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van Der Voort M Rella CW van Der Meer LF Akimov AV Dijkhuis JI 《Physical review letters》2000,84(6):1236-1239
We present results of the first vibrational photon-echo, transient-grating, and temperature dependent transient-bleaching experiments on a-Si:H. Using these techniques, and the infrared light of a free electron laser, the vibrational population decay and phase relaxation of the Si-H stretching mode were investigated. Careful analysis of the data indicates that the vibrational energy relaxes directly into Si-H bending modes and Si phonons, with a distribution of rates determined by the amorphous host. Conversely, the pure dephasing appears to be single exponential, and can be modeled by dephasing via two-phonon interactions. 相似文献
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The rapid and efficient synthesis of various 2,6-disubstituted-3-amino-imidazopyridines using a microwave-assisted one-pot cyclization/Suzuki coupling approach is described. The utility of a 2-aminopyridine-5-boronic acid pinacol ester as a robust and versatile building block for the synthesis of diverse compound libraries is emphasized. The boronate functional group is remarkably tolerant to the Lewis acid catalyzed cyclizations, and the subsequent Pd(0)-catalyzed Suzuki coupling reactions proceed cleanly in the presence of magnesium salts. This work highlights the vast potential of microwave-assisted, metal-catalyzed, multicomponent reactions. 相似文献
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Cormier E Walmsley IA Kosik EM Wyatt AS Corner L Dimauro LF 《Physical review letters》2005,94(3):033905
We propose a method for the complete characterization of attosecond duration electromagnetic pulses produced by high harmonic generation in an atomic gas. Our method is based on self-referencing spectral interferometry of two spectrally sheared extreme ultraviolet pulses, which is achieved by pumping the harmonic source with two sheared optical driving pulses. The resulting interferogram contains sufficient information to completely reconstruct the temporal behavior of the electric field. We demonstrate that such a method is feasible, and outline two possible experimental configurations. 相似文献
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Intense self-compressed, self-phase-stabilized few-cycle pulses at 2 microm from an optical filament
Hauri CP Lopez-Martens RB Blaga CI Schultz KD Cryan J Chirla R Colosimo P Doumy G March AM Roedig C Sistrunk E Tate J Wheeler J Dimauro LF Power EP 《Optics letters》2007,32(7):868-870
We report the compression of intense, carrier-envelope phase stable mid-IR pulses down to few-cycle duration using an optical filament. A filament in xenon gas is formed by using self-phase stabilized 330 microJ 55 fs pulses at 2 microm produced via difference-frequency generation in a Ti:sapphire-pumped optical parametric amplifier. The ultrabroadband 2 microm carrier-wavelength output is self-compressed below 3 optical cycles and has a 270 microJ pulse energy. The self-locked phase offset of the 2 microm difference-frequency field is preserved after filamentation. This is to our knowledge the first experimental realization of pulse compression in optical filaments at mid-IR wavelengths (lambda>0.8 microm). 相似文献
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The Laser-induced fluorescence spectra of ionic cluster C6F6+·Xn, where X = He, Ne, or Ar, are obtained by multiphoton ionization of C6F6 seeded in an inert gas expansion. Spectral information concerning the red-shifts and linewidths of the ionic cluster are reported and observations relevant to their formation mechanisms are offered. 相似文献
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HSPB5 or alpha B-crystallin (CRYAB), originally identified as lens protein, is one of the most widespread and represented of the human small heat shock proteins (sHSPs). It is greatly expressed in tissue with high rates of oxidative metabolism, such as skeletal and cardiac muscles, where HSPB5 dysfunction is associated with a plethora of human diseases. Since HSPB5 has a major role in protecting muscle tissues from the alterations of protein stability (i.e., microfilaments, microtubules, and intermediate filament components), it is not surprising that this sHSP is specifically modulated by exercise. Considering the robust content and the protective function of HSPB5 in striated muscle tissues, as well as its specific response to muscle contraction, it is then realistic to predict a specific role for exercise-induced modulation of HSPB5 in the prevention of muscle diseases caused by protein misfolding. After offering an overview of the current knowledge on HSPB5 structure and function in muscle, this review aims to introduce the reader to the capacity that different exercise modalities have to induce and/or activate HSPB5 to levels sufficient to confer protection, with the potential to prevent or delay skeletal and cardiac muscle disorders. 相似文献