A STUDY OF THE PHOTOPHYSICAL AND PHOTOCHEMICAL PROPERTIES OF THE S8 MOLECULE The Quenching of Benzene,Naphthalene and Pyrene Fluorescence by S8 Molecules in S8 + Liquid Methanol System. I

Abstract

The energy of the first excited singlet state S₁ of S₈ is estimated as 89 ± 3 kcal · mole^?1. S₈ does not exhibit fluorescence, but quenches the fluorescence of certain sensitizers (benzene, naphthalene, pyrene) acting as an energy acceptor in the energy transfer process from the S₁ state of the sensitizer. The process of the quenching of donor fluorescence by S₈ was analysed using the Stern–Volmer equation.     

The effect of carrier level on tuning in amplitude-modulation masking

The effect of carrier level on tuning in modulation masking was investigated for noise and tonal carriers. Bandwidths of the modulation filters, estimated from the masked detection thresholds using an envelope power spectrum model, were independent of level for the noise carrier but seemed to decrease with increasing level for the tonal carrier. However, the apparently sharper tuning could be explained by increased modulation sensitivity and modulation dynamic range with increasing level rather than improved modulation-frequency selectivity. Consistent with this interpretation, the addition of a high-pass noise with a level adjusted to maintain the same threshold for the detection of the signal modulation for each carrier level used eliminated the effect of level on tuning. Overall, modulation filters estimated from psychophysical data do not depend on level in contrast to the modulation transfer functions obtained from neural recordings in the inferior colliculus in physiological studies. The results highlight differences between the characteristics of modulation processing obtained from neural data and perception. The discrepancies indicate the need for further investigation into physiological correlates of tuning in modulation processing.     

Die Wirkung ultravioletter und Röntgenstrahlung auf wäßrige Lösungen von Natriumperoxymolybdat

The effect of ultraviolet and X-ray radiation on the decay rate of aqueous solutions of sodium peroxymolybdate has been investigated. It was found that this system is very sensitive to radiation and decomposes to MoO ₄ ^2? obeying the rate equation of a zero order reaction. A mechanism for the reaction is proposed and discussed.     

Photosensitized degradation of polyethylene glycols in aqueous solutions. I. Viscosimetric measurements

Investigations were performed on acetone and benzene-sensitized degradation of triethylene glycol (TEG), polyethylene glycol 400 (PEG 400), and polyethylene glycol 4000 (PEG 4000) in aqueous solutions exposed to irradiation at λ = 254 nm and λ ～ 313 nm. The systems investigated were exposed at 20°C (±1°C) in both deaerated and undeaerated solutions. The course of the photosensitized degradation was examined viscosimetrically. The determined quantum yield (?) of chain scission decreases distinctly as the molecular weight of the polymer rises, irrespective of the wavelength of the light absorbed and deaeration of system exposed.     

Nonlinear parabolic equations, relaxation and roughness

In a recent paper, Aubin and Coulouvrat (1998) dealt with equations of motion in the fluid in relaxation - mathematically: Burgers' equations, physically: continuity equations, Navier-Stokes equations, energy bilance, and equations of relaxation. A related equation of Ginzburg and Landau type (1965) extended for the kinetic depinning transitions takes its form

(0)     

Nonlinear parabolic equations, relaxation and roughness

In a recent paper, Aubin and Coulouvrat (1998) dealt with equations of motion in the fluid in relaxation - mathematically: Burgers' equations, physically: continuity equations, Navier-Stokes equations, energy bilance, and equations of relaxation. A related equation of Ginzburg-Landau type (1965) extended for the kinetic depinning transitions takes its form

(0)     

Short-range order in Valenta model of thin films

The present paper deals with the Valenta model for magnetic thin films extended to the entropy construction in its pair representation. The problem of the thin films theory is old, but the Valenta model introduced fifty years ago seems to be still an effective approach requiring however, some modifications. The most important one is connected with the improvement of the entropy construction in the self-consistent way when the correlations are taken into account. The idea is introduced in the present paper and discussed in detail.     

Synthesis and Characterization of Polyether Adducts of Barium and Strontium Carboxylates and Their Use in the Formation of MTiO(3) Films

The synthesis, characterization, and reactivity of new polyether adducts of strontium and barium carboxylates of general composition M(O(2)CCF(3))(n)()(L) (M = Ba, L = 15-crown-5, (1); M = Ba (2), Sr (3), respectively, with L = tetraglyme are reported. The compounds were synthesized by reaction of BaCO(3) or MH(2) (M = Sr or Ba) with organic acids in the presence of the polyether ligands. These compounds have been characterized by IR and (13)C and (1)H NMR spectroscopies, elemental analyses, and thermogravimetric analysis. The species Ba(2)(O(2)CCF(3))(4)(15-crown-5)(2) (1) and [Ba(2)(O(2)CCF(3))(4)(tetraglyme)](infinity) (2), were also characterized by single-crystal X-ray diffraction. Ba(2)(O(2)CCF(3))(4)(15-crown-5)(2) (1) crystallizes in the orthorhombic space group Cccm with cell dimensions of a = 13.949(1) ?, b = 19.376(2) ?, c = 16.029(1) ?, and Z = 8. [Ba(2)(O(2)CCF(3))(4)(tetraglyme)](infinity) (2) crystallizes in the monoclinic space group C2/c with cell dimensions of a = 12.8673(12) ?, b = 16.6981(13) ?, c = 15.1191(12) ?, beta = 99.049(8) degrees, and Z = 4. Compounds 1-3 thermally decompose at high temperatures in the solid state to give MF(2). However, solutions of compounds 1-3 dissolved in ethanol with Ti(O-i-Pr)(4) give crystalline perovskite phase MTiO(3) films, or in the case of mixtures of 2 and 3, Ba(1)(-)(x)()Sr(x)()TiO(3) films below 600 degrees C when spin coated onto silicon substrates and thermally treated. The crystallinity, purity, and elemental composition of the films was determined by glancing angle X-ray diffraction and Auger electron spectroscopy.