The BACH beamline (Beamline for Advanced diCHroism) is an undulator beamline of the Istituto Officina dei Materiali-Consiglio Nazionale delle Ricerche, which operates at Elettra, in close collaboration with Elettra-Sincrotrone Trieste S.C.p.A.. The beamline offers a multi-spectroscopy approach for the investigation of the electronic, chemical, structural, magnetic and dynamical properties of solid surfaces, interfaces, thin films and solid samples in the UV-soft x-ray photon energy range (44-1650 eV) with selectable light polarization (linear horizontal and vertical, circular), high resolving power (20000-6000) and time resolution (70 psec). Each UHV endstation has a UHV connected preparation chamber for sample growth and surface preparations (sputtering, annealing, evaporators for organics and metals, LEED, mass analyser, leak valves for gas exposures...) and a quick UHV connected sample transfer load lock. In the load lock, exposures up to 100 torr of selected gas and sample heating up to 1000 K can be performed.
The experimental setup of the BRANCHA can also combine Laser and Synchrotron Radiation (SR) in order to study the dynamics of the photo-induced excited states of electronic and magnetic systems with pump-probe time-resolved XAS. Elettra Synchrotron radiation source provide radiation pulse widths sufficiently short to investigate dynamic processes in the time between 70 ps up to 0.5 μs. Typically, optical excitation of the sample is done by laser pulses (synchronized to either hybrid or multi bunch SR pulses), and probing is performed by time-delayed synchrotron radiation pulses.
An hemispherical analyser with vertical entrance slit and 2D detector offers the possibility to perform polarisation dependent soft-x ray ARPES and VUV ARPES in the full range of the beamline (44-1650 eV) on in situ prepared samples.
Sample holders for UHV compatible fluorescence yield XAS in liquid environment are available upon preliminary request.
Recently an in-operando soft-x-ray XAS set up has been implemented at BACH to bridge the “pressure gap” between UHV and ambient pressure, based on the confinement of liquids in a cell with a window separating the fluid from the UHV. One of the end-stations has been dedicated to experiments based on electron transfer processes at the solid/liquid interfaces and during photocatalytic or electrochemical reactions. Suitable cells to perform soft x-ray spectroscopy in the presence of liquids were developed: static cells to study the solid/liquid interface of catalysts in the presence of an electrolyte both in total electron yield (TEY) and fluorescence yield (TFY), and an electrochemical flow cell which allows to carry out in situ cyclic voltammetry, electrodeposition on a working electrode (WE) and to study chemical reactions in-operando conditions and under selected applied voltages.
Endstations and experimental techniques
ENDSTATION A:XPS/UPS,VUV and soft x-ray ARPES,RESPES, RES-ARPES, CIS, Photoelectron Diffraction, fast XPS (ms), XAS (TEY,PEY,TFY,PFY),XLD, in remanence XMCD, XES, Time resolved laser pump-probe XAS (ps) 50-100 K to 800 K + UHV Preparation Chamber
ENDSTATION B: in-operando soft-x-ray XAS set up (at the solid/liquid interfaces and during photocatalytic or electrochemical reactions)
BRANCHLINE C: available for user endstations
0.35 [eV] @ 1650 [eV]
0.025 [eV] @ 500 [eV]
1.5 * 104 [E/deltaE] @ 530 [eV]
1.2 * 104 [E/deltaE] @ 400 [eV]
1.2 * 104 [E/deltaE] @ 90 [eV]
1.6 * 104 [E/deltaE] @ 50 [eV]
5.5 * 103 [E/deltaE] @ 1650 [eV]
2 * 1011 [ph/s] @ 1000 [eV]
6 * 1011 [ph/s] @ 1500 [eV]
25 - 350 [um]
High Energy Undulator
Low Energy Undulator
Monochromator BACH
6600 [E/deltaE] @ 867 [eV]
Cryomagnet 6T XMCD
XAS (X-ray Absorption Spectroscopy) in total eletron yield (drain current) and total fluorescence yield (photodiode), XMCD (X-ray Magnetic Circular Dichroism) and X(M)LD [X-ray (Magnetic) Linear Dichroism] under high magnetic fields (superconducting magnet) and at variable temperature 1.8 K-340 K. Optical ports for laser in-laser out. A surface preparation and sample growth facility is in preparation. UHV environment.
-6.5 to +6.5 Tesla superconducting magnet
1.8 K-340 K cryostat
Sample
Multispectroscopy XPS/ARPES/XAS/XES
temperature down to 50 K possible with LHe cooling). Optical ports for laser in-laser out. UHV environment. Currently used also for pump-probe time resolved XAS in total fluorescence yield. Sample cell for fluoresce yield measurements in liquid environment.
2) ComIXS fluorescence spectrometer with grating for x-ray emission spectroscopy and partial fluorescence yield spectroscopy and medium resolution (~1 eV at 800 eV)- (ask if operative)
3) Channeltron and MCP (ask if available/installed)
4) Keithleys (428 and 6430) for drain current x-ray absorption spectroscopy
5) Ultrafast MCP for total fluorescence yield time-resolved x-ray absorption spectroscopy
Drain Current
Sample
Techniques usage
http://www.elettra.trieste.it/lightsources/elettra/elettra-beamlines/bach/bach-endstations/page-8.html?showall=
Energy dependent ARPES with automatic control of the energy in the sequence
Energy resolution better that 3 meV and angular resolution better than 0.5°, quick acquisition mode to perform fast photoemission with 300 msec total acquisition time per spectrum
http://www.elettra.trieste.it/lightsources/elettra/elettra-beamlines/bach/scienta3000.html
Energy dependent measurements with automatic control of the energy in the sequence
Work function measurements.
Resonant photoemission or energy dependent measurements with automatic control of the energy in the sequence.
Temperature-programmed XPS.
Quick acquisition mode to perform fast photoemission with 300 msec total acquisition time per spectrum
Manipulator or Sample stage
One is a LHe cryostat with 4 degrees of freedom. Its main features are the following:
X-Y (horizontal) travel = ±25 mm; Z (vertical) travel = 200 mm; Angular rotation (polar) = ±180°
Temperature range: 50 K (LHe) or 110 K (LN2)÷1300 K; The minimum temperature depends on the sample holder which is used. For instance using the new VG XL25HC sample holder with PBN and thermoucouple we have reached -4.3 mV on the sample (~100 K).
The temperature range is 250÷1500 K with home-made sample holders, for Si, SiC and Ge.
The other manipulator is a 5-degrees of freedom Omniax manipulator made by VG. This manipulator is currently offline without azimuth. We recommend prospective users to contact the beamline staff if they are interested to use the 5-axis Omniax instead of the Createc on the branch line A. Its main features are the following:
X-Y (horizontal) travel = ±25 mm; Z (vertical) travel = 200 mm; Angular rotation (polar and azimuthal) = ±180°;IMPORTANT NOTICE: Azimuthal rotation is not available at BACH now
Temperature range of the 5-degrees of freedom Omniax: 130÷1000 K (with XL25HC sample holder);
Sample Environment
Sample Holders
Large area (~3 cm) to host several samples at the same time.
Transferable from different chambers.
Quick sample transfer from air to UHV
Thermoucouple can be fixed in contact with the sample
It can be used for temperature programmed XPS
Large area (~3 cm) to host several samples at the same time.
Transferable from different chambers.
Quick sample transfer from air to UHV
Thermocouple can be fixed in contact with the sample
It can be used for temperature programmed XPS
Preparation Chamber
Scraper - diamond file / cleaver
Ar+/Ne+ ion sputtering system
1 Leak Valve
2-degree-of-freedom (theta, z) manipulator (continuous annealing up to 700 K, flash up to 1400 K)
Electro Magnet for in-plane magnetization at room temperature from 0 to 1 kGauss
Ports for user evaporators, including a retractable port with gate valve for fast mounting
Pressure gauge and Residual Gas Analyser . p<3x10-10 mbar
Sample
Time-resolved XAS
Scienta3000 Electron Analyser
fast MCP
Drain Current
Sample
ComIXS Fluorescence Spectrometer
Detection
Drain Current
Detection
fast MCP
Detection
Scienta3000 Electron Analyser
