The main goal of the photoluminescence end station (PLES) is luminescence spectroscopy research under vacuum ultraviolet (VUV) as well as soft X-rays (XUV) excitations. Any materials in solid phase (single crystals, glasses, ceramics, films, powders, etc.) can be studied. The end station consisting of an ultra-high vacuum chamber with a closed-cycle helium cryogenic system provides sample temperatures T = 10 – 300 K. To analyze photoluminescence in the UV to near IR range a Shamrock 0.3 m spectrometer (Andor) equipped with the CCD camera and several photomultiplier detectors is coupled to two optical fibers (working in different spectral ranges), collecting emission from the sample. The possibility to use high-resolution excitation (0.01 nm at 100 nm) in scanning mode and the option of tuneable polarization of the incident light make this beamline very attractive for the field of luminescence studies under VUV and XUV excitations. Additionally to the photoluminescence spectroscopy, the end station can be applied to optical spectroscopy experiments examining the reflection signal from flat samples’ surfaces as well as detecting the transmitted light passing through the samples studied. Advanced experiments which include a combination of synchrotron light and some external light sources (for a pump-probe and a photostimulated spectroscopy) are available also if external light sources are provided by users. VUV spectrometer and VUV detection system intended for the study of the luminescence signals at energies higher than 6 eV (below 200 nm) as well as time-resolved registration system are under development and construction.
- Emission spectra from UV to NIR spectral range (200 – 1100 nm).
- Excitation, absorption and reflection spectra with high resolution in 4.55 -1300 eV spectral range.
- Temperature dependence of optical and luminescence properties down to liquid helium temperature (10 K).
Andor Shamrock (SR-303i) 0.3 m spectrometer equipped with three gratings (300 l/mm) optimized for different spectral regions (300, 500 and 1200 nm blaze, respectively). The Andor Shamrock spectrometer collects luminescence from samples with the aid of a fiber optic cable.
- The Newton CCD camera (Newton DU970P-BVF model from Andor) is suitable for the spectral range of 300-1100 nm.
- The set of Hamamatsu photomultipliers (H8259, H8259-01, and H8259-02 photon counting heads) is intended for the spectral range of 200-900 nm.
- The thermoelectrically cooled infrared NIR PMT Unit H10330B-45 (Hamamatsu) can be used in the spectral range of 950-1350 nm.
- The thermoelectrically cooled hybrid photodetector HPM-100-07C (Becker & Hickl) for time-resolved measurements can be used in the spectral range of 220-850 nm. FWHM of instrument response function is 200 ps in single-bunch operation.
Reflection and transmission detectors:
- Two AXUV-100G diodes mounted in UHV serve as detectors of either transmitted or reflected radiation from the samples in suitable geometry.
Low temperature set-up:
The closed-cycle helium cryostat consists of the ARS DE-204PB cryohead and the ARS-4HW compressor (Advanced Research System). The LakeShore 335 temperature controller allows one to regulate sample temperature in the region of 10 – 300 K.
The cryostat, mounted on a rotational stage, is installed on an XYZ manipulator (Thermionics) facilitating the alignment of the sample with respect to the incident beam. The size (10×2 cm2) of the two-sided sample holder is large enough to accommodate even dozens of samples on each side. The UHV vacuum chamber is evacuated to the working vacuum level of 10-9 mbar at room temperature by a turbo pump HiPace 300 (Pfeiffer Vacuum).
Time-resolved measurements and single-bunch operation
The experimental setup is equipped with a fast detector for time-resolved measurements. In usual operation conditions, the bunch length is ~700 ps and the time window between the bunches is 10 ns. To increase the time window and shorten the excitation pulse duration, single-bunch operation mode of the ring can be requested. In that mode, the bunch length is ~200 ps and time window is 320 ns. Single-bunch operation can be requested for 23 h on Tuesday, which would be the first day of your beam time.
The number of days available for single-bunch operation will be limited, as only two beamlines can utilize this mode of operation. Therefore, it is not guaranteed that all approved proposals will receive a single-bunch operation day even if it was requested. The final decision will be made after beam time scheduling and it will depend on the merits of the proposal, the ring operation schedule and willingness of the other beamlines to allow single-bunch operation on beamline commissioning days.
If you want to request a single-bunch operation day, please check the box “23 h of single-bunch operation” under the selection of the photoluminescence end station during proposal submission in DUO. Please describe in the proposal what you would like to measure during the single-bunch operation and how it will benefit your experiment. Note that since single-bunch operation is not guaranteed, time-resolved measurements cannot be the main point of the proposal.
A whole week (30 shifts) of single-bunch operation will be available to users in the cycle (September 2022 – February 2023). If you want to apply for a beamtime in a single-bunch week, you should indicate that clearly in your beamtime proposal. In that case, the scientific motivation of your proposal should be based on the use of single-bunch operation.