Results 1 - 10 of 10521
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[en] We derive the analytical expression of microcavity-enhanced factor for third harmonic generation in terms of detunings, linewidths, and the Purcell factors of the relevant microcavity modes. It is suitable for microcavities with any dimensions and arbitrary geometric shapes.
[en] We present a study of the core of the Fe Kα emission line at ∼6.4 keV in a sample of type II Seyfert galaxies observed by the Chandra high-energy grating. The sample consists of 29 observations of 10 unique sources. We present measurements of the Fe Kα line parameters with the highest spectral resolution currently available. In particular, we derive the most robust intrinsic line widths for some of the sources in the sample to date. We obtained a weighted mean full width at half-maximum (FWHM) of 2000 ± 160 km s-1 for 8 out of 10 sources (the remaining sources had insufficient signal to noise). From a comparison with the optical emission-line widths obtained from spectropolarimetric observations, we found that the location of Fe Kα line-emitting material is a factor of ∼0.7-11 times the size of the optical broad-line region. Furthermore, compared to 13 type I active galactic nuclei (AGNs) for which the best Fe Kα line FWHM constraints were obtained, we found no difference in the FWHM distribution or the mean FWHM, and this conclusion is independent of the central black hole mass. This result suggests that the bulk of the Fe Kα line emission may originate from a universal region at the same radius with respect to the gravitational radius, ∼3 x 104 rg on average. By examining the correlation between the Fe Kα luminosity and the [O IV] line luminosity, we found a marginal difference in the Fe Kα line flux between type I and type II AGNs, but the spread in the ratio of LFe to L[OIV] is about two orders of magnitude. Our results confirm the theoretical expectation that the Fe Kα emission-line luminosity cannot trivially be used as a proxy of the intrinsic AGN luminosity, unless a detailed comparison of the data with proper models is applied.
[en] In this paper it is shown theoretically and verified experimentally that Fourier transform of 'the Moire fringes visibility formed by two gratings versus gratings' distance provides the spectral line-shape. By this technique, also the wavelength and linewidth can be determined very quickly and with precision much higher than the conventional interferometric methods. The technique is particularly very suitable for rather wide spectral lines
[en] Measurements were made to determine the photocount statistics and photocount correlations of a cw dye laser operated with and without internal etalons to achieve narrow linewidth. In addition, estimates of the mean laser light intensity as a function of time were made from photocount count records and the use of a newly developed stochastic estimation procedure. (U.S.)
[en] We estimate the spreading width of M1 states in Ca isotopes for the purpose of trying to understand the missing strength specially in sup(44) Ca. We do this by means of a doorway calculation, where states explicitly considered have a level of complexity next to the independent-particle M1 state. (author)
[en] The crystallization of metalic glasses METGLAS 2826 and METGLAS 2826A was investigated by ferromagnetic resonance. The line width of the absorption curve first derivative was measured for various isothermic treatment times at 3750C. It was observed that after the reduction atributed to tension relaxation, the line width increases with time treatment. The results suggest that, for suficiently long times, the line width is a function only of the transformed fraction. (A.C.A.S.)
[pt]A cristalizacao dos vidros metalicos METGLAS 2826 e METGLAS 2826A foi investigada por ressonancia ferromagnetica. A largura de linha da primeira derivada da curva de absorcao foi medida para varios tempos de tratamento isotermico a 3750C. Observou-se que apos uma diminuicao, atribuida a relaxacao de tensoes, a largura de linha passa a aumentar com o tempo de tratamento. Os resultados sugerem que, para tempos suficientemente longos, a largura de linha e funcao apenas da fracao transformada. (autor)
[en] Fully sampled degree-scale maps of the 13CO 2-1 and CO 4-3 transitions toward three members of the Lupus Molecular Cloud Complex-Lupus I, III, and IV-trace the column density and temperature of the molecular gas. Comparison with IR extinction maps from the c2d project requires most of the gas to have a temperature of 8-10 K. Estimates of the cloud mass from 13CO emission are roughly consistent with most previous estimates, while the line widths are higher, around 2 km s-1. CO 4-3 emission is found throughout Lupus I, indicating widespread dense gas, and toward Lupus III and IV. Enhanced line widths at the NW end and along the edge of the B 228 ridge in Lupus I, and a coherent velocity gradient across the ridge, are consistent with interaction between the molecular cloud and an expanding H I shell from the Upper-Scorpius subgroup of the Sco-Cen OB Association. Lupus III is dominated by the effects of two HAe/Be stars, and shows no sign of external influence. Slightly warmer gas around the core of Lupus IV and a low line width suggest heating by the Upper-Centaurus-Lupus subgroup of Sco-Cen, without the effects of an H I shell.
[en] The instrumental resolution function for the Daresbury 9.1 high-resolution powder diffractometer has been measured as a function of wavelength, slit width and specimen geometry. It has been demonstrated that the effects of size and strain from the sample of annealed barium fluoride used as a reference material were negligible, and that it is a suitable standard for studying instrumental broadening. The results of considering the angular dependence of the Lorentzian and Gaussian components of the integral breadths of instrumental line profiles are in excellent agreement with those predicted by the receiving-slit width and the known wavelenght spread in the incident beam. The measured instrumental resolution function was found to be dependent on the slit dimensions at low and intermediate angles, and to be dominated by the effects of angular dispersion at higher angles. The line shapes are predominantly Gaussian at low angles and for a flat sample tend to a pure Lorentzian shape at 180deg. The line profiles for a capillary sample are similar at low and intermediate angles and tend to an intermediate Gaussian/Lorentzian form at high angles. (orig.)