

This paper reports our efforts to determine whether rotational spectroscopy is a useful tool for petroleum analysis. These efforts include the use of a BrightSpec molecular rotational resonance (MRR) spectrometer, which operates in the 260–290 GHz frequency range, to record rotational spectra of small polar contaminants in commercial gasoline. The observed rotational spectra showed rich, but assignable, patterns due to the sensitivity of the MRR to only small polar compounds. Any interference from a complex hydrocarbon matrix, which in conventional chromatographic methods obscures signals from small polar contaminants, is nearly eliminated. In addition to the evident rotational spectrum of ethanol, the spectra of toluene, ethyl cyanide, and acetaldehyde have also been detected. A quantitative method for ethanol has been developed and demonstrated in this paper, whereas the specific analyses of the other polar impurities will be reported in the future. The validity of MRR to be used as an analytical instrument has been examined by constructing a standard linear curve using dilutions of ethanol in water. The linearity and percentage recovery parameters are satisfactory.

scholarly journals Understanding (coupled) large amplitude motions: the interplay of microwave spectroscopy, spectral modeling, and quantum chemistry

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ha Vinh Lam Nguyen ◽  
Isabelle Kleiner
Keyword(s):  
Fourier Transform ◽  
Quantum Chemistry ◽  
Large Amplitude ◽  
Environmental Chemistry ◽  
Broad Band ◽  
Microwave Spectroscopy ◽  
Rotational Spectrum ◽  
Spectral Modeling ◽  
Rotational Spectra ◽  
Large Amplitude Motions

AbstractA large variety of molecules contain large amplitude motions (LAMs), inter alia internal rotation and inversion tunneling, resulting in tunneling splittings in their rotational spectrum. We will present the modern strategy to study LAMs using a combination of molecular jet Fourier transform microwave spectroscopy, spectral modeling, and quantum chemical calculations to characterize such systems by the analysis of their rotational spectra. This interplay is particularly successful in decoding complex spectra revealing LAMs and providing reference data for fundamental physics, astrochemistry, atmospheric/environmental chemistry and analytics, or fundamental researches in physical chemistry. Addressing experimental key aspects, a brief presentation on the two most popular types of state-of-the-art Fourier transform microwave spectrometer technology, i.e., pulsed supersonic jet expansion–based spectrometers employing narrow-band pulse or broad-band chirp excitation, will be given first. Secondly, the use of quantum chemistry as a supporting tool for rotational spectroscopy will be discussed with emphasis on conformational analysis. Several computer codes for fitting rotational spectra exhibiting fine structure arising from LAMs are discussed with their advantages and drawbacks. Furthermore, a number of examples will provide an overview on the wealth of information that can be drawn from the rotational spectra, leading to new insights into the molecular structure and dynamics. The focus will be on the interpretation of potential barriers and how LAMs can act as sensors within molecules to help us understand the molecular behavior in the laboratory and nature.

Fourier transform molecular rotational resonance spectroscopy for reprogrammable chemical sensing

2015 ◽  
Author(s):  
Brent J. Harris ◽  
Robin L. Pulliam ◽  
Justin L. Neill ◽  
Matt T. Muckle ◽  
Roger Reynolds ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Chemical Sensing ◽  
Resonance Spectroscopy ◽  
Rotational Resonance

The Rotational Spectrum of Monothioformic Acid. I. cis-and trans-HC(:O)SH1,2

1976 ◽  
Vol 31 (5) ◽  
pp. 422-437
Author(s):  
William H. Hocking ◽  
Gisbert Winnewisser
Keyword(s):  
Frequency Region ◽  
Absorption Lines ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Astrophysical Interest ◽  
Rotational Spectra ◽  
Measured Line ◽  
Centrifugal Distortion Constants ◽  
Cis And Trans ◽  
Line Positions

