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We have developed a scanning magnetic microscope (SMM) with 25 µm resolution in spatial position for the magnetic features of room temperature objects. The microscope consists of a high-temperature superconductor (HTS) dc SQUID sensor, suspended in vacuum with a self-adjusting standoff, close spaced liquid nitrogen Dewar, X -Y scanning stage and a computer control system. The HTS SQUIDs were optimized for better spatial and field resolutions for operation at liquid nitrogen temperature. Measured inside a magnetic shield, the 10 pT Hz −1/2 typical noise of the SQUIDs is white down to frequencies of about 10 Hz, increasing up to about 20 pT Hz −1/2 at 1 Hz. The microscope is mounted on actively damped platforms, which negate vibrations from the environment as well as damping internal stepper motor noises. A high-resolution video telescope and a 1 µm precision z-axis positioning system allow a close positioning of the sample under the sensor. The ability of the sensors to operate in unshielded environmental conditions with magnetic fields up to about 15 G allowed us to perform 2D mapping of the local ac and dc susceptibility of the objects.

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Synthesis and Properties of Copper and Nickel Complexes of the General Formula (B11H11)2Mn-.Crystal Structure of ((n-Bu)4N)3(Cu(B11H11)2).-The anions Cu(B11H11)3-2 and Ni(B11H12)4-2 are prepared by reaction of Me3NH(B11H14) in aqueous NaOH with CuO or NiCl2, resp., and precipitated as Bu4N+ and Me4N+ salts in the case of the Cu complex and as Cs+ and Ph3PMe+ salts in the case of the Ni complex. The salts are characterized by the 11B-and 1H NMR spectra. According to the XRD data, ((Bu)4N)3(Cu(B11H11)2) crystallizes in the orthorhombic space group Pcnb with Z = 8. The anion represents a symmetrically bonded closo structure expected for a formal Cu(5+) (d6) ion η5-bonded to the open face of two B11H4-11 ligands. -(KESTER, J. G.; KELLER, D.; HUFFMAN, J. C.; BENEFIEL, M. A.; GEIGER, W. E. JUN.; ATWOOD, C.; SIEDLE, A. R.; KORBA, G. A.; TODD, L. J.; Inorg. Chem. 33 (1994) 24, 5438-5442; Dep. Chem., Indiana Univ., Bloomington, IN 47405-4001, USA; EN)