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Phosphate is an essential element for plant nutrition, and therefore it is important to know the dynamics of sources of phosphorus (P) with different solubility in soils that naturally have low levels of available P and that fixate or adsorb the aggregated P. For that purpose four doses of P were applied (0, 300, 600 y 1200 mg.kg -1 ) to an Andisol soil type from the IX Region (Chile), employing fertilizers that differ in their solubility, triple superphosphate (TSP) and Rock phosphate (RF), and afterwards they were maintained in controlled temperature and humidity conditions. Available P – (Olsen) was measured 1, 7, 14, 28 and 120 days after applications. The treatments that received TSP, showed a rapid increase in available P, followed by an initial rapid decrease on the first day and later by a slow steady decrease. When RF was applied the level of available P increase slowly in time, but never reaches the levels attained with TSP. The P adsorption after one day of applying TSP, was explained by a lineal regression, Available P=0.07xP applied + 0.64 (R 2 =0.99; P

We describe the synthesis of a series of new unsymmetrically substituted tetraselena- and dithiadiselenafulvalenes bearing one or two functionalities such as diethylacetal, formyl or hydroxymethyl groups. The physical properties and spectroscopic data of these new π-donors are reported.

We report the synthesis of a new series of dithiadiselenafulvalenes. We describe the electrical conductivity and the FTIR spectra of both their radical cation salts and their charge transfer complexes with TCNQ.

Resume Une etude de relations structure—activite a ete effectuee sur une serie de quinolones et naphtyridines antibacteriennes. Les vecteurs d'autocorrelation ont ete utilises comme descripteurs structuraux. Les variables obtenues ont ete traitees par une analyse en composantes principales, une analyse discriminante et une classification ascendante hierarchique. Sur un echantillon de 122 composes les molecules actives et inactives sont correctement discriminees par deux variables.

This paper is a review of the electrical properties of organic materials containing unsymmetrically substituted TTF and TSF. Two series of these donors were prepared using a Wittig-type reaction with the sulfur compounds, and a cross-coupling method with their selenium analogues. Their radical-cation salts were synthesized by electrochemical oxidation and their charge-transfer complexes were obtained chemically using TCNQ and its 2,5-dimethylated derivative DMTCNQ. The crystal structures were determined by X-ray diffraction when single crystals were obtained. The electrical properties are correlated to the structural data.

In this report we will present the characteristic aspects of nuclear spin relaxation in ID organic conductors. The diffusive picture of the electron motion in conduction chain (in other words the diffusive character of the response function for small q SOW excitation, q λ ≪ 1, λ being the mean-free-path)and the inter-chain coupling (or the electron hopping between the conduction chains) will be discussed.

We report a systematic investigation under pressure of spin susceptibility, nuclear relaxation rate and temperature dependence of the resistivity in the charge transfer salts TTF-TCNQ, TMTTF-TCNQ and HMTSF-TCNQ. The very large pressure dependences observed in the TTF-TCNQ family, which cannot be explained solely by the band broadening point to the picture of a magnetism governed by the properties of a one dimensional strongly correlated electron gas. An interpretation of our data in terms of the Hubbard model for one dimensional itinerant magnetism provides an estimation of the ratio electron-electron repulsion to band width U/4t ≈ 1 in TTF-TCNQ at ambient pressure. The effects of correlations tend to become weaker for the selenium compounds, in particular for HMTSF-TCNQ, or as pressure is applied to the TTF-TCNQ family.

The new charge transfer complex t-TTF-TCNQ, whose unsymmetric cation is intermediate between TTF and HMTTF, presents a regular stacking of both donor and acceptor chains. We show that this compound has a metallic behavior at high temperatures and undergoes one metal-insulator transition near 81 K. Its electrical and magnetic properties are examined in connection to this phase transition and the effective dimensionality.

X-ray diffuse scattering experiments on the superconducting salts (TMTSF)2X with X = PF6, AsF6 and ClO4 reveal no charge density wave instability, in contrast with the poorly conducting (TMTTF)2PF6 salt. New structural phase transitions coinciding with conductivity anomalies are found in (TMTSF)2NO3, (TMTSF)2ReO4, and (TMTTF)2ClO4. It is suggested that they correspond to order-disorder transitions involving the non-centrosymmetric counter ions. Relationships between these structural instabilities and superconductivity are also discussed.

