Time-dependent density functional theory (TD-DFT) is applied to model one-photon (OPA) and two-photon (TPA) absorption spectra in a series of conjugated cytotoxic dyes. Good agreement with available experimental data is found for calculated excitation energies and cross sections. Calculations show that both OPA and TPA spectra in the molecules studied are typically dominated by two strong peaks...

Bremsstrahlung spectra as a function of target thickness up to several radiation lengths to be used for particle production in high energy electron machines are investigated. The shower equations are cast in integral forms which are then solved by iteration. The iterations are performed up to the second generation photons; and the numerical results show that for most experiments the first gener...

In most models and theoretical calculations describing multiphoton ionization by infrared light, the dipole approximation is used. This is equivalent to setting the very small photon momentum to zero. Using numerical solutions of the (nondipole) three-dimensional time-dependent Schrödinger equation for one-electron (H-like) systems, we investigate the effect the photon-momentum transfer to the ...

We report the first observation of infrared (IR) and mass spectra of neutral, aliphatic amino acid clusters: the example presented herein is for (valine)(n), n = 2-5. The clusters are generated in a supersonic expansion and their IR spectra are recorded in various fragment and (valine)(n-1)H(+) (n = 2-5) mass channels. The ions are created by single photon ionization with a VUV laser at 118 nm ...

We demonstrate a bright, bandwidth-tunable, quasi-phase-matched single-waveguide source generating photon pairs near 900 nm and 1300 nm. Two-photon coincidence spectra are measured at a range of operating temperatures of a periodically-poled KTiOPO(4) (PPKTP) waveguide, which supports both type-0 and type-II spontaneous parametric down-conversion. We map out relative contributions of two-photon...

Emission spectra of avalanching n(+)p junctions manufactured in a standard CMOS technology with no process modifications were measured over a broad photon energy spectrum ranging from 0.8 eV to 2.8 eV at various temperatures. The temperature coefficients of the emission rates at different photon energies were determined. Below a photon energy of 1.35 eV the temperature coefficient of emission w...

The recent status of hard thermal photon production in relativistic heavy ion collisions is reviewed and the current rates are presented with emphasis on corrected bremsstrahlung processes in the quark-gluon plasma (QGP) and quark-hadron duality. Employing Bjorken hydrodynamics with an EOS supporting the phase transition from QGP to hot hadron gas (HHG), thermal photon spectra are computed. For...