Nuclear forward scattering of synchrotron radiation.
Nuclear forward scattering of synchrotron radiation.
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同步加速器辐射的核前向散射。
DOI：
10.1103/physrevb.46.6207
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
R. Hollatz
中科院分区：
文献类型：
--
作者：
U. V. Bürck;D. Siddons;Jerome B. Hastings;Uwe Bergmann;R. Hollatz
用同步辐射激发多晶$^{57}\ mathm {Fe}$箔的M′′ossbauer跃迁后，测量了正向相干核再发射。激发的共振在能量上足够窄，可以直接观察到它们衰变的时间依赖性，特别是可以研究对单光子激发的集体响应的细节。当薄膜厚度在0.5 ~ 28.5 μ m之间时，集体核散射条件在较大范围内直接变化。随着箔厚度的增加，时间演化的包络线呈现出明显的变化。对于薄箔（厚度达3 \ensuremath{\mu}m），包络线在观测时间窗内呈指数型变化，衰减时间随着箔厚度的增加而减小。对于较厚的箔，可以观察到包络的振荡调制和拍型相位的显著移位。一个简单的光学模型可以解释所有观测到的现象。
The coherent nuclear reemission in the forward direction has been measured following excitation of the M\"ossbauer transitions in polycrystalline $^{57}\mathrm{Fe}$ foils by synchrotron radiation. The excited resonances are sufficiently narrow in energy that the time dependence of their decay can be straightforwardly observed, and in particular the details of the collective response to single-photon excitation can be studied. The collective nuclear scattering conditions were varied directly over a large range by using foil thicknesses between 0.5 and 28.5 \ensuremath{\mu}m. The envelope of the time evolution showed significant changes with increasing foil thickness. For thin foils (up to 3 \ensuremath{\mu}m) the envelope was exponential in the observed time window, with a decay time decreasing with increasing foil thickness. For thicker foils an oscillatory modulation of the envelope and a significant shift in the phase of the beat pattern were observed. A simple optical model can explain all the observed phenomena.