A new form of P: The crystal structure of a fibrous type of red phosphorus was solved using single‐crystal X‐ray diffraction methods and transmission electron microscopy. It consists of double tubes (see picture) and is closely related to the structure of Hittorf's phosphorus. Density functional calculations confirm the experimental results.

Lehrbüchern der allgemeinen Chemie zufolge existieren drei Hauptmodifikationen des Elementes Phosphor, und zwar weißer, roter und schwarzer Phosphor, die sich erheblich in ihren chemischen und physikalischen Eigenschaften unterscheiden. Wird weißer Phosphor erhitzt oder Strahlung aus-

Structure D 2000Fibrous Red Phosphorus. -Fibrous red phosphorus is prepared from amorphous red phosphorus by sublimation with iodine (evacuated silica tubes, 590-570°C, several days). The samples are characterized by single crystal XRD and TEM and the previously assumed structure is confirmed. This form of red phosphorus crystallizes in the triclinic space group P1. The crystal structure consists of tubes with pentagonal cross section, which in turn are a regular sequence of three different building units. The subunits are cages of eight or nine P atoms and dumbbells of two P atoms. The fibrous type of crystalline red phosphorus shows strong structural resemblance to Hittorf's phosphorus. -(RUCK*, M.; HOPPE, D.; WAHL, B.; SIMON, P.; WANG, Y.; SEIFERT, G.; Angew. Chem., Int. Ed. 44 (2005) 46, 7616-7619; Inst. Anorg.

The cylindrical geometry of nanotubes dictates a strong anisotropy of their physical properties. In practice, the difficulty in extracting individual components of the elastic tensor has limited the available information to only very partial and indirect experimental data. Here, the interlayer shear (sliding) modulus (C 44 ) of single multiwalled WS 2 nanotubes was studied by atomic force microscopy bending tests. The observed value of 2 GPa agrees well with the value of 4 GPa obtained for density functional tight binding calculations for 2H-MoS 2 . This value of the shear modulus represents a much higher degree of anisotropy than that obtained for carbon nanotubes and enables assignment of the mode of shear deformation.