We developed a time-of-fight photoelectron spectrometer that simultaneously analyzes low energy electrons photoemitted from solid surfaces in an energy- and angle-resolved manner. To achieve this, a field free drift tube with an acceptance angle of 22° is combined with two-dimensional position-sensitive detection of photoelectrons, which is realized by a microchannel plate stack and a delay-line anode for position encoding. Here, we present the design considerations and principles of operation including analysis of multiple events per light pulse. The performance of the spectrometer is demonstrated by photoemission from a Cu(111) single crystalline surface by UV femtosecond laser pulses at 6.2 eV photon energy

Optical reflectance of thin adsorbates on solid surfaces is able to reveal fundamental changes of molecular properties compared to bulk systems. The detection of very small changes in the optical reflectance required several technical improvements in the past decades. We present an experimental setup that is capable of high-quality measurements of submonolayers and ultrathin layers of photochromic molecules on surfaces as well as quantifying their isomerization kinetics. By using photomultipliers as detectors, an enhancement of the signal-to-noise ratio by a factor of three with a total reduction of light exposure on the sample by at least four orders of magnitude is achieved. The potential of the experimental setup is demonstrated by a characterization of the photoswitching and thermal switching of a spirooxazine derivate on a bismuth surface.