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Femtosecond

About: Femtosecond is a research topic. Over the lifetime, 35106 publications have been published within this topic receiving 691405 citations. The topic is also known as: 1 E-15 s & fs.


Papers
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Journal ArticleDOI
13 Jan 2006-Science
TL;DR: A combination of time-resolved photoelectron spectroscopy, multidimensional coincidence imaging spectroscopic, and ab initio computation is used to trace a complete reactant-to-product pathway—the photodissociation of the nitric oxide dimer—from the molecule's point of view, on the femtosecond time scale.
Abstract: The coupled electronic and vibrational motions governing chemical processes are best viewed from the molecule's point of view-the molecular frame. Measurements made in the laboratory frame often conceal information because of the random orientations the molecule can take. We used a combination of time-resolved photoelectron spectroscopy, multidimensional coincidence imaging spectroscopy, and ab initio computation to trace a complete reactant-to-product pathway-the photodissociation of the nitric oxide dimer-from the molecule's point of view, on the femtosecond time scale. This method revealed an elusive photochemical process involving intermediate electronic configurations.

161 citations

Journal ArticleDOI
TL;DR: The first table-top hard X-ray plasma source driven by a mid-infrared source provided 10^9 photons per pulse as mentioned in this paper, which was the first table top hard X ray source with the capability of delivering 10
Abstract: The first table-top hard X-ray plasma source driven by a mid-infrared source provides 10^9 photons per pulse.

161 citations

Journal ArticleDOI
TL;DR: In this article, a femtosecond chirped-pulse oscillator was demonstrated to achieve sub-40 GHz energy at average power levels of 1 and 2.5 GHz.
Abstract: Broadening the ultrashort laser pulse in a Kerr-lens mode-locked laser by net positive round-trip group-delay dispersion has proven to be a powerful concept for scaling the pulse energy directly achievable with a femtosecond laser oscillator without external amplification. Drawing on this concept, we demonstrate here Ti : Sa chirped-pulse oscillators delivering sub-40 fs pulses of 0.5 μJ and 50 nJ energy at average power levels of 1 and 2.5 W (repetition rate: 2 and 50 MHz), respectively, which to the best of our knowledge constitute the highest pulse energy and average power achieved with a femtosecond ( 1015 W cm−2 (when focused down to ~1 μm2), both of which represent record values from a laser oscillator. These pulse parameters appear to be limited merely by the pump power available, affording promise of scaling chirped-pulse femtosecond Ti : Sa oscillators to microjoule pulse energies and—by simultaneous spectral broadening—towards peak power levels of several hundred megawatts.

161 citations

Journal ArticleDOI
TL;DR: Tunable femtosecond pump-near IR probe measurements on InAs/CdSe/ZnSe core/shell1/shell2 nanocrystal quantum dots were conducted to quantify spontaneous carrier multiplication, showing no signs of carrier multiplication within that range.
Abstract: Tunable femtosecond pump-near IR probe measurements on InAs/CdSe/ZnSe core/shell1/shell2 nanocrystal quantum dots were conducted to quantify spontaneous carrier multiplication previously reported in this system. Experimental conditions were chosen to eliminate the need for determining absolute wavelength dependent cross sections of the nanocrystals and allow direct comparison of band edge absorption bleach kinetics for different excitation energies up to 3.7 times the band gap. Results for two sample sizes show no signs of carrier multiplication within that range. This result is discussed in light of reports describing occurrence of this novel phenomenon in quantum dots based on this as well as numerous other semiconductor materials.

161 citations

Journal ArticleDOI
TL;DR: A novel approach for efficient tuning of optical properties of a high refractive index subwavelength nanoparticle with a magnetic Mie-type resonance by means of femtosecond laser irradiation based on ultrafast photoinjection of dense electron-hole plasma within such nanoparticle, drastically changing its transient dielectric permittivity.
Abstract: We propose a novel approach for efficient tuning of optical properties of a high refractive index subwavelength nanoparticle with a magnetic Mie-type resonance by means of femtosecond laser irradiation. This concept is based on ultrafast photoinjection of dense (>1020 cm–3) electron–hole plasma within such nanoparticle, drastically changing its transient dielectric permittivity. This allows manipulation by both electric and magnetic nanoparticle responses, resulting in dramatic changes of its scattering diagram and scattering cross section. We experimentally demonstrate 20% tuning of reflectance of a single silicon nanoparticle by femtosecond laser pulses with wavelength in the vicinity of the magnetic dipole resonance. Such a single-particle nanodevice enables designing of fast and ultracompact optical switchers and modulators.

161 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,403
20223,116
20211,239
20201,571
20191,715
20181,651