Separation and conversion of nuclear spin isomers of ethylene

Chapovsky, P. L.; Cosléou, J.; Herlemont, F.; Khelkhal, M.; Legrand, J.

doi:10.1016/s0009-2614(00)00445-0

Cited by 32 publications

(26 citation statements)

References 14 publications

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“…However, direct imido analogs of the uranyl ion have remained elusive despite a great deal of effort toward their synthesis. For instance, Denning and co-workers were able to isolate the phosphorane-iminato (UNPR 3 ) and sulfilimine (UNSR 2 ) substituted analogs of uranyl, which are heteroatom approximations to the imido ligand (7)(8)(9). Burns and co-workers were able to synthesize Cp* 2 U(NR) 2 (where R was either Ph or adamantyl and Cp* was C 5 Me 5 ), but with imido groups in a cis configuration (10,11).…”

Section: Separation and Conversion Dynamics Of Four Nuclear Spin Isommentioning

confidence: 99%

Separation and Conversion Dynamics of Four Nuclear Spin Isomers of Ethylene

Sun

Takagi

Matsushima

2005

Science

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time span simulated ( fig. S6 and table S8). These results, combined with the lack of resolution within superclades of the metazoan tree, argue against models of metazoan radiation in which the temporal window of diversification is much larger (48 Molecules with three or more nuclei of nonzero spin exist as discrete spin isomers whose interconversion in the gas phase is generally considered improbable. We have studied the interconversion process in ethylene by creating a sample depleted in the B 2u nuclear spin isomer. The separation was achieved through spatial drift of this isomer induced by resonant absorption of narrowband infrared light. Evolution of the depleted sample revealed conversion between B 2u and B 3u isomers at a rate linearly proportional to pressure, with a rate constant of 5.5 (T0.8) Â 10 j4 s j1 torr j1 . However, almost no change was observed in the A g isomer populations. The results suggest a spin conversion mechanism in C 2 H 4 via quantum relaxation within the same inversion symmetry.

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Section: Separation and Conversion Dynamics Of Four Nuclear Spin Isommentioning

confidence: 99%

Separation and Conversion Dynamics of Four Nuclear Spin Isomers of Ethylene

Sun

Takagi

Matsushima

2005

Science

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“…The conversion rate in ethylene ( 13 CCH 4 ) is equal to (5.2 ± 0.8) · 10 −4 s −1 /Torr [13]. In this molecule too the quantum relaxation is the leading process [8].…”

Section: Direct and Indirect Conversion Mechanismsmentioning

confidence: 99%

Nuclear spin conversion in formaldehyde

Chapovsky¹

2001

Journal of Molecular Structure

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Theoretical model of the nuclear spin conversion in formaldehyde (H 2 CO) has been developed. The conversion is governed by the intramolecular spinrotation mixing of molecular ortho and para states. The rate of conversion has been found equal γ/P = 1.4 · 10 −4 s −1 /Torr. Temperature dependence of the spin conversion has been predicted to be weak in the wide temperature range T = 200 − 900 K.

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“…[9] One of the most efficient methods is the lightinduced-drift (LID) approach, [9,10] which was successfully used to separate the NSIMs of CH 3 F and 13 CH 3 F, [10,11] as well as ethylene [12] and 13 C-labeled ethylene. [13] Separation in cold molecular beams was used recently to produce spin-polarized focused beams of NSIMs for water and methane. [14] Unfortunately, all production approaches for NSIMs demonstrated so far provide enriched NSIMs in very limited quantities, which are insufficient for many scientific and practical applications.…”

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Nuclear Spin Isomers of Ethylene: Enrichment by Chemical Synthesis and Application for NMR Signal Enhancement

et al. 2013

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Taking CH2CH2 for a spin: Enrichment of the nuclear spin isomers of ethylene was achieved by a catalytic reaction of acetylene with parahydrogen (see scheme). The spin isomers were used for NMR signal enhancement, both with and without subjecting them to a chemical reaction. The interconversion times of the nuclear spin isomers were evaluated at ambient pressure, thus revealing extremely long‐lived spin states with lifetimes of (1000±400) s.

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Separation and conversion of nuclear spin isomers of ethylene

Cited by 32 publications

References 14 publications

Separation and Conversion Dynamics of Four Nuclear Spin Isomers of Ethylene

Separation and Conversion Dynamics of Four Nuclear Spin Isomers of Ethylene

Nuclear spin conversion in formaldehyde

Nuclear Spin Isomers of Ethylene: Enrichment by Chemical Synthesis and Application for NMR Signal Enhancement

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