نتایج جستجو برای: gas laser
تعداد نتایج: 421702 فیلتر نتایج به سال:
The synthesis of metallic nanoparticles is an active area of academic and, more significantly, applied research in nanotechnology. Several methods have been introduced for the synthesis of these materials. The techniques for synthesizing aluminum nanoparticles can be divided into solidphase, liquid-phase and gas-phase processes. The solid-phase techniques include mechanical ball milling and mec...
The short-lived longitudinal plasma oscillations generated during filamentation in argon and nitrogen gas are measured with a specially designed current monitor. The magnitude and initial direction of the corresponding currents depend sensitively on laser polarization and nature of the gas. The results are interpreted as resulting from the competition between two forces acting on free electrons...
Optical trapping and manipulation of neutral particles has led to a variety of experiments from stretching DNA-molecules to trapping and cooling of neutral atoms. An exciting recent outgrowth of the technique is an experimental implementation of atom Bose-Einstein condensation. In this Letter, we propose and demonstrate laser-induced trapping for a new system--a gas of excitons in quantum well ...
We report on the lasing in air and pure nitrogen gas pumped by a single 800 nm femtosecond laser pulse. Depending on gas pressure, incident laser power and beam convergence, different lasing lines are observed in the forward direction with rapid change of their relative intensities. The lines are attributed to transitions between vibrational and rotational levels of the first negative band of t...
We consider a gas of attractively interacting cold fermionic atoms which are manipulated by laser light. The laser induces a transition from an internal state with large negative scattering length to one with almost no interactions. The process can be viewed as a tunneling of atomic population between the superconducting and the normal states of the gas. It can be used to detect the BCS ground ...
This paper gives an account of our progress towards performing femtosecond time-resolved photoelectron diffraction on gas-phase molecules in a pump-probe setup combining optical lasers and an X-ray free-electron laser. We present results of two experiments aimed at measuring photoelectron angular distributions of laser-aligned 1-ethynyl-4-fluorobenzene (C(8)H(5)F) and dissociating, laser-aligne...
We report on the use of a novel technique to measure the gas density from a pulsed gas jet. Deuterium gas is fully ionized with an intense picosecond laser, and the resulting electron density is measured by interferometric probing with a second picosecond pulse. We have applied this technique to characterize a cryogenically cooled, high-density gas jet.
The output spectrum of both gas and semiconductor lasers usually contains more than one frequency. Multimode operation in gas versus semiconductor lasers arises from different physics. In gas lasers, slow equilibration of the electron populations at different energies makes each frequency an independent single-mode laser. The slow electron diffusion in semiconductor lasers, combined with the sp...
High-harmonic generation (HHG) traditionally combines ~100 near-infrared laser photons to generate bright, phase-matched, extreme ultraviolet beams when the emission from many atoms adds constructively. Here, we show that by guiding a mid-infrared femtosecond laser in a high-pressure gas, ultrahigh harmonics can be generated, up to orders greater than 5000, that emerge as a bright supercontinuu...
The dynamics of laser-produced plasma (LPP) and its shockwave-induced density jump (SIDJ) were investigated in low-pressure ambient air during the laser pulse using an optical interferometer. A tiny SIDJ could be observed clearly in ambient air with pressure as low as 3 Torr even during the rising edge of a 7 ns laser pulse. It was shown that the density jump and ionization could seed laser-ind...
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