We report the synthesis and characteristics of two new unsymmetrical π donors in the TSF family, dimethyl-4,5 and trimethylene-4,5 tetraselenafulvalenes (UDMTSF and TTSF). The temperature dependences of the electrical conductivity are also reported for the charge transfer complex TTFS-TCNQ and for the radical cation salt (UDMTSF) 2 ClO 4 .

s Service): alors que bis(trim6thyl6ne)-3,4;3',4' tr Spencer, Cava & Garito, 1976) et l'influence de la perte de symr la temperature de transition est 81 K. Un signal RPE de grande largeur laisse pr6voir des interactions tridimensionnelles fortes, plus fortes que celles pr6sentes dans les cristaux de T T F T C N Q et H M T T F T C N Q (hexam&hyl+net6trathiafulval6ne-t&racyanoquinodim6thane). 2812 TRIMETHYLENETETRATHIAFULVALENE-TETRACYANOQUINODIMETHANE Partie exp6rimentale

The 13C NMR relaxation time T1 and Knight shift K have been measured in the organic conductor TTF-TCNQ with 13C-enriched TTF molecules. A clear anomaly in T1 and K shows that the gap in the conducting band of the TTF stack opens only below 38K. No T1 or K anomalies have been observed either at 54 or at 49K. The authors propose a new decomposition of the total spin susceptibility into contributions coming from individual TTF and TCNQ bands, which is based on 13C NMR Knight shift data. The salient new information provided by this work is that the ratio chi Q/ chi F is larger than unity above 60K. The present results have been used to reanalyse the 1H NMR data in the literature. They have reached the conclusion that the TTF band is broader ( approximately 0.65 eV) than the TCNQ band ( approximately 0.40 eV). The observed large enhancement of the Korringa relation suggests that the Coulomb correlation energy U is of the order of the band width for both stacks.

Les poly(parachlorométhylstyrène) et poly(parabromostyrène) présentent des propriétés lithographiques intéressantes sous irradiation électronique. Une sensibilité élevée, associée à de bonnes propriétés de résistance à la gravure plasma ainsi qu'à une bonne résolution en font des matériaux de choix dans le cadre de la microlithographie à haute performance.

Polyacetylene films strongly react with air, when conserved at room temperature and atmospheric pressure. We present here an experimental electron spin resonance (ESR) study on the variation of the linewidth and number of spins with time and temperature of cis- and trans-(CH)x films of different thicknesses. It is shown that this evolution is qualitatively and quantitatively different for the two isomers. The number of resonant spins increases with time with a characteristic time of the order of 8 hours in the case of the cis isomer. For the trans isomer, the number of resonant spins, which is an order of magnitude greater than the final value of the cis isomer, is remarkably constant with time while the linewidth and amplitude are not. In the light of these results, the origin and nature of the observed resonant spins are discussed.

This communication describes the synthesis and the electrochemical properties of a new type of donor containing sulfur or selenium atoms: the dimethyltetramethylenetetraselenafulvalene 1 and the dimethyltetramethylenetetrathiafulvalene 2 . The electrical conductivity of their charge transfer complexes and of some of their radical cation salts are reported.

Conductivity measurements on isotopically substituted single crystals of TTF-TCNQ show a relatively large shift in the phase transition temperatures at 52.5 K (T1) and 37.7 K (T3). Deuteration of both TTF and TCNQ chains increases T1 by 0.75 ± 0.15 K, N15 substitution increases T1 by 0.6±0.1 K while deuteration of the TTF chains apparently has no significant effect. Different possible interpretations of these results are briefly discussed.

A new chemical preparation of hexamethylenetetrathiofulvalenium and of the HMTTF-TCNQ charge transfer complex is described. The d.c. conductivity has been measured as a function of temperature; it shows a broad maximum (Tmax ≃ 75 K) followed by two transitions (T c1 = 49 ± 1 K, Tc2 = 43 ± 1 K). The static paramagnetism, E.P.R. and specific heat have been measured; they indicate that T c2 must be associated with the appearance of a periodic lattice distortion of the HMTTF chains which (dominate observed behaviour). The line-width is determined by interactions between chains which are more efficient in this compound than in TTF-TCNQ, in agreement with the behaviour of the electrical conductivity.

Cette mise au point porte sur la serie des complexes a transfert de charge du tetrathiofulvalene-tetracyanoquinodimethane (TTF-TCNQ). L’ensemble des travaux que nous avons faits est presente et situe dans le courant general de ce theme de recherches La fabrication de ces nouveaux materiaux, les donnees physico-chimiques, les proprietes structurales et physiques sont analysees. Des correlations entre les differents materiaux et un effort de classification, ont ete effectues pour comprendre leur comportement et essayer de prevoir de nouveaux composes.

Measurements at room temperature of the electronic spin lattice relaxation time in tetrathiafulvalene tetracyanoquinodimethan (TTF-TCNQ) and rubidium-TCNQ (II) are reported. A tentative discussion of the experimental results is given.

