相关论文: Excited electron-bubble states in superfluid heliu…

We investigate the effect of dynamic electron correlation on high-harmonic generation in helium atoms using intense visible light (\lambda=390nm). Two complementary approaches are used which account for correlation in an approximate manner:…

While the variational principle for excited-state energies leads to a route to obtaining excited-state densities from time-dependent density functional theory, relatively little attention has been paid to the quality of the resulting…

We examine Maris' recent suggestion that the fission of electron-inhabited bubbles in liquid helium may give rise to a new form of electron fractionization. We introduce a one-dimensional toy-model--a simplified analogue of the helium…

The properties of helium-filled nanopores in amorphous silicon are elucidated by combining theoretical knowledge of helium electronic structure with the results of Scanning Transmission electron microscopy/electron energy loss spectroscopy…

The sum rule formalism is used to evaluate rigorous bounds for the density and current static response functions in superfluid helium at zero temperature. Both lower and upper bounds are considered. The bounds are expressed in terms of…

We study superfluidity in the 1D Bose-Hubbard model using a variational matrix product state technique. We determine the superfluid density as a function of the Hubbard parameters by calculating the energy cost of phase twists in the…

Spatially resolved electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) has been used to investigate as fluidic phase in nanoubbles embedded in a metallic Pd90Pt10 matrix. Using the 1s->2p…

Time-dependent response theories are foundational to the development of algorithms that determine quantum properties of electronic excited states of molecules and periodic systems. They are employed in wave-function, density-functional, and…

A novel 3-electrode cell type is introduced to run parametrical studies of H$_2$ evolution in an alkaline electrolyte on porous electrodes. Electrochemical methods combined with a high-speed optical measurement system are applied…

We have used a Hartree-type electron-helium potential together with a density functional description of liquid $^4$He and $^3$He to study the explosion of electron bubbles submitted to a negative pressure. The critical pressure at which…

Electrons in image-potential states on the surface of bulk helium represent a unique model system of a two-dimensional electron gas. Here, we investigate their properties in the extreme case of reduced film thickness: a monolayer of helium…

We study nonlinear inter-subband microwave absorption of electrons bound to the liquid helium surface. Already for a comparatively low radiation intensity, resonant absorption due to transitions between the two lowest subbands is…

When an electron (or positronium atom) is injected into liquid helium with nearly zero energy, a bubble quickly forms around it. This phenomenon (which also occurs in liquid hydrogen, liquid neon and possibly in solid helium) lowers the…

We combine experimental and theoretical approaches to explore excited rotational states of molecules embedded in helium nanodroplets using CS$_2$ and I$_2$ as examples. Laser-induced nonadiabatic molecular alignment is employed to measure…

Torsional oscillator experiments on solid 4He show frequency changes which suggest mass decoupling, but the onset is broad and is accompanied by a dissipation peak. We have measured the elastic shear modulus over a broad frequency range,…

We present a first principles strategy for developing state-specific density functional approximations for excited states. We first clarify why approaches based on conventional ground state approximations miss density-driven correlations,…

We study two techniques to create electrons in a liquid helium environment. One is thermionic emission of tungsten filaments in a low temperature cell in the vapor phase with a superfluid helium film covering all surfaces; the other is…

We present a linear-response formalism for a system of correlated electrons out of equilibrium, as relevant for the probe optical absorption in pump-probe experiments. We consider the time dependent optical conductivity $\sigma(\omega,t)$…

The investigation of the mobility \(\mu\) of quasi-free electrons in dense, cold helium gas as a function of its density \(N\) is made difficult by the fact that a significant fraction of electrons is localized in low mobility bubbles. The…

Molecular absorption and photo-electron spectra can be efficiently predicted with real-time time-dependent density-functional theory (TDDFT). We show here how these techniques can be easily extended to study time-resolved pump-probe…