The infrared spectrum of the endohedral metallofullerene Li+ @ C60 is calculated. Vibrational and rotational motion of the charged inclusion leads to the emission and absorption of radiation. Our calculations assume t...
The infrared spectrum of the endohedral metallofullerene Li+ @ C60 is calculated. Vibrational and rotational motion of the charged inclusion leads to the emission and absorption of radiation. Our calculations assume this motion is governed by the intramolecular ''reflected Morse'' potential of Dunlap, Ballester and Schmidt. The predicted pure rotation band peaks near 40 cm-1. The fundamental vibration-rotation band at 350 cm-1 exhibits unusual band-head structure. Both bands are intense. The first overtone band at 700 cm-1 is also studied. Rotational structure is well resolved in all three bands;at room temperature, hot bands contribute significantly.
We compute the far-infrared absorption spectrum of the endohedral metallofullerene K+ @ C60. This arises from the vibrational and rotational motion of the potassium ion about its equilibrium position at the center of ...
We compute the far-infrared absorption spectrum of the endohedral metallofullerene K+ @ C60. This arises from the vibrational and rotational motion of the potassium ion about its equilibrium position at the center of the buckyball cage. The spectrum is quite unusual. Although the permanent dipole moment of the complex is zero, absorption is very intense. The spectrum contains a pure rotation band, which peaks near 55 cm-1 at 25-degrees-C. There is also a fundamental vibration-rotation band, consisting of a strong P-branch at 70 cm-1, overlapping the rotational band, and a much weaker R-branch at 180 cm-1. Line-spacing is strongly dependent on the rotational quantum number. Hot bands contribute significantly to the intensity. We include a discussion of dipolar shielding effects.
The electric modulus representation is used to display conductivity and dielectric relaxation occurring in poly(propylene glycol)-4000 (PPG) complexed with LiCF3SO3, as the ether oxygen to lithium (O:Li) ratio is vari...
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The electric modulus representation is used to display conductivity and dielectric relaxation occurring in poly(propylene glycol)-4000 (PPG) complexed with LiCF3SO3, as the ether oxygen to lithium (O:Li) ratio is varied from 300:1 to 12:1. The frequency range covered is 10 to 10(7) Hz. Results are obtained for temperatures above the glass transition temperature appropriate for each PPG-LiCF3SO3 complex. For O:M = 300:1, the conductivity peak and the alpha and alpha' relaxation are clearly resolved. As the concentration is increased, there is a coupling between the structural and the conductivity relaxations;the various peaks begin to overlap. The coupling is greatest for an O:Li ratio in the range 30:1 to 12:1, where the highest conductivity is measured. Below room temperature, the 30:1 complex has the highest conductivity, above room temperature the 12:1 complex has the highest. At any particular temperature there is a concentration above which the conductivity drops. This drop is due to reduced ion mobility resulting from a dramatic increase in viscosity to values above approximately 100 poise.
The various mechanisms giving rise to low-energy peak tailing in Si(Li) X-ray detectors are discussed. The Hypermet lineshape function is shown to be satisfactory in the energy range 4–15 keV. Stringent tests of the ...
The various mechanisms giving rise to low-energy peak tailing in Si(Li) X-ray detectors are discussed. The Hypermet lineshape function is shown to be satisfactory in the energy range 4–15 keV. Stringent tests of the X-ray relative intensity database used in PIXE, performed with detectors of accurately known lineshape, lend it strong support. Current measurements of the L subshell fluorescence and Coster-Kronig yields indicate that the latter may be systematically lower than theory.
Published theoretical L x-ray emission rates based upon a fixed atomic potential cover the atomic number range Z = 4 to 94. However, the presumably more accurate calculations employing different initial- and final-sta...
