The group's Oulu laboratory hosts materials research infrastructure for studying the electronic properties and interactions from atomic and molecular vapors to free unsupported nanostructures as well as condenced phase of matter. Most of the equipment is custom engineered and manufactured and/or tailored to provide best accuracy possible for users in Oulu laboratory and in international radiation source facilities. With instruments in Oulu, the group can perform test measurements and experiment development before entering a beamtime at synchrotron radiation facilities. A crucial function of the laboratory in Oulu is also to train the masters and PhD students to the experimental work.
Some examples of the experimental setups
Electron and ion spectrometers
The group has two hemispherical analysers made by VG Scienta (SES100 and SES200) which are suited for measuring electron kinetic energies with high resolution. Either of these can also be used as part of an electron-ion coincidence setup where ions are detected using a selfmade Wiley-McLaren type time-of-flight spectrometer with position sensitive detector.
The group is currently building a magnetic bottle-type electron spectrometer which benefits from electron collection efficiency several times higher than in hemispherical analysers. This can be utilised for example with detection of rare ionisation processes or with low sample densities, both of which suffer from low signal. The instrument is also designed to be used in the FinEstBeaMS beamline (MAX IV Laboratory, Lund, Sweden).
Laboratory Excitation Sources
- Specs UVS 300 source: He I radiation (21.2 eV) for studies of valence photoelectron spectra of various samples.
- X-ray tube: Equipped with Al and Mg anodes.
Exchange Metal Cluster Source (EXMEC)
Capable of producing of free, neutral and size varied metal-, semiconductor- and molecular nanoclusters in the size range from few tens to thousands of atoms/cluster. For more information, see here.
Andor SR-500 spectrograph can be used to measure emitted light from de-excitation of atoms and molecules for wavelenghts between 300-1200 nm with < 0.1nm resolution. With the aid of extended fiber optic cables one can do measurements even in industrial/harsh conditions with easily transportable setup.
For producing vapors from solid samples one needs an oven. The group has long traditions in manufacturing and designing different types of ovens for vapor production and currently two types of ovens are used in the experiments:
- Resistively heated ovens: For low- and intermediate temperature ranges.
- Inductively heated ovens: For high temperature metals and semimetals.
The existing multistage ovens enable also the dissosiative preparation of multimers and/or single molecules prior to probing their properties. The newly developed simultaneous solid state & vapor phase oven design provides new insight into the calibration of the absolute binding energies in solid state.
Electron impact spectroscopy
In order to create deep core-hole states and to follow their Auger decay and various cascade processes, also charged particles, such as electrons, have been used for primary ionization. The spectra created by electron impact have been recorded with the SES-200 electron energy analyzer in the Oulu laboratory.
Electron energy loss spectroscopy (EELS)
Detecting the elastically and inelastically scattered electrons from primary electron beam and recording the energy loss of the electrons can be used as a tool for studying both valence and core excitations of the target. The EELS method can be used as an analogue to the photon absorption experiments or, under certain conditions (large scattering angles, low energy), and for studying dipole- and spin-forbidden transitions. For EELS experiments a special setup has been designed in Oulu, where the Scienta SES-100 analyzer is used in a reversed mode as an electron energy monochromator and the SES-200 as an electron energy analyzer.
Electron optical calculations for further development of the electron spectrometers and ion time-of-flight analyzers are also an important part of research in Oulu.
For studying excited states of atoms and molecules a special laser system was set up in 2003 in collaboration with University of Uppsala to MAX lab (Currently: MAX IV Laboratory, Lund, 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.
Last updated: 11.10.2017