Abstract The rotational spectra of the two abundant isomers of monothioformic acid, cis- and trans- HC(:O)SH, have been assigned in the frequency region 8 -250 GHz. Over 90 a-type transitions and over 60 b-type transitions have been measured for each rotamer. The a-type transitions belong to the qRK , qQ1, qQ2, qQ3 and qQ4 branches and the b-type absorption lines encompass the Ka = 1 - 0, 2 - 1, 3 - 2, 4 - 3 and 5 - 4 rotational sub-bands. The rotational constants and all quartic and sextic centrifugal distortion constants have been determined for each rotamer using Watson's reduced Hamiltonian. In addition to the measured line positions the frequencies of some selected low-J transitions, not observed in this work but of potential astrophysical interest, have been listed as an aid in the interstellar search for monothioformic acid.

Molecular Rotational Resonance Spectroscopy

1969 ◽  
Vol 23 (6) ◽  
pp. 575-581 ◽  
Author(s):  
Stuart Armstrong
Keyword(s):  
Molecular Structure ◽  
The Other ◽  
Resonance Spectroscopy ◽  
Rotational Resonance ◽  
Large Molecules ◽  
Intensity Measurements ◽  
Review Articles ◽  
Structure Determinations

A number of recent review articles have summarized the application of Molecular Rotational Resonance (MRR) spectroscopy to the area of molecular structure determinations and described how these applications have applied to chemistry. This article will briefly review this established area of MRR spectroscopy and describe two developments that offer the promise of expanding the applicability of MRR spectroscopy. The first development was the observation that some large molecules (by MRR standards) give a series of relatively intense, equally spaced bands that can be quickly recorded and assigned. The other development has been in the theory, procedures, and instrumentation required for accurate intensity measurements. These two developments, examples of each, and the implication of each for use by chemists, as well as molecular structure determinations, will be discussed. Spectrometers that are being used for studies in this established area and the two newer areas will be described in the Appendix.

14N-and D-Hyperfine Structure in the Rotational Spectrum of Pyrrolidine

1989 ◽  
Vol 44 (9) ◽  
pp. 837-840
Author(s):  
H. Ehrlichmann ◽  
J.-U. Grabow ◽  
H. Dreizler
Keyword(s):  
Fourier Transform ◽  
Hyperfine Structure ◽  
Fourier Transform Spectroscopy ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Rotational Spectra

Abstract We present an analysis of the rotational spectra of the normal and the N-deuterated pyrrolidine measured by microwave Fourier transform spectroscopy. The quartic centrifugal distortion con­ stants and the 14N coupling constants have been determined with higher accuracy. In addition the D hyperfine structure could be analyzed.

Rotational Spectra of Phosphorus Monosulfide up to 1 THz

1999 ◽  
Vol 54 (2) ◽  
pp. 137-145
Author(s):  
H. Klein ◽  
E. Klisch ◽  
G. Winnewisser
Keyword(s):  
Submillimeter Wave ◽  
Rotational Spectrum ◽  
Data Set ◽  
Rotational Spectra ◽  
Quantum Numbers ◽  
Hyperfine Constants ◽  
Vibrational Ground State ◽  
Structure Constants ◽  
First Time ◽  
Rotation Constant

Abstract The submillimeter-wave rotational spectrum of the PS radical in the electronic and vibrational ground state (X2 ΠI/2 , X2Π3/2) was recorded with the Cologne terahertz spectrometer in the fre-quency region between 540 GHz and 1.07 THz, covering rotational quantum numbers from J = 30.5 to 60.5. The PS radical has been produced by discharging PSCl3 buffered with Ar. For all transitions the Λ-doubling was resolved for both the 2ΠI/2 and 2Π3/2 states. For some transitions with ΔF = 0 the hyperfine structure (hfs) caused by the P-atom could partially be resolved even for rather high J values. Analysis of the complete rotational data set of PS allows the derivation of a full set of molecular parameters, including the rotational constants B, D, H, the fine-structure constants A,γ , Dγ , the parameters for the Λ-doubling p, Dp , q, and the magnetic hyperfine constants a, b, c, d, CI. All parameters have been determined, whereby a, c, and the nuclear spin rotation-constant CI were obtained for the first time.

