Highly conducting perylene radical salts

Temperature dependent dc and microwave conductivity data together with EPR and optical reflectance measurements on the "mixed" system (pe)2(ASF6)0,75(PF6)0,35 times 0,85 CH2Cl2 are described. The data prove metallic behaviour of this organic solid down to 200 K

Spectral reflectance of the one-dimensional organic metals (perylene)2(PF6)1.1 × 0.8CH2Cl2 and (perylene)2(AsF6)1.1 × 0.7CH2Cl2

We report on the optical reflectance of (perylene)2(PF6)1.1 × 0.8CH2Cl2 and (perylene)2(AsF6)1.1 × 0.7CH2Cl2 single crystals in the energy range from 0.25 to 4 eV. For light polarized perpendicular to the molecular stacks the crystals exhibit the optical behaviour of an insulating molecular crystals, whereas for light polarized parallel to the stacks a pronounced plasma edge at hω=0,9eV image is observed. The experimental data were analyzed by a Lorentz-Drude model in order to determine the electrical conductivity, the carrier concentration, the effective mass, the collision time, the band width, and the Fermi vector of the crystals

Comparative optical investigations on the one-dimensional organic metals (perylene)2(PF6)1.1x0.8CH2Cl2, (pyrene)12(SbF6)7 and fluoranthene)2(AsF6)0.2(PF6)0.8

The reflectance spectra of different radical cation salts of the type (arene)2XF6 are reported (X=P, As, Sb). For light polarised perpendicular to the molecular stacks, the crystals exhibit the optical behaviour of an insulating molecular crystal, whereas for light polarised parallel to the stacks a pronounced plasma edge is observed. Compared to other organic metals the crystals show remarkably high values of the plasma energy. Because the concentration of the free carriers is obtained from the charge transfer between the radical cations and the inorganic counter ions, the effective mass of the free carriers may be calculated from the plasma frequency. The analysis of the reflectance data by a Lorentz-Drude model yields as well the values of the mean collition time, the electrical conductivity, and the bandwith

Plasma reflectance of the one-dimensional organic metals of the type (arene)2XF6(arene=perylene, pyrene or fluoranthene &#59; X=P, As, Sb)

We have investigated the spectral position and the form of the plasma edge of different radical cation salts of the type (arene)zXF, independence of the type of the organic donor molecule, and of the charge transfer between donor and acceptor molecules

PET Imaging in Altered States of Consciousness: Coma, Sleep, and Hypnosis

peer reviewedPositron emission tomography (PET) allows studies of cerebral metabolism and blood flow and has been widely used to investigate physiological mechanisms underlying altered states of consciousness. Consciousness is characterized by two components: wakefulness and awareness. In this chapter, we review the current literature on brain metabolism during pathological loss of consciousness (vegetative/unresponsive or minimally conscious states), sleep (in healthy subjects and in patients with insomnia), and under hypnosis. By identifying brain areas specifically involved in conscious processing, these studies have contributed to our understanding of the underlying physiology of consciousness. The precuneal and cingulate cortices, for example, seem to be key areas for maintaining conscious awareness. FDG-PET further allowed the identification of the minimal energetic requirement for conscious awareness in this population, which corresponds to 42% of normal cortical activity. Up to now, it is the most accurate neuroimaging tool regarding the diagnosis of patients with disorders of consciousness. In the future, its use as part of multimodal assessment could improve diagnosis and prognosis in this challenging population. In sleep, a greater activity of the precuneus/posterior cingulate cortex and the fronto-parietal areas during non rapid eye movement sleep also seems to play a role in disorders such as insomnia. Other areas such as the hypothalamus, amygdala, or temporo-occipital cortex seem to play a role in different states such as rapid eye movement sleep and hypnosis. PET studies permit a better comprehension of the neural correlates of consciousness and to identify the implication of specific neural areas and networks in altered states of consciousness in post-comatose patients, sleep and induced hypnosis