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Now showing items 1-10 of 107

#### Photogeneration and recombination processes of neutral and charged excitations in films of a ladder-type poly(para-phenylene)

(American Physical Society, 1999-08-15)

We introduce a version of the cw photomodulation technique, measured far from the steady state, for obtaining the quantum efficiency, eta, of long-lived photoexcitations in pi-conjugated polymers. We apply this technique ...

#### Electron-energy-loss and optical-transmittance investigation of Bi2Sr2CaCu2O8

(American Physical Society, 1990-07)

The energy-loss function Im(-1/ε) of Bi2Sr2CaCu2O8 has been measured over the range Eloss=0.8 to 80 eV by transmission electron-energy-loss spectroscopy (EELS) (nonimaging). The energy and momentum resolution were 0.1 eV ...

#### Systematic scaling in the low-energy excitations of the t-J model in one and two dimensions

(American Physical Society, 1997-05-01)

We present an exact diagonalization study of the low-energy singlet and triplet states for both the one-dimensional (1D) and 2D t-J models. A scan of the parameter ratio J/t shows that for most low-energy states in both ...

#### Spin-charge separation in the two-dimensional Hubbard and t-J models at low electronic density

(American Physical Society, 1994-07)

The spin- and density-correlation functions of the two-dimensional Hubbard model at low electronic density [n] are calculated in the ground state by using the power method, and at finite temperatures by using the quantum ...

#### Dissipation in Wigner-Poisson systems

(AIP Publishing, 1994-04)

The Wigner-Poisson (WP) system (or quantum Vlasov-Poisson system) is modified to include dissipative terms in the Hamiltonian. By utilizing the equivalence of the WP system to the Schrodinger-Poisson system, global existence ...

#### Measurement of the spectral momentum distribution of valence-electrons in amorphous-carbon by (e, 2e) spectroscopy

(American Physical Society, 1994-01-15)

The spectral momentum density of the valence band of are evaporated amorphous carbon has been measured by (e, 2e) spectroscopy with significantly improved energy resolution relative to earlier studies. The valence band has ...

#### A new method of surface resistance measurement with a niobium triaxial cavity working at 2 K

(AIP Publishing, 1993-07)

A 1.5-GHz superconducting niobium triaxial cavity has been fabricated to study residual surface resistance of superconducting materials at 2 K. Unlike many other structures where the entire test samples have to be placed ...

#### Space-time digital holography: A three-dimensional microscopic imaging scheme with an arbitrary degree of spatial coherence

(AIP Publishing, 1999-10)

An on-line, spatiotemporal, digital holographic method is described and demonstrated experimentally. Using interferometric imaging, each scatterer of a three-dimensional object is encoded as a temporally modulated Fresnel ...

#### Effect of pressure on defect-related emission in heavily silicon-doped GaAs

(American Physical Society, 1994-11)

We report cryogenic high-pressure measurements of a defect-related emission at 1.25 eV in silicon-doped GaAs. The pressure measurements prove that the 1.25-eV photon energy is relative to the conduction band, implying a ...

#### Resonating-valence-bond wave function for the two-dimensional Heisenberg model on a triangular lattice

(American Physical Society, 1990-06)

A resonating-valence-bond (RVB) wave function for the triangular lattice is constructed by following the renormalized Hamiltonian approach (or Gutzwiller approximation) successfully developed for the square lattice. This ...