Rotation of laser beam polarization in acousto-optic devices

When a linear, polarized laser beam is passed through an acousto-optic device, the polarization direction of the outgoing beam is often different from that of the entering beam, and thus a rotation of the polarization angle takes place. This paper shows how the polarization rotation and the intensity can be calculated for different polarization angles. Experimental results obtained with a single crystal germanium frequency shifter in the 10.6 μm region agreed well with theory.     

Raman scattering in low stage compounds of graphite intercalated with AsF5, HNO3 and SbCl5

Raman measurements on low stage compounds of graphite intercalated with AsF₅, HNO₃ and SbCl₅ are reported. The spectrum of the stage 1 C₈AsF₅ acceptor compound is found to be in sharp contrast with that reported for the donor stage 1 C₈M(M=K, Rb, Cs) compounds. Whereas the stage 1 donor compounds have been found to exhibit a characteristic broad, asymmetric Breit-Wigner line shape, the spectrum of C₈AsF₅ contains a single Lorentzian line in this frequency region. Temperature studies of the bounding layer mode lineshape parameters in C₈AsF₅ showed no evidence of the order-disorder transition in the adjacent intercalate layer. The bounding layer mode frequencies of AsF₅, HNO₃ and SbCl₅ graphite are reported, but no intercalate layer modes were observed.     

Signal enhancement in carbon-filament atomic absorption spectrometry by metal—oxygen reactions

Investigations of signal enhancement in carbon-filament atomic absorption spectrometry are described. Several enhancements are shown to be due to preferential binding of the oxygen by the added interferent in the gas phase. This prevents the analyte atoms from reacting with the oxygen, thereby preserving or enhancing the atom concentration and thus the absorbance signal.     

C-axis thermoelectric transport in low stage SbCl5 graphite intercalation compounds

c-axis thermal conductivity, electrical resistivity and thermopower measurements performed on stages-2, 3 and 4 SbCl₅-graphite intercalation compounds in the temperature range 3 < T < 300 K are reported. Contrary to the electrical resistivity and thermopower data, the temperature variation of the thermal conductivity is qualitatively different from that previously observed on other intercalation compounds.     

Atomic arrangement of iodine atoms inside single-walled carbon nanotubes

We report atomic resolution Z-contrast scanning transmission electron microscopy images that reveal the incorporation of I atoms in the form of helical chains inside single-walled carbon nanotubes. Density functional calculations and topological considerations provide a consistent interpretation of the experimental data. Charge transfer between the nanotube walls and the I chains is associated with the intercalation.     

Determination of U(IV) and U(VI) by ion chromatography-inductively coupled plasma mass spectrometry and its application to kinetic studies

The ions normally formed by actinides in aqueous solutions by the oxidation states III-VI are M3-, M4+, MO2+ and MO2(+2), respectively. Oxidation state representatives such as Am3+, Th4+, NpO+ and UO+, which resist oxidation state changes, were used to investigate a method to separate the oxidised species (MO2 and MO2(2+)) from the reduced species (M3+ and M4+). With this method the hexavalent state of uranium could be separated from the tetravalent state of uranium in aqueous media in less than 8 min. Uranium concentrations down to 10(-9) M could be analysed without changing the redox composition during the separation. The oxidation kinetics of the tetravalent uranium for different hydrochloric acid concentrations was investigated. The measurements showed good agreement with values found in the literature, although the uranium concentrations were one million times lower.