It was found that a local charge-transfer excitation on the donor(D)-acceptor(A) pair leads to semimacroscopic valence change from quasi-ionic (${\mathit{D}}^{+}$${\mathit{A}}^{\mathrm{\ensuremath{-}}}$) quasineutral (${\mathit{D}}^{0}$${\mathit{A}}^{0}$) states in organic molecular-compound TTF-chloranil with mixed DA stacks. Photogenerated neutral-ionic domain walls, which are responsible for anomalous photoconductivity, show temporal annihilation due one-dimensional recombination.

It was observed that bi-directional phase changes can be triggered by genuine photoexcitation between two phases with different bond structures in polydiacetylenes. The photoinduced transition found to mediated photogeneration of charge carriers (and not excitons). extremely high efficiency is perhaps due cooperative interaction the locally photoconverted domains.

The temperature and pressure dependences of the dielectric constants have been measured on mixed-stack organic charge-transfer crystal, tetrathiafulvalene-p-chloranil, in a frequency range from 100 Hz to 10 MHz. response increases remarkably with decreasing down ${\mathit{T}}_{\mathit{c}}$=81 K, where neutral-to-ionic (NI) phase transition occurs. On other hand, applied at room temperature, change is less remarkable, whereas dc conductivity ${\mathrm{\ensuremath{\sigma}}}_{\mathrm{dc}}$...

Third-order harmonic generation has been measured on highly oriented polydiacetylene (PDA) films prepared by the vacuum deposition method. Experimental values of third-order electric susceptibility χ(3) for pumping laser polarized parallel to polymer chain show a sharp three-photon resonance 1Bu exciton in PDA. Potential usefulness these PDA evaporated nonlinear optical applications is suggested.

Intrinsic paramagnetic defects have been detected by ESR measurements in tetrathiafulvalene -$p$- chloranil single crystals, associated with the neutral-to-ionic phase transition at ${T}_{c}=84$ K. Two kinds of species are identified delocalized spins propagating on either donor or acceptor sites. Total spin density and electric conductivity were found to increase discontinuously as temperature is lowered across ${T}_{c}$. These features attributed formation mobile solitonlike (and...

The modulus and phase of the complex third-order nonlinear optical (NLO) susceptibility \ensuremath{\chi}${\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}^{(3)}$(-3\ensuremath{\omega};\ensuremath{\omega},\ensuremath{\omega},\ensuremath{\omega}) have been measured on an all-trans silicon polymer, poly(dihexylsilane), over a wide photon energy range. Several distinct structures observed in \~{}\fi{}}}^{(3)}$ spectra are excellent agreement with theoretical results one-dimensional (1D) exciton...

A stable and reproducible negative-resistance effect has been observed in various mixed-stack organic charge-transfer crystals having ionicities close to the neutral-ionic phase boundary. Systematic studies on several kinds of single indicate that this is an intrinsic property, arising from dynamics charge-carrying defects with fluctuating molecular valence one-dimensional (1D) stacks. microscopic mechanism negative resistance proposed taking account three-dimensional electrostatic...

Experimental evidence is presented that indicates the occurrence of a temperature-induced neutral-ionic transition occurring at ${\mathit{T}}_{\mathit{c}}$\ensuremath{\simeq}205 K in mixed-stack organic charge-transfer crystal, 3,3',5,5'-tetramethylbenzidine-7,7,8,8-tetracyanoquinodimethane (TMB-TCNQ). The characterized by large first-order-like jump magnetic susceptibility and dimeric distortion stacks similar to those observed tetrathiafulvalene-chloranil (TTF-CA). However, contrary case...

The electric conductivity has been measured on the mixed-stack charge-transfer crystal tetrathiafulvalene (TTF) -p-chloranil (CA) as a function of temperature (T>30 K) and pressure (P<11 kbar). On basis experimental results, P-T phase diagram is presented for state in TTF-CA.

