title: Dynamic nuclear polarization of nitrogen-15 in benzamide.
abstract: A 15N dynamic nuclear polarization (DNP) experiment is reported in which a 15N DNP enhancement factor of approximately 2.6 x 10(2) is obtained on free radical doped samples of 99% 15N labeled benzamide. The free radicals BDPA (1:1 complex of alpha, gamma-bisdiphenylene-beta-phenylallyl with benzene) and DPPH (2,2-Di(4-tert-octylphenyl)-1-picrylhydrazyl) are used as dopants and the spin relaxation effects of adding these dopants are studied by means of changes in proton and nitrogen T1 values of the samples. The combination in solids of a very low natural abundance, 0.37%, a small gyromagnetic ratio, and a long spin-lattice relaxation time for 15N nuclei create severe sensitivity problems that, in large part, are ameliorated by the signal enhancement observed in the 15N DNP experiment on samples containing free electrons.
authors.affiliation: Laboratory of Magnetic Resonance, and Atomic and Molecular Physics, Wuhan Institute of Physics, Chinese Academy of Sciences, People's Republic of China.
authors.forename: J Z
authors.initials: JZ
authors.lastname: Hu
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: B
authors.initials: B
authors.lastname: Yang
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Qiu
authors.forename: C
authors.initials: C
authors.lastname: Ye
authors.forename: M S
authors.initials: MS
authors.lastname: Solum
authors.forename: R A
authors.initials: RA
authors.lastname: Wind
authors.forename: R J
authors.initials: RJ
authors.lastname: Pugmire
authors.forename: D M
authors.initials: DM
authors.lastname: Grant
mesh_terms: D001549:Benzamides / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry; D001555:Benzene Derivatives / Q000737:chemistry; D015764:Bepridil / Q000031:analogs & derivatives / Q000737:chemistry; D001713:Biphenyl Compounds; D055590:Electromagnetic Phenomena; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D005609:Free Radicals / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D009584:Nitrogen / Q000737:chemistry*; D009587:Nitrogen Isotopes; D010851:Picrates; D011522:Protons
chemical_list: D001549:Benzamides; D001555:Benzene Derivatives; D001713:Biphenyl Compounds; D005609:Free Radicals; D009587:Nitrogen Isotopes; D010851:Picrates; D011522:Protons; C037689:benzamide; D015764:Bepridil; C004931:1,1-diphenyl-2-picrylhydrazyl; D001554:Benzene; D009584:Nitrogen