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We present experimental results for the ionization of aniline and benzene molecules subjected to intense ultrashort laser pulses. Measured parent molecular ions yields were obtained using a recently developed technique capable of three-dimensional im aging of ion distributions within the focus of a laser beam. By selecting ions originating from the central region of the focus, where the spatial intensity distribution is nearly uniform, volumetric-free intensity-dependent ionization yields were obtained. The measured data revealed a previously unseen resonant-like multiphoton ionization process. Comparison of benzene, aniline and Xe ion yields demonstrate that the observed intensity dependent structures are not due to geometric artifacts in the focus. Finally we attribute the ionization of aniline to a stepwise process going through the pi-sigma^star state which sits 3 photons above the ground state and 2 photons below the continuum.
61 - Quyen N. Hart 2011
Using Chandra imaging spectroscopy and Very Large Array (VLA) L-band radio maps, we have identified radio sources at P_{1.4GHz} >=5x10^{23} W Hz^{-1} and X-ray point sources (XPSs) at L_{0.3-8keV}>=5x10^{42} erg s^{-1} in L>L* galaxies in 12 high-red shift (0.4<z<1.2) clusters of galaxies. The radio galaxies and XPSs in this cluster sample, chosen to be consistent with Coma Cluster progenitors at these redshifts, are compared to those found at low-z analyzed in Hart et al. (2009). Within a projected radius of 1 Mpc of the cluster cores, we find 17 cluster radio galaxies (11 with secure redshifts, including one luminous FR II radio source at z=0.826, and 6 more with host galaxy colors similar to cluster ellipticals). The radio luminosity function (RLF) of the cluster radio galaxies as a fraction of the cluster red sequence (CRS) galaxies reveals significant evolution of this population from high-z to low-z, with higher power radio galaxies situated in lower temperature clusters at earlier epochs. Additionally, there is some evidence that cluster radio galaxies become more centrally concentrated than CRS galaxies with cosmic time. Within this same projected radius, we identify 7 spectroscopically-confirmed cluster XPSs, all with CRS host galaxy colors. Consistent with the results from Martini et al. (2009), we estimate a minimum X-ray active fraction of 1.4+/-0.8% for CRS galaxies in high-z clusters, corresponding to an approximate 10-fold increase from 0.15+/-0.15% at low-z. Although complete redshift information is lacking for several XPSs in z>0.4 cluster fields, the increased numbers and luminosities of the CRS radio galaxies and XPSs suggest a substantial (9-10 fold) increase in the heat injected into high redshift clusters by AGN compared to the present epoch.
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