Proton magnetic shielding tensors from spin-rotation measurements on H2CO and NH3

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Abstract

The spin-rotation tensor for H2CO was obtained from very high resolution beam maser measurements of rotational transitions. Spin-rotation tensor elements are Maa = -4.12 ± 0.36 kHz, Mbb = 2.45 ± 0.32 kHz, and Mcc = -2.10 ± 0.34 KHz in the principal axis system. These results are combined with previous molecular orbital calculations of diamagnetic shielding to obtain total absolute shielding tensor elements of σaa = 15.9, σbb = 40.7, and σcc = -1.7 ppm and an average shielding of 18.3 ppm with uncertainties of ±2 ppm or better. A similar analysis is carried out for NH3. Spin-rotation tensors and shielding tensors are given for proton and nitrogen sites with estimated accuracy better than 1 ppm. For NH3 σzz(H) = 26.5 ppm and σ(H) = 31.2 ppm. The absolute shielding scale is discussed.

Original languageEnglish (US)
Pages (from-to)5704-5707
Number of pages4
JournalJournal of the American Chemical Society
Volume97
Issue number20
StatePublished - 1975

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Magnetic shielding
Shielding
Tensors
Protons
Uncertainty
Lasers
Masers
Nitrogen
Orbital calculations
Molecular orbitals

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Proton magnetic shielding tensors from spin-rotation measurements on H2CO and NH3. / Kukolich, Stephen G.

In: Journal of the American Chemical Society, Vol. 97, No. 20, 1975, p. 5704-5707.

Research output: Contribution to journalArticle

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abstract = "The spin-rotation tensor for H2CO was obtained from very high resolution beam maser measurements of rotational transitions. Spin-rotation tensor elements are Maa = -4.12 ± 0.36 kHz, Mbb = 2.45 ± 0.32 kHz, and Mcc = -2.10 ± 0.34 KHz in the principal axis system. These results are combined with previous molecular orbital calculations of diamagnetic shielding to obtain total absolute shielding tensor elements of σaa = 15.9, σbb = 40.7, and σcc = -1.7 ppm and an average shielding of 18.3 ppm with uncertainties of ±2 ppm or better. A similar analysis is carried out for NH3. Spin-rotation tensors and shielding tensors are given for proton and nitrogen sites with estimated accuracy better than 1 ppm. For NH3 σzz(H) = 26.5 ppm and σ(H) = 31.2 ppm. The absolute shielding scale is discussed.",
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AB - The spin-rotation tensor for H2CO was obtained from very high resolution beam maser measurements of rotational transitions. Spin-rotation tensor elements are Maa = -4.12 ± 0.36 kHz, Mbb = 2.45 ± 0.32 kHz, and Mcc = -2.10 ± 0.34 KHz in the principal axis system. These results are combined with previous molecular orbital calculations of diamagnetic shielding to obtain total absolute shielding tensor elements of σaa = 15.9, σbb = 40.7, and σcc = -1.7 ppm and an average shielding of 18.3 ppm with uncertainties of ±2 ppm or better. A similar analysis is carried out for NH3. Spin-rotation tensors and shielding tensors are given for proton and nitrogen sites with estimated accuracy better than 1 ppm. For NH3 σzz(H) = 26.5 ppm and σ(H) = 31.2 ppm. The absolute shielding scale is discussed.

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