Poly-4-bromostyrene (PBS) is shown to have desirable combination of properties, including high sensitivity and high resolution. As a consequence, it is a very attractive candidate for high performance electron beam lithography. The dependence of resist contrast and sensitivity on molecular weight is reported.

Polymers bearing tetrathiafulvalene groups have been tested under e-beam and UV irradiation. The dependence of resist sensitivity on molecular weight is reported. Resolution between 0,1 and 0, 4 μm were obtained. These polymers are shown to have desirable combination of properties, including high sensitivity and high resolution.

Studies on polyacetylene doped with MoCl5, SbF5, have shown, first that during desorption under vacuum the weight decrease of the samples was low, second that these compounds induce a stabilization of the polyacetylene in what concern the conductivity. We have extended these studies to rare earth salts to see their eventual stabilization effect on polyacetylene.

We present in this communication, new data obtained on the charge-transfer complex TMTTF-TCNQ. After the discovery of the conducting properties of the quasi one-dimensional charge-transfer complex TTF-TCNQ,1-4 it was appealing to study the electronic properties of the salt in which the protons of the donor molecule are substituted by four methyl groups which may bring about some disorder in the electronic states.

Temperature dependence of the dynamic nuclear polarization enhancement AL of the protons in tetrathiafulvalinium-tetracyanoquinodimethan salt (TTF-TCNQ) and potassium-TCNQ salt is reported. In TTF-TCNQ, AL is temperature-independent in the range 150 to 300 K; in K-TCNQ, AL is strongly temperature-dependent. These results, and the knowledge of the frequency dependence of the relaxation time T1 of the protons allow to determine the cut-off frequency vC of the ld diffusion mechanism with respect to the nuclear and electronic frequencies vI and vS. vC is larger than 10 GHz in TTF-TCNQ and vC is of the order of vI in K-TCNQ. Moreover, because of the large enhancement AL observed in K-TCNQ, the T1 anisotropy is determined on single crystals. Nous presentons, en fonction de la temperature, la variation de l'accroissement AL du signal des protons par polarisation nucleaire dynamique dans les deux sels de tetracyanoquinodimethane (TCNQ): tetrathiafulvalene (TTF)-TCNQ et potassium-TCNQ. Pour TTF-TCNQ, AL est independant de la temperature dans le domaine 150 a 300 K, alors que pour K-TCNQ, AL varie fortement. Ces resultats et la connaissance de la dependance en frequence du temps de relaxation T1 des protons, permettent de situer la frequence de coupure vC du mecanisme de diffusion ld par rapport aux frequences de travail nucleaire vI et electronique vS. vC est superieur a 10 GHz dans TTF-TCNQ et de l'ordre de vI dans K-TCNQ. Par ailleurs, grǎce au fort accroissement du signal des protons observe dans K-TCNQ, nous avons mis en evidence, sur monocristaux, l'anisotropie de T1.

In the present work some preliminary studies on the kinetics and the optimum conditions for the preparation of polyacetylene films are reported using the soluble Ti(OC4H9)4Al(C2H5)3 system, as well as the observation of the morphology of the films by electron microscopy. The kinetic curves obtained show two distinct parts: a rapid consumption of acetylene, followed by a retarding of the rate due to the polyacetylene film formed. If the rate of polymerization is plotted as a function of ageing time of the catalyst for a ratio Al Ti = 4 , a maximum is found for about one hour.

The polymorphism of the di- (4 - alkoxyphenyl) and di- (4 - alkanoyloxyphenyl) tetrathiafulvalenes (TTF) is investigated. In the dialkoxy series, the short chain derivative exhibits a smectic G phase and a nematic phase. The latter phase disappears in the long chain derivative. The dialkanoyloxy derivatives exhibit a smectic G phase (for short chains) and a smectic C phase (for long chains). A plot of the mesormorphic-isotropic transition temperatures against the number of carbon atoms of the substituent shows the usual odd-even effect. Some tetra (alkoxyphenyl) tetrathiafulvalenes are described, unfortunately they have no mesomorphic properties.

A new chemical preparation of hexamethylenetetrathiofulvalenium and of the HMTTF-TCNQ charge transfer complex is described. The d.c. conductivity has been measured as a function of temperature; it shows a broad maximum (Tmax ≃ 75 K) followed by two transitions (T c1 = 49 ± 1 K, Tc2 = 43 ± 1 K). The static paramagnetism, E.P.R. and specific heat have been measured; they indicate that T c2 must be associated with the appearance of a periodic lattice distortion of the HMTTF chains which (dominate observed behaviour). The line-width is determined by interactions between chains which are more efficient in this compound than in TTF-TCNQ, in agreement with the behaviour of the electrical conductivity.

