scholarly journals Measurements of Properties of Antihydrogen

2018 ◽  
Vol 46 ◽  
pp. 1860069
Author(s):  
Art Olin ◽  
Keyword(s):  
Hyperfine Splitting ◽  
Resonance Spectrum ◽  
Theoretical Framework ◽  
Fundamental Symmetries ◽  
Antihydrogen Atom ◽  
A Value ◽  
Spin Resonance ◽  
The Masses ◽  
Bounded Below ◽  
First Time

The ALPHA project at the CERN AD is testing fundamental symmetries between matter and antimatter using trapped antihydrogen atoms. The spectrum of the antihydrogen atom may be compared to ordinary hydrogen where it has been measured very precisely. CPT conservation, which underpins our current theoretical framework, requires equality of the masses and charges of matter and its antimatter partners, so antihydrogen spectroscopy presents a path to precision CPT tests. I will discuss the techniques used by ALPHA to trap more than 8000 antihydrogen atoms in 2016, and interrogate them for 600s. The 1S-2S transition in antihydrogen has been observed for the first time, and it agrees with its hydrogen counterpart within an uncertainty of 400 kHz or 0.2 ppb. The charge of the antihydrogen atom has been bounded below [Formula: see text]. A value of 1420.4 0.5MHz for the hyperfine splitting has been obtained from observation of the positron spin resonance spectrum.

Radical cations of some substituted pyrenes

1970 ◽  
Vol 48 (13) ◽  
pp. 1996-1999 ◽  
Author(s):  
J. T. Cooper
Keyword(s):  
Electron Spin Resonance ◽  
Sulfur Dioxide ◽  
Chlorine Atom ◽  
Electron Spin ◽  
Hyperfine Splitting ◽  
Boron Trifluoride ◽  
Radical Cations ◽  
Molecular Orbital Calculations ◽  
Spin Resonance ◽  
First Time

The electron spin resonance spectra of several substituted pyrene cations, produced by oxidation with boron trifluoride in sulfur dioxide, are reported. The spectra are analyzed and the splitting constants given. With 4-chloropyrene, hyperfine splitting is observed due to the chlorine atom, for the first time in such a species. Molecular orbital calculations (Hückel and McLachlan) are presented for three of the compounds studied.

scholarly journals THE NUCLEAR SPIN RESONANCE SPECTRUM OF Al27 IN SPODUMENE

1958 ◽  
Vol 36 (10) ◽  
pp. 1295-1307 ◽  
Author(s):  
L. B. Robinson
Keyword(s):  
Nuclear Spin ◽  
Resonance Spectrum ◽  
Companion Paper ◽  
Quadrupole Interactions ◽  
Resonance Frequencies ◽  
Spin Resonance ◽  
Theoretical Predictions ◽  
Induction Type ◽  
First Time ◽  
Good Agreement

An experimental study has been made of the nuclear spin resonance spectrum of Al27 in a single crystal of spodumene (LiAl(SiO3)2) over a range of external magnetic field H0 wide enough [Formula: see text] to bridge for the first time the gap between pure quadrupole spectra (R = 0) and Zeeman spectra slightly perturbed by quadrupole interactions [Formula: see text]. Experimental results on the resonance frequencies and relative signal amplitudes obtained with an induction type of nuclear resonance spectrometer are described, and are found to be in good agreement with the theoretical predictions given in the preceding companion paper.

Magnetic interactions in the Mn(II)/cyanide system

1970 ◽  
Vol 48 (7) ◽  
pp. 1073-1077 ◽  
Author(s):  
E. Rotlevi. ◽  
D. R. Eaton
Keyword(s):  
Magnetic Properties ◽  
Hyperfine Splitting ◽  
Resonance Spectrum ◽  
Exchange Process ◽  
Magnetic Interactions ◽  
Rate Process ◽  
Manganese Ions ◽  
Aqueous Methanol ◽  
Dipole Interactions ◽  
Spin Resonance

A well-resolved electron spin resonance spectrum has been observed from frozen aqueous, methanol/water mixtures, and acetonitrile/water mixtures of potassium manganocyanide. Hyperfine splitting from at least two manganese atoms is present. The sharpness of the lines indicates that a rate process capable of averaging the anisotropic dipole–dipole interactions is operative. These results are discussed in terms of the known chemical and magnetic properties of Mn(II)/cyanide systems. It is suggested that an exchange process involving low-spin and high-spin manganese ions in the same molecule occurs.

Organic and biological spectrochemical studies. XXIV. Electron spin resonance studies on the hydroquinone cation radical

1967 ◽  
Vol 45 (3) ◽  
pp. 267-273 ◽  
Author(s):  
A. B. Barabas ◽  
W. F. Forbes ◽  
P. D. Sullivan
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin Resonance Spectrum ◽  
Potential Barrier ◽  
Electron Spin ◽  
Resonance Spectrum ◽  
Cation Radical ◽  
Aluminium Chloride ◽  
Kcal Mole ◽  
A Value ◽  
Spin Resonance

The electron spin resonance spectrum of hydroquinone in aluminium chloride – nitromethane is interpreted in terms of cis–trans isomerism. Calculations based on the variation of the spectrum with temperature lead to a value for the potential barrier to rotation about the C—O bond of ca. 10 kcal/mole. The value of the constant QOH is discussed.

scholarly journals Optimization of Lignin Extraction Variables by Response Surface Methodology from Pine Saw Dust, and Quantification of Major Structural Units in Isolated Lignin Fraction

2021 ◽  
Vol 11 (4) ◽  
pp. 1739
Author(s):  
Muhammad Ajaz Ahmed ◽  
Jae Hoon Lee ◽  
Joon Weon Choi
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Quantum Coherence ◽  
Resonance Spectrum ◽  
Quadratic Model ◽  
Molecular Weights ◽  
Solids Loading ◽  
A Value ◽  
Lignin Extraction ◽  
Lignin Fraction

A synergistic combination of dioxane, acetic acid, and HCl was investigated for lignin extraction from pine wood biomass. After initial screening of reagent combination, response surface methodology (RSM) was used to optimize the lignin yield with respect to the variables of time 24–72 h, solids loading 5–15%, and catalyst dose 5–15 mL. A quadratic model predicted 8.33% of the lignin yield, and it was further confirmed experimentally and through the analysis of variance (ANOVA). Lignin at optimum combination exhibited features in terms of derivatization followed by reductive cleavage (DFRC) with a value of (305 µmol/gm), average molecular weights of 4358 and polydispersity of 1.65, and 2D heteronuclear single quantum coherence nuclear magnetic resonance spectrum (2D-HSQC NMR) analysis showing relative β-O-4 linkages (37.80%). From here it can be suggested that this fractionation can be one option for high quality lignin extraction from lignocellulosic biomass.

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