1H-ENDOR investigations on gamma-irradiated betaine calcium chloride dihydrate at room temperature

The ENDOR technique is applied to study the structure of the free radical N(CH₃)₃, found in the high temperature phase in the incommensurate crystal BCCD after γ-irradiation. The radical possesses a planar structure with strong deviation from the C₃ symmetry. The hybridization of the nitrogen atom is sp². Each of the three methyl groups exhibits a single ENDOR line, indicating the rotation of groups at room temperature. The deviation of the¹H hyperfine tensors of the methyl groups from axial symmetry is not a hint as to a hindered rotation of the groups. This is predicted by the C₂ symmetry of the system consisting of a π orbital and a rotating CH₃ group.     

Offset in CMOS magnetotransistors. II. Reduction

For pt.I see ibid., vol.48, no.9, pp.1945-53 (2001). Offset reduction principles for complementary metal oxide semiconductor (CMOS) magnetotransistors (MTs) are discussed and several approaches are examined experimentally. Special emphasis is put on addressing the MT offset causes previously identified as most critical. Contributions from metal contact misalignment are suppressed by an improved emitter shape and metal contact position as well as by enhanced process control. Implantation angle effects are avoided by an orthogonal implant or are corrected for with the knowledge of the actual implant direction. Small scale effects from, for example, doping inhomogeneities or emitter-collector spacing mismatch are averaged out along an increased device edge length or in arrays of MTs. Emitter guard misalignment in suppressed-sidewall-injection-MTs (SSIMTs) is avoided by self-aligning the guard with poly-silicon mashing, MTs with average absolute values of offset below 0.14% between -40°C and +140°C are achieved. These offsets are equivalent to a magnetic induction below 4 mT at room temperature     

Die ar?ometrische Analyse des Bieres

Ohne Zusammenfassung     

Synthesis and immobilization of molecular switches onto titaniumdioxide nanowires

The precursor [Fe^III(L)Cl (L = N,N′-bis(2′-hydroxy-3′-methyl-benzyliden)-1,7-diamino-4-azaheptane) is combined with [Mo(CN)₈]^4? yields a star shaped nona-nuclear cluster, [Mo^IV{(CN)Fe^III(L)}₈]Cl₄. This Fe₈Mo molecule is a high-spin system at room temperature. On cooling to 20 K some of the iron(III) centres in the molybdenum(IV)-star switch to the low-spin state as proven by Mössbauer spectroscopy. This molecule was deposited on TiO₂ nanowires by electrostatic interactions between the cluster cations and the surface functionalized titanium oxide nanowire. The synthesis and surface binding of the multistable molecular switch was demonstrated using IR and UV–Vis spectroscopy (high-resolution) transmission electron microscopy ((HR)TEM) and Mössbauer spectroscopy. High- and low-temperature Mössbauer spectra indicate that the spin state transition of the free cluster molecules is preserved after surface binding. The above results emphasize the possibility of fabricating molecule-based low-dimensional structures by using traditional bottom-up approaches based on the electrostatic interaction between the cluster cations and polymer functionalized nanowires. These results can be generalized for the application to both charged and non-charged molecules.