Nuclear Spin Conversion of H2, H2O, and CH4Interacting with Diamagnetic Insulators

Yamakawa, Koichiro; Fukutani, Katsuyuki

doi:10.7566/jpsj.89.051016

Cited by 5 publications

(5 citation statements)

References 144 publications

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“…The new non-magnetic conversion patterns that appeared in the past twenty years in the new materials investigated are particularly related and sensitive to the surface electronic structures [144,145]. Are they related to the local electric field strength and/or to its inhomogeneity and/or to the local density of charges?…”

Section: Conversion In Dielectric Insulatorsmentioning

confidence: 99%

“…Many experimental observations of the hydrogen nuclear spin isomers hav reported in the past decades, but seldom theoretical ones [142,143]. Apart from the lic conversion ones, new and numerous conversion effects were observed on amo or crystalline insulators, in semi-conductors, polymers and viscous organic liqui non-magnetic conversion mystery had started off again [127][128][129][130][131]144]. That secti deal with the fast conversion rates that had been measured in MOF and ASW sam low and very low temperatures, with characteristic times of the order of one o minutes, as related in Chapter 3.…”

Section: Conversion In Dielectric Insulatorsmentioning

confidence: 99%

“…The combination of hydrogen spin isomers mixtures in non-thermal proportions, together with "site-specific" spectroscopy, has brought important information on surfaces [5,6,144] and is also used to follow the transient states of chemical reactions [121]. In astrophysics, the ortho-para ratio (OPR) helps to date the formation of interstellar clouds [154].…”

Section: Memory and Datingmentioning

confidence: 99%

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Hydrogen Conversion in Nanocages

Ilisca

2021

Hydrogen

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Hydrogen molecules exist in the form of two distinct isomers that can be interconverted by physical catalysis. These ortho and para forms have different thermodynamical properties. Over the last century, the catalysts developed to convert hydrogen from one form to another, in laboratories and industries, were magnetic and the interpretations relied on magnetic dipolar interactions. The variety concentration of a sample and the conversion rates induced by a catalytic action were mostly measured by thermal methods related to the diffusion of the o-p reaction heat. At the turning of the new century, the nature of the studied catalysts and the type of measures and motivations completely changed. Catalysts investigated now are non-magnetic and new spectroscopic measurements have been developed. After a fast survey of the past studies, the review details the spectroscopic methods, emphasizing their originalities, performances and refinements: how Infra-Red measurements characterize the catalytic sites and follow the conversion in real-time, Ultra-Violet irradiations explore the electronic nature of the reaction and hyper-frequencies driving the nuclear spins. The new catalysts, metallic or insulating, are detailed to display the operating electronic structure. New electromagnetic mechanisms, involving energy and momenta transfers, are discovered providing a classification frame for the newly observed reactions.

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Section: Conversion In Dielectric Insulatorsmentioning

confidence: 99%

Section: Conversion In Dielectric Insulatorsmentioning

confidence: 99%

Section: Memory and Datingmentioning

confidence: 99%

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Hydrogen Conversion in Nanocages

Ilisca

2021

Hydrogen

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“…ird, water blocks the channel of methane molecules into the micropores. Due to the fact that the specific surface area of the pores is the main carrier of coal adsorption [41], water will form capillary resistance within the micropores of coal [42,43]. Especially when the pressure between the internal and the external environments of the pores is insufficient to overcome the capillary resistance, the methane molecules are prevented from entering the pores, thereby reducing the amount of adsorbed methane in coal [44].…”

Section: Initial Amount Of Desorbed Gasmentioning

confidence: 99%

Moisture Content on Methane Desorption Characteristics in Coal and Its Effect on Outburst Prediction

Cao

Wang

et al. 2021

Advances in Civil Engineering

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Coal and gas outburst is a dynamic phenomenon with violent eruptions of coal and gas from the working coal seam. It has been proved that rapid desorption within a short period is necessary for the occurrence of an outburst. Due to the limitation of the present test condition, gas desorption characterization in coal with different moisture content for the first several seconds (0–60 s) has not been researched sufficiently. In this study, initial desorption characterization of gas in coal with different moisture content is studied by experiments with methane. The most remarkable characteristic of the experimental setup is the application of a self-developed real-time data acquisition system with a time interval of about 10 ms, which achieves the goal of collecting enough pressure data for analysis and calculation. The data is used to study gas pressure variation and calculate the initial amount of desorbed gas and index (ΔP) of initial velocity diffusion of coal gas. From the experimental results, the new proof has been found to verify that coal with lower moisture content and methane outburst is more dangerous than coal with higher moisture content and outburst. The degree of coal and methane outburst is exponentially decaying with increasing moisture content.

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“…The o-p conversion is closely related to the quest for efficient ways of the H 2 storage ( Ilisca, 2021 ), and therefore is being investigated not only on surfaces but also inside solids ( Lavrov and Weber, 2002 ; Hiller et al, 2007 ; Peng et al, 2009 ) and nano-cages ( Carravetta et al, 2004 ; Carravetta et al, 2006 ; Carravetta et al, 2007 ). Stimulated by the development of the experimental investigations, several conversion mechanisms have been also proposed depending on the interacting materials ( Yamakawa and Fukutani, 2020 ): the Wigner model ( Wigner, 1933 ), where the proton spin interacts with the inhomogeneous magnetic field generated by localized paramagnetic ions; the electron-spin-induced conversion models categorized into the second- ( Ilisca, 1991 ) and third-order ( Ilisca and Ghiglieno, 2016 ) perturbation theories, where the virtual electron exchange or transfer between H 2 and a surface is involved along with the Fermi contact interaction between an electron and a proton in H 2 ; the electric-field-induced conversion model ( Sugimoto and Fukutani, 2011 ), where the Stark, spin-orbit, and Fermi-contact couplings mix the ortho and para states.…”

Section: Introductionmentioning

confidence: 99%

Fast ortho-to-para conversion of molecular hydrogen in chemisorption and matrix-isolation systems

Ueta,

Fukutani,

Yamakawa

2023

Front. Chem.

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Molecular hydrogen has two nuclear-spin modifications called ortho and para. Because of the symmetry restriction with respect to permutation of the two protons, the ortho and para isomers take only odd and even values of the rotational quantum number, respectively. The ortho-to-para conversion is promoted in condensed systems, to which the excess rotational energy and spin angular momentum are transferred. We review recent studies on fast ortho-to-para conversion of hydrogen in molecular chemisorption and matrix isolation systems, discussing the conversion mechanism as well as rotational-relaxation pathways.

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Nuclear Spin Conversion of H₂, H₂O, and CH₄Interacting with Diamagnetic Insulators

Cited by 5 publications

References 144 publications

Hydrogen Conversion in Nanocages

Hydrogen Conversion in Nanocages

Moisture Content on Methane Desorption Characteristics in Coal and Its Effect on Outburst Prediction

Fast ortho-to-para conversion of molecular hydrogen in chemisorption and matrix-isolation systems

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