Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany.
1] Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany [2] Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, D-14476 Potsdam, Germany.
Nat Commun. 2014 May 30;5:4010. doi: 10.1038/ncomms5010.
Synchrotron radiation facilities routinely operate in a multi-bunch regime, but applications relying on time-of-flight schemes require single bunch operation. Here we show that pulse picking by resonant excitation in a storage ring creates in addition to the multi-bunch operation a distinct and separable single bunch soft X-ray source. It has variable polarization, a photon flux of up to 10(7)-10(9) ph s(-1)/0.1%BW at purity values of 10(4)-10(2) and a repetition rate of 1.25 MHz. The quasi-resonant excitation of incoherent betatron oscillations of electrons allows horizontal pulse separation at variable (also circular) polarization accessible for both, regular 30 ps pulses and ultrashort pulses of 2-3 ps duration. Combined with a new generation of angularly resolving electron spectrometers this creates unique opportunities for time-resolved photoemission studies as confirmed by time-of-flight spectra. Our pulse picking scheme is particularly suited for surface physics at diffraction-limited light sources promising ultimate spectral resolution.
同步辐射设施通常在多束流模式下运行，但依赖飞行时间方案的应用需要单束流操作。在这里，我们展示了在存储环中通过共振激发进行脉冲选择，除了多束流操作之外，还会产生一个独特且可分离的单束流软 X 射线源。它具有可变的偏振性，在纯度值为 10(4)-10(2)时，光子通量高达 10(7)-10(9)ph s(-1)/0.1%BW，重复率为 1.25MHz。电子非相干 betatron 振荡的准共振激发允许在可变（也可以是圆形）偏振下进行水平脉冲分离，这对常规的 30ps 脉冲和 2-3ps 持续时间的超短脉冲都是可用的。结合新一代角度分辨电子谱仪，这为时间分辨光发射研究创造了独特的机会，这一点已经通过飞行时间谱得到了证实。我们的脉冲选择方案特别适合于在衍射极限光源下进行表面物理研究，有望实现最终的光谱分辨率。