The transmission and phase-shift spectra for millimeter electromagnetic waves are obtained a two-dimensional (2D) square lattice array made of ${\mathrm{Si}}_{3}{\mathrm{N}}_{4}$ spheres diameter $\ensuremath{\simeq}3.2$ mm. results compared with the theoretical 2D photonic-band structures that take account lifetime effect due to radiative energy decay. It is found incidence-angle dependence observed in excellent agreement calculated in-plane dispersion curves photonic bands frequency phase...

A binary system of parallel hard spherocylinders and spheres are considered to examine influence addition spherical molecules the pure rod-like molecules, especially on structure smectic-A phase. Free energy is calculated through second virial approximation, nematic–smectic-A transition estimated by stability analysis nematic state with sinusoidal density fluctuation. Constant pressure Monte Carlo simulation also used confirm a prediction which indicates that induces phase as microphase...

Third-harmonic generation measurements have been made for the first time on oriented films of halogen-bridged mixed-valence platinum complexes pump wavelength region from 0.6 to 1.0 μm. The ‖χ(3)(−3ω;ω,ω,ω)‖ spectra obtained by Maker’s fringe method show a distinct peak at about 1.8 eV with value 4×10−11 esu. From comparison electroabsorption data, this has identified two-photon resonance forbidden exciton in Pt-halogen chains. One-dimensional states compound take an important role...

A reproducible current switching effect has been observed in various mixed-stack organic charge transfer crystals whose ionicities are close to the neutral-ionic phase boundary. This appears be related intrinsic nonlinear conductivity, which recently reported these crystals. a reasonably large delay time and our results indicate that it is bulk property of Discussion given on possible mechanism this effect.

Polarized reflectivity spectra have been measured on K- and Rb-tetracyanoquinodimethane single crystals over a wide temperature range covering respective structural phase-transition temperatures. From an analysis of the intramolecular vibration charge-transfer exciton bands, thermal variations dimeric molecular displacements at phase transition are investigated. The temperature-dependent intensity width dimerization-induced ${a}_{g}$ bands can provide microscopic information, which is...

The effects of uniaxial stress on the exciton reflection spectra zinc-blende CuCl have been investigated experimentally and theoretically. From a comparison experimental results with theory which takes account strain, spin-exchange, stress-induced $k$-linear terms, it is established that term playing an essential role in anomalous transverse-longitudinal mode mixing ${Z}_{3}$ observed configuration $\stackrel{\ensuremath{\rightarrow}}{\mathrm{P}}\ensuremath{\parallel}[001]$...

We analyzed the relationship between nanometer-scale structure of amylopectin and physicochemical properties such as thermal starch granules higher-order internal evaluated by using synchrotron radiation X-ray scattering scanning electron microscopy. In this study, a line allelic mutants rice lacking in branching enzyme IIb (BEIIb) activity their endosperm were used sources. The crystal lattice changed from A-type to C- B-type. nanoscale cluster size, structures varied among mutant lines....

Electrical and magnetic properties have been investigated for (BEDT-TTF)(TCNQ) which is composed of BEDT-TTF sheets TCNQ columns. The metal-insulator transition temperature ${\mathit{T}}_{\mathrm{MI}}$, 330 K at ambient pressure, decreases down to 40 by applying hydrostatic may be ascribed the change in both intermolecular transfer energy band filling (molecular valence). Measurements EPR susceptibility indicate that low-temperature states columns are insulators, perhaps due strong electron...

Optical reflectivity spectra were measured for the superconducting fulleride ${\mathrm{K}}_{3}$${\mathrm{C}}_{60}$ and pristine ${\mathrm{C}}_{60}$ single crystals in wavelength region from infrared to ultraviolet. High-quality samples of with flat surfaces grown this purpose by cosublimation both potassium metal. A sharp plasma edge was found at 0.73 eV reflection ${\mathrm{K}}_{3}$${\mathrm{C}}_{60}$. quantitative discussion is given on conduction band structures based parameters derived a...