Understanding magnetization dynamics on a small spatial and a fast temporal scales is of both fundamental and technological interest, as future magneto-electronic devices are getting smaller and faster down to a few tens of nanometer and a few hundreds of picosecond. On ps time scale the magnetization dynamics is determined by the fundamental spin processes of precession and damping whose microscopic origins are not well understood yet. For a time and spatially resolved microscopy technique, we have utilized the high spatial resolution Photoemission Electron Microscope PEEM-2 at the ALS and the intrinsic time resolution given by the ALS pulse width. The first observation results of x-ray magnetic microscopy on the 100 ps time scale and 100 nm length scale will be reported here. The ps time resolution was achieved by utilizing a pump-probe technique via synchronization between femtosecond laser pump for short magnetic pulse generation and ALS synchrotron x-ray probe for x-ray microscopy observation. Magnetic field pulse was created by current pulse, launched from a photoconductive switch through a lithographically produced waveguide structure. The switch was triggered by a fs laser, synchronized to the pulse train of the ALS, operated in two bunch mode. The fast evolution of magnetic domains was monitored as a function of the delay between the magnetic field pulse (pump) and the x-ray pulse (probe) using a stroboscopic pump-probe setup. The time resolved magnetization evolution images were analyzed within the context of micromagnetic consideration using the magnetic pulse profile, which was determined independently by utilizing the deflection of images due to the time dependent electric potential while current pulse flows through the waveguide.

Typically the performance of Photoemission Electron Microscopes (PEEM) is reported as one number, representative of amicroscope's ultimate performance under an ideal set of conditions. Often a simple Rayleigh criterion is used which definesthe spatial resolution approximately as the minimum distance of two still distinguishable features. However, the ability of aninstrument to provide meaningful spectroscopic and microscopic information depends on the contrast loss of a pattern over amuch wider range of spatial frequencies. For example, the chemical signature of one area on the sample can be contaminated from an adjacent area although both areas are still easily distinguishable in a microscopic image. We report here on a morecomprehensive measurement of the PEEM-II instrument at the Advanced Light Source that examines the response of the instrument to a wide range of experimental conditions and compares this response to both analytic and computer models of the expected performance. The absolute magnification, the transmission as a function of the four interchangeable energy and angular filtering apertures, and modulation transfer functions which describe the performance of the instrument over a range of spatial frequencies from unity to the performance limit were obtained at an experimentally relevant range of operating voltages. The results are both useful to current and future users of the instrument in determining what scientific questions canand cannot be answered with the apparatus, and after comparison with previously published analytic results and new computer ray tracing simulations of the instrument highly valuable to the efforts in next generation PEEM realization.

Nano-roughness is one of the major factors degrading the emittance of electron beams that can be generated by high efficiency photocathodes, such as the thermally reacted alkali antimonide thin films. In this paper, we demonstrate a co-deposition based method for producing alkali antimonide cathodes that produce near atomic smoothness with high reproducibility. We calculate the effect of the surface roughness on the emittance and show that such smooth cathode surfaces are essential for operation of alkali antimonide cathodes in high field, low emittance radio frequency electron guns and to obtain ultracold electrons for ultrafast electron diffraction applications.

The advent of fully coherent free-electron laser and diffraction-limited synchrotron radiation storage ring sources of x-rays is catalyzing the development of new ultrahigh accuracy metrology methods. To fully exploit these sources, metrology needs to be capable of determining the figure of an optical element with subnanometer height accuracy. The major limiting factors of the current absolute accuracy of ex situ metrology are drift errors due to temporal instabilities of the lab's environmental conditions and systematic errors inherent to the metrology instruments. Here, we discuss in detail work at the Advanced Light Source X-Ray Optics Laboratory on building of advanced environmental control that is a key component in the development of ultrahigh accuracy ex situ metrology for x-ray optics. By a few examples, we show how the improvement of the environmental conditions in the lab allows us to significantly gain efficiency in performing ex situ metrology with high-quality x-ray mirrors. The developed concepts and approaches, included in the design of the new X-Ray Optics Laboratory, are described in detail. These data are essential for construction and successful operation of a modern metrology facility for x-ray optics, as well as high-precision measurements in many fields of experimental physics.