The heats of combustion of 1-nitroadamantane (1), 2-nitroadamantane (2), 2,2-di-nitroadamantane (3) and 2-cyano-2-nitroadamantane (4) were measured by combustion calorimetry, and the heats of sublimation were derived from the temperature dependence of the vapour pressure measured in a flow system. The results for ΔHXXXc(c) and ΔHSub (in kJ mol−1, standard deviation in parentheses) are: 1, −5824.1 (±2.2) and 63.6 (±1.0); 2, −5841.0 (±2.2) and 58.0 (±2.3); 3, −5685.2 (±1.0) and 96.4 (±1.4); 4, −6238.4 (±1.5) and 70.0 (±1.9).
A comparison of the resulting heats of formation ΔHXXXf(g) (in kJ mol−1, standard deviation in parentheses) for 1 = −191.1 (± 2.4), 2 = −179.8 (±3.2), 3 = −154.3 (±1.7) and 4 = −21.0 (±2.5) reveals a destabilizing interaction of the geminal substituents in 3 and 4 amounting to 59 kJ mol−1 (nitro/nitro) and 33 kJ mol−1 (nitro/cyano) respectively. 相似文献
Binary mixed thin films of picene (C22H14, PIC) and pentacene (C22H14, PEN) consist of crystallites with a statistical occupation of the lattice sites by either PEN or PIC and unit cell parameters continuously changing with the mixing ratio. For high PIC ratios a PIC phase forms which corresponds to a limited intermixing of the two compounds. The growth behavior of these mixtures is investigated in situ and in real‐time using grazing incidence X‐ray diffraction. We observe a delayed phase separation in PIC‐rich blends, i.e. complete intermixing in the monolayer range and the nucleation of a pure PIC‐phase in addition to the intermixed phase starting from the second monolayer.
Growth scenario of picene‐rich pentacene‐picene blends. 相似文献
Magnetic polarization of Mo atoms in Co96Mo4 alloy film and Co/Mo multilayered structures has been studied by X‐ray magnetic circular dichroism. Samples with Mo spacers of two different thicknesses (0.9 nm and 1.8 nm) were investigated. Mo atoms receive a magnetic moment of ?0.21μB in the alloy. In the multilayer with the thinner Mo spacer (dMo = 0.9 nm) the magnetic moment is much smaller (?0.03μB). In both cases the measured induced moment at the Mo site is oriented antiparallel to the moment at the Co atoms. The presence of the induced moment in the Mo spacer coincides with antiferromagnetic coupling between the Co component slabs. In contrast, neither measurable induced moment at the Mo site nor interlayer coupling between the Co layers has been found for the multilayer with the thicker Mo spacer. Possible mechanisms of the coupling associated with the induced moment are discussed in detail. 相似文献