Rotational Spectrum of Aminoborane: Centrifugal Distortion Constants and Boron and Nitrogen Hyperfine Structure

1991 ◽  
Vol 46 (9) ◽  
pp. 770-776 ◽  
Author(s):  
Kirsten Vormann ◽  
Helmut Dreizler ◽  
Jens Doose ◽  
Antonio Guarnieri
Keyword(s):  
Hyperfine Structure ◽  
Spin Rotation ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Rotational Spectra ◽  
Quadrupole Coupling ◽  
Wave Region ◽  
Nuclear Quadrupole ◽  
Centrifugal Distortion Constants

AbstractThe boron and nitrogen hyperfine structure in the rotational spectra of two aminoborane isotopomers, 11 BH2NH2 and 10BH2NH2, has been investigated and the quadrupole coupling constants of boron 10B, 11B and nitrogen 14N have been determined. We get the following results for the nuclear quadrupole coupling constants: χaa(11B) = -1.684 (14) MHz, χbb(11B) = -2.212 (11) MHz, χcc(11B) = 3.896(11) MHz, χaa(10B) = -3.481 (11) MHz, χbb(10B) = -4.623 (14) MHz, χCC(10B) = 8.104 (14) MHz and xaa(14N) = 0.095 (9) MHz, χbb(14N) = 2.091 (8) MHz, χcf4 (14N)=-2.186 (8) MHz. These nitrogen quadrupole coupling constants are those of the 11BH2 NH2 isotopomer. Additionally we were able to determine two out of the three spin rotation coupling constants caa, cbb, and ccc of boron, caa(11 B = 55.2 (26) kHz, cbb(11B) = 6.62 (36) kHz, caa (10B) = 15.26 (69) kHz and cbb(10B) = 4.94 (70) kHz. The spin rotation coupling constants ccc had to be fixed to zero in both cases. Furthermore we measured the rotational spectra in the mm-wave region to determine all quartic and several sextic centrifugal distortion constants according to Watson's A and S reduction

Determination of a High Barrier Hindering Internal Rotation from the Ground State Spectrum. The Methylbarrier of 1-Butyne

1985 ◽  
Vol 40 (3) ◽  
pp. 263-266 ◽  
Author(s):  
G. Bestmann ◽  
H. Dreizler
Keyword(s):  
Internal Rotation ◽  
Ground State ◽  
Rotational Spectrum ◽  
Rotational Spectra

With 1-butyne a series of barrier determinations from rotational spectra in the torsional ground state of ethyl compounds was continued. The barrier is different to the value from an analysis of the rotational spectrum of the first torsional state.

ab initio Calculation of 33S Quadrupole Coupling Constants. Reanalysis of the 33S Hyperfine Structure in the Rotational Spectrum of Thiirane

1997 ◽  
Vol 52 (4) ◽  
pp. 297-305 ◽  
Author(s):  
Barbara Kirchner ◽  
Hanspeter Huber ◽  
Gerold Steinebrunner ◽  
Helmut Dreizler ◽  
Jens-Uwe Grabow ◽  
...  
Keyword(s):  
Ab Initio Calculation ◽  
Experimental Information ◽  
Coupling Constants ◽  
Basis Sets ◽  
Rotational Spectrum ◽  
Rotational Spectra ◽  
Coupling Tensor ◽  
Quadrupole Coupling ◽  
Local Quality ◽  
Nuclear Quadrupole

Abstract We present quantum chemical calculations on the MP4(SDQ) level with basis sets of high local quality to determine the nuclear quadrupole coupling tensor of 33S in a series of molecules, which were investigated up to now by microwave spectroscopy. The analysis of the nuclear quadrupole coupling in the rotational spectra provided experimental information on the tensors. As an example for such an analysis, improved values for thiirane, C2H433S, are given: χaa = - 32.9425(78) MHz, χbb = -16.402(14) MHz, χcc = 49.345(14) MHz.

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