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This article reviews photoemission experiments that simultaneously resolve at least two of the following degrees of freedom: space (real and momentum space), time (intrinsic time scale of a fast experiment or time-of-flight) and spin. In the spatiotemporal domain, imaging of fast processes by PEEM gives direct insight into plasmon dynamics or magnetization processes. In the category real space & spin the novel concept of imaging spin filters is discussed. In the time & spin chapter we address time-of-flight spin detectors and ultrafast spin processes that are accessible by pump-and-probe techniques. A main part of the paper is devoted to the resolution of momentum-space & time. This is implemented in form of the time-of-flight momentum microscope, a very recent development of which the first instrument has been in operation since 2014. In an extended outlook chapter, the potential of new developments and of a novel, highly parallelized delay-line type electron detector will be discussed. The combination of all three degrees of freedom k-space, time & spin is emerging through the combination of the ToF momentum microscope with imaging spin filter. [ABSTRACT FROM AUTHOR]

Photoemission electron microscopy (PEEM) is widely used for the study of magnetic surfaces and thin films. Ferromagnetic and antiferromagnetic microstructures are investigated exploiting magnetic circular and linear dichroism in the soft X-ray range using tuneable synchrotron radiation. Local dichroism spectroscopy gives access to magnetic moments of the elements in compounds or multilayer materials. Beyond these achievements, the method bears a high future potential with respect to an increased lateral resolution via aberration correction of the electron optics and a high time resolution in the 100 ps range for the study of dynamic processes. In addition, photoelectron spin polarisation analysis implemented into PEEM provides a novel local probe for the investigation of spin dynamics. The current instrumental state-of-the-art and the future potential of PEEM in the field of surface and thin-film magnetism are discussed and illustrated by recent examples. [Copyright &y& Elsevier]

A novel design of high-voltage compatible polarimeter for spin-resolved hard X-ray photoelectron spectroscopy (Spin-HAXPES) went into operation at beamline BL09XU of SPring-8 in Hyogo, Japan. The detector is based on the well-established principle of electron diffraction from a W(001) single-crystal at a scattering energy of 103.5 eV. It's special feature is that it can be operated at a high negative bias potential up to 10 kV, necessary to access the HAXPES range. The polarimeter is operated behind a large hemispherical analyzer (Scienta R-4000). It was optimized for high transmission of the transfer optics. A delay-line detector (20 mm dia.) is positioned at the exit plane of the analyzer enabling conventional multichannel intensity spectroscopy simultaneously with single-channel spin analysis. The performance of the combined setup is demonstrated by the spin-resolved data for the valence-region of a FeCo functional layer of a tunneling device, buried beneath 3 nm of oxidic material. The well-structured spin polarization spectrum validates Spin-HAXPES in the valence energy range as powerful method for bulk electronic structure analysis. The spin polarization spectrum exhibits a rich structure, originating from clearly discernible transitions in the majority and minority partial spin spectra. [ABSTRACT FROM AUTHOR]

Abstract: The present work enlightens the developments in time- and energy resolved photoemission electron microscopy over the past few years. We describe basic principles of the technique and demonstrate different applications. An energy- and time-filtering photoemission electron microscopy (PEEM) for real-time spectroscopic imaging can be realized either by a retarding field or hemispherical energy analyzer or by using time-of-flight optics with a delay line detector. The latter method has the advantage of no data loss at all as all randomly incoming particles are measured not only by position but also by time. This is of particular interest for pump–probe experiments in the femtosecond and attosecond time scale where space charge processes drastically limit the maximum number of photoemitted electrons per laser pulse. This work focuses particularly on time-of-flight analysis using a novel delay line detector. Time and energy resolved PEEM instruments with delay line detectors enable 4D imaging (x, y, Δt, E Kin) on a true counting basis. This allows a broad range of applications from real-time observation of dynamic phenomena at surfaces to fs time-of-flight spectro-microscopy and even aberration correction. By now, these time-of-flight analysis instruments achieve intrinsic time resolutions of 108ps absolute and 13.5ps relative. Very high permanent measurement speeds of more than 4 million events per second in random detection regimes have been realized using a standard USB2.0 interface. By means of this performance, the time-resolved PEEM technique enables to display evolutions of spatially resolved (<25nm) and temporal sliced images life on any modern computer. The method allows dynamics investigations of variable electrical, magnetic, and optical near fields at surfaces and great prospects in dynamical adaptive photoelectron optics. For dynamical processes in the ps time scale such as magnetic domain wall movements, the time resolution of the delay line detectors even allows to be used directly for real-time experiments as well. [Copyright &y& Elsevier]

The interaction of intense, pulsed laser radiation with surfaces results in non-linear optical effects that are responsible for emission of electrons even if the photon energies are below the work function. In the present study, photoelectrons have been excited by means of femtosecond laser pulses from a frequency doubled Ti:sapphire laser with a photon energy of 3.1 eV. The spatial distribution of the photo emitted electrons was imaged using a photoemission electron microscope. All samples exhibit centres of enhanced second or higher order photoemission yield, so called ‘hot spots’. These ‘hot spots’ were preferentially excited with s-polarised light. This behaviour may be explained on the basis of a microscopic model assuming localised plasmon excitations in small particles. Lead films and pentacene layers adsorbed on silicon have been studied. The photoelectron yield depends strongly on the sample topography and the polarisation of the photons. The polarisation and power dependence of the multi-photon photoemission yield were studied. Clear evidence for three-photon contributions has been found although two-photon photoemission is sufficient to overcome the surface barrier. [Copyright &y& Elsevier]