%0 Journal Article %J Journal of Chemical Physics %D 1999 %T NMR study of InP quantum dots: Surface structure and size effects %A Tomaselli, M. %A Yarger, J. L. %A Bruchez, M. %A Havlin, R. H. %A deGraw, D. %A Pines, A. %A Alivisatos, A. P. %K clusters %X

We report the results of P-31 NMR measurements on trioctylphosphine oxide (TOPO) passivated InP quantum dots. The spectra show distinct surface-capping sites, implying a manifold of crystal-ligand bonding configurations. Two In P-31 surface components are resolved and related to different electronic surroundings. With decreasing particle size the In P-31 core resonance reveals an increasing upfield chemical shift related to the overall size dependence of the InP electronic structure. (C) 1999 American Institute of Physics. [S0021-9606(99)70718-X].

%B Journal of Chemical Physics %V 110 %P 8861-8864 %8 May 8 %@ 0021-9606 %G English %U ://WOS:000080073200002 %N 18 %M WOS:000080073200002 %! NMR study of InP quantum dots: Surface structure and size effects %R Doi 10.1063/1.478858 %0 Journal Article %J Applied Physics Letters %D 1998 %T Low field magnetic resonance images of polarized noble gases obtained with a dc superconducting quantum interference device %A Augustine, M. P. %A Wong-Foy, A. %A Yarger, J. L. %A Tomaselli, M. %A Pines, A. %A TonThat, D. M. %A Clarke, J. %K mri %X

Using a low transition temperature superconducting quantum interference device as a detector, we have obtained magnetic resonance images of laser-polarized He-3 gas and solid Xe-129 at 4.2 K in magnetic fields as low as 0.54 mT (He-3) and 1 mT (Xe-129), corresponding to Larmor frequencies of 17.6 and 11.8 kHz, respectively. The experimental resolution of the images is similar to 500 mu m for He-3 ill the gas phase and similar to 950 mu m for Xe-129 in the solid state. (C) 1998 American Institute of Physics.

%B Applied Physics Letters %V 72 %P 1908-1910 %8 Apr 13 %@ 0003-6951 %G English %U ://WOS:000073054300038 %N 15 %M WOS:000073054300038 %! Low field magnetic resonance images of polarized noble gases obtained with a dc superconducting quantum interference device %R Doi 10.1063/1.121223 %0 Journal Article %J Physical Review B %D 1998 %T Scalar and anisotropic J interactions in undoped InP: A triple-resonance NMR study %A Tomaselli, M. %A deGraw, D. %A Yarger, J. L. %A Augustine, M. P. %A Pines, A. %K solids %X

The heteronuclear J-coupling tensor between nearest neighbor P-31 and In-113 spins in undoped InP is investigated by means of In-113-->P-31 polarization transfer under rapid magic angle spinning (MAS). The scalar contribution can be measured directly and is found to have the value \J(iso)(P-31-In-113,In-115)\ = (225+/-10) Hz. The principal value of the traceless anisotropic J-coupling tensor (pseudodipolar coupling) is determined to be J(aniso)(P-31-In-113,In-115)= 2/3[J(parallel to)(P-31-In-113,In-115)-J(perpendicular to)(P-31-In-113,In-115)] = (813+/-50) or (1733+/-50) Hz, assuming axial symmetry with the principal axis parallel to the In-P bond. Our values deviate from those reported previously [M. Engelsberg and R. E. Norberg, Phys. Rev. B 5, 3395 (1972)] [based on a moment analysis of the P-31 resonance \J(iso)(31P-In-113,In-115)\ = 350 Hz and J(aniso)(P-31-In-113,In-115) = 1273 Hz], but confirm the postulate that the nearest neighbor P-31-In-113,In-115 magnetic dipolar and pseudodipolar interactions are of the same order of magnitude and partially cancel each other.

%B Physical Review B %V 58 %P 8627-8633 %8 Oct 1 %@ 0163-1829 %G English %U ://WOS:000076232100075 %N 13 %M WOS:000076232100075 %! Scalar and anisotropic J interactions in undoped InP: A triple-resonance NMR study %R Doi 10.1103/Physrevb.58.8627