MAX IV laboratory (formerly MAX-laboratory) is a Swedish national synchrotron radiation facility located in Lund, Sweden. It currently consists of three electron storage rings, MAX I, MAX II and MAX III that produce synchrotron light to be used in experiments of various fields of science such as physics, chemistry, biology, materials science, geology, engineering and medicine.
MAX II is a 3rd generation storage ring operating at 1.5 GeV energy. The ring produces radiation from UV to soft and hard X-ray region. Currently, most of the experiments performed by the group are done on the soft X-ray beamline I411 on MAX II. The newest storage ring in the MAX IV laboratory is the 3rd generation MAX III, commissioned in 2007 and operating at 700 MeV in the VUV region, and it houses also the Finnish-Estonian (FINEST) branchline of the I3 beamline.
The soft X-ray beamline I411has been operational since January 1999. The beamline uses synchrotron radiation emitted by a high brilliance hybrid undulator. The radiation is very intense and strongly collimated. The beamline has been mainly used for gas phase studies, the useful photon energy range being 40-1500 eV.
The essential part of the beamline is the monochromator that selects a discrete wavelength of the synchrotron radiation to be used in the measurements. I411 is equipped with a modified SX-700 plane grating monochromator manufactured by Zeiss. It has two interchangeable gratings with groove densities of 366 and 1221 1/mm. Focusing to the exit slit of the monochromator after the grating is accomplished by a plane elliptical mirror. The final focusing to the sample position is achieved by a toroidal mirror.
The beamline has been equipped with a very high resolution, angle-resolving electron spectrometer Scienta R4000. A one meter section of the beamline before the permanent end station has also been reserved for users own experiments. Experiments can be performed on atoms, molecules and clusters, vapors, liquids and thin films using photoelectron spectroscopy (XPS), near edge X-ray absorption spectroscopy (NEXAFS), Resonant Raman Auger spectroscopy, time-of-flight ion mass spectroscopy, ion-electron and electron-electron coincidence spectroscopy.
A multipurpose system, built in Oulu, can be used on the one meter section as a time of flight ion mass spectrometer, conventional electron spectrometer, threshold electron spectrometer or coincidence spectrometer between ions and electrons with selected kinetic energies. This setup can be rotated around the photon beam thus allowing angle resolved studies and can be operated either alone or simultaneously with the permanent R4000 end-station.
I3 beamline with FINEST branchline
The source of I3 is an APPLE-II type elliptically polarizing undulator (EPU), that emits light whose polarization state can be varied from left- and right-handed circular polarization to various elliptical polarizations as well as to horizontal and vertical linear polarization. The radiation is both highly collimated and bright.
The desired wavelength is chosen by a 6.65 m off-axis Eagle type normal incidence monochromator manufactured by Bestec GmbH. The monochromator is equipped with five grating holders for optimizing the flux and resolution by choice of coating and groove density. Currently three gratings are mounted: a 2400 l/mm Al/MgF2 coated, 4200 l/mm SiC coated and a 4200 l/mm Pt coated. These three gratings cover the photon energy range of 4.6 – 50 eV exceeding a resolving power of 100 000 throughout the photon energy region.
After the monochromator the radiation passes onto a plane mirror used to compensate for the change in beam position when moving the grating. This mirror is also used as a flip mirror to select between the two branches of the beamline: a permanent angle and spin resolved photoelectron spectroscopy end-station for solid state samples and a branchline for gas and vapor phase user experiments. The gas and vapor phase branch, called FINEST, was designed, funded and commissioned by the Finnish-Estonian consortium consisting of the electron spectroscopy group, the materials science group at the University of Turku and the Institute of Physics in Tartu, Estonia, where the Oulu group was in charge of the design and commisioning.
The FINEST branch consists of a single gold coated toroidal refocusing mirror and an efficient two-stage differential pumping setup allowing very high pressures in the interaction region without affecting the UHV of the beamline. This is crucial for performing high pressure vapor phase studies. The FINEST branchline is ideal for VUV studies of vapor phase atoms, molecules and clusters using such techniques as photoelectron spectroscopy, time-of-flight ion mass spectroscopy, total ion yield absorption spectroscopy, electron-ion coincidence and fluorescence spectroscopy.
Laser setup at MAX IV-lab
For studying excited states of atoms and molecules a special laser system has been set up in 2003 in collaboration with University of Uppsala, Sweden. The laser consists of a 532 nm 10.5 W CW Coherent Verdi V10 used to pump a tunable Coherent 899-29 Ti:Sa ring laser producing IR radiation from 690 nm to 1000 nm with three different sets of optics. The laser output power measures more than 1 W directly after the output.
The laser has been used on various kinds of samples in two-color experiments where the target is first excited using the laser radiation and then ionized with synchrotron radiation. Most common targets for such studies in the group have been atomic alkali metal vapors.
The laser setup is currently located in the facilities of Centre of Microscopy and Nanotechnology, University of Oulu.
For more information about MAX IV-laboratory, visit here.
Last updated: 26.9.2017