C 10 H 8 ClNO 3 S cristallise dans P1 avec a=18,110, b=9,076 et c=7,271 A, α=111,29, β=100,10 et γ=94,75 o , Z=4; affinement jusqu'a R=0,049. Le compose etudie, un puissant antibacterien, appartient a la famille des quinolones. Les longueurs de liaison different quelque peu de celles de l'acide oxolinique. Les deux molecules independantes sont tres proches en ce qui concerne les longueurs et angles de liaison. Elles donnent des dimeres tete-beche avec un recouvrement important de leurs nuages π. Les autres interactions intermoleculaires sont de type van der Waals

We have synthetized and purified the dimethyltrime-thylene tetraselenafulvalene (DMtTSeF). From this unsymmetrical molecule a series of radical cation salts has been prepared by electro-oxidation. This new series, isostoicheiometric and isomorphous with the TMTSeF salts, exhibits a metallic behavior down to 0,1 K without any sign of either a metal-insulator or a superconducting phase transition.

The structure and physical properties of tetramethyl-tetrathiofulvalene (TMTTF) salts are reviewed. New results are given about (TMTTF)2 PF6, (TMTTF)2 ClO4 and the selenium analog (TMTSF)2 ClO4. An experimental relationship is shown between the electrical and magnetic properties and the closest contacts S-S or Se-Se of neighbouring stacks.

Measurements are reported of the b axis conductivity of HMTTF-TCNQ under hydrostatic pressures up to 33 kbar, and the room temperature, ambient pressure conductivity anisotropies. The two transitions seen in the conductivity at 49K and 43K at ambient pressure fall in temperature when pressure is applied; the lower transition is absent above 3 kbar and the upper transition falls linearly at 1.5K kbar-1. The low-temperature insulating behaviour at ambient pressure is rapidly replaced by weakly metallic behaviour, which at 10 kbar is very similar to that seen in HMTSF-TCNQ at ambient pressure. At higher pressures the resistivity was still falling at 1.2K. It is suggested that HMTTF-TCNQ above 3 kbar and HMTSF-TCNQ at ambient pressure undergo distortions on predominantly one type of stack. A unified picture of the pressure behaviour of this series of TCNQ salts is presented; the Peierls distortions in TTF-TCNQ and TSF-TCNQ occur when the transverse conduction is diffusive and the system is in the one-dimensional regime, whereas HMTTF-TCNQ and HMTSF-TCNQ distort when transverse motion is coherent and an anisotropic three-dimensional band structure picture is appropriate.

[(TMTSeF)1-x(TMTTF)x]2ClO4 alloys have been studied under pressure for pressures up to 18 kbar through resistivity measurements. On substitution of TMTSeF in the superconducting compound (TMTSeF)2ClO4 with TMTTF a low temperature metal-insulator (M-I) transition is found at ambient pressure; above some critical pressure, P c, the M-I transition is suppressed giving rise to a metallic state to the lowest temperatures considered in this study. The phase diagrams of the various alloys are of the same form although Pc increases with increasing TMTTF concentration. Superconductivity was not observed in any of these materials in the metallic high pressure regime.

Article de synthese: revue breve des procedes utilises dans la production de circuits integres, caracteristiques d'un bon photoresist (contraste, sensibilite, adherence, resolution, resistance a la gravure), revue des composes entrant constituant des resists negatifs (diazide/polydiene, polycinnamate de vinyle) et positifs (novolaque/diazonaphtalenone)

Pressure coefficients of the spin susceptibility, nuclear relaxation rates and resistivity have been measured in TTF-TCNQ, TMTTF-TCNQ and HMTSF-TCNQ. We point out that the very large pressure coefficients are not in agreement with the significantly smaller coefficients measured in optical absorption experiments under pressure. We propose an explanation of the magnetic properties of TTF-TCNQ and related compounds in terms of itinerant one dimensional antiferromagnetism. Using the Shiba-Pincus Hubbard model calculation we derive a value U/4t∥ close to unity which points towards the importance of correlations in the TTF-TCNQ family.

The linear axial compressibilities of a deuterated sample of TTF-TCNQ (tetrathiafulvalene-tetracyanoquinodimethane) have been measured by a neutron diffraction technique under hydrostatic pressures up to ∼ 20 kbar at room temperature. The observed compressibilities along the crystallographic axes are, respectively, ka = 2.7, kb = 4.7 and kc = 3.2 x 10-12 cm2/dyne. These results indicate a strong Coulomb type interchain interaction. It is suggested that the dominant part of the crystal cohesion results from a stacking of strongly dynamically polarized TTF and TCNQ molecules acting as effective molecular dipoles.