Published theoretical L x-ray emission rates based upon a fixed atomic potential cover the atomic number range Z = 4 to 94. However, the presumably more accurate calculations employing different initial- and final-state potentials have been done for only 21 values of Z . The ratio of these two rates for each electric dipole transition as a function of Z is fitted using polynomials in piece-wise fashion. The fixed-potential emission rates are then renormalized by these interpolated ratios to provide equivalent two-potential rates. The errors incurred are generally under 0.2%.
We reanalyse the published X-ray diffraction data on water with the object of deducing the isochoric temperature derivative of the structure factor of H 2 O at 4°C and 1 atm. These results are compared to the pub...
We reanalyse the published X-ray diffraction data on water with the object of deducing the isochoric temperature derivative of the structure factor of H 2 O at 4°C and 1 atm. These results are compared to the published molecular dynamics results for the MCY potential. Similar (published) neutron-diffraction results are discussed. The effect of “hydrogen-bond formation” on neutron and X-ray pair correlation functions is discussed qualitatively and quantitatively. The probable structural effects of non-additive forces are deduced from the behaviour of these derivatives, and some comments on quantum effects are given.
Raman and far-infrared spectra of polycrystalline samples of chloroform at 20 and 80 K are reported. Crystal field spilttings of the intramolecular fundamentals are observed as well as nine Raman and six infrared latt...
Raman and far-infrared spectra of polycrystalline samples of chloroform at 20 and 80 K are reported. Crystal field spilttings of the intramolecular fundamentals are observed as well as nine Raman and six infrared lattice modes. Spectra are interpreted in terms of a group theoretical analysis based on the molecular and crystal symmetries.
TiO2 was prepared by the oxidation of TiCl4 at relatively low deposition temperatures using spray pyrolysis. For a fixed carrier gas (N2) flow rate, the substrate temperature is the critical parameter determining the ...
TiO2 was prepared by the oxidation of TiCl4 at relatively low deposition temperatures using spray pyrolysis. For a fixed carrier gas (N2) flow rate, the substrate temperature is the critical parameter determining the film properties. Films made near 595 K contain only the anatase phase, adhere well to the glass substrate, and have a relative optical transmission of about 75% (between 450 and 850 nm), the value one calculates for the non-absorbing anatase phase in this region. These films have an absorption edge characteristic of a direct gap semiconductor with allowed transitions and optical gaps of 3.5-3.7 eV, depending on the porosity. At higher substrate temperatures (above 635 K), the resulting films have a cloudy appearance and they contain both the rutile and the anatase modifications, confirmed by X-ray diffraction. Lower temperature substrates reduce the deposition rate and yield more porous films. For the pure anatase films, the dark conductivities are about one order of magnitude larger, and the photoconductivity is about one order of magnitude smaller when measured with the sample in air, than those observed when the sample is in a vacuum. When the samples are in a vacuum, the conductivities of the clear films increase by about two orders of magnitude (from about 10(-10) to about 10(-8) S cm-1) when illuminated with light from an electrically programmable read-only memory eraser (mercury light), which gives an intensity of about 30-mu-w cm-2 at the sample. The photoresponse has two parts;the fast portion rises in less than 1 s to 99% of its final value, followed by a small slow rise portion. The slow response, which is more pronounced in the decay process, is interpreted as being due to the presence of surface trapping states.
We study the formulation of SU(2) Wess-Zumino-Witten theories with arbitrary level k away from criticality. Following the discussion of A.B. Zamolodchikov for minimal conformal models, we derive a counting argument th...
We study the formulation of SU(2) Wess-Zumino-Witten theories with arbitrary level k away from criticality. Following the discussion of A.B. Zamolodchikov for minimal conformal models, we derive a counting argument that leads to a prediction of the number of higher integrals of motion. We explicitly construct these higher integrals of motion for the special cases k = 1 and k = 2 (where these models are perturbed by some relevant primary field) and compare the results with the general counting argument. We consider renormalization group trajectories for k >> 1, and calculate the beta-function. Unlike the minimal models we do not find any link between fixed points in the SU(2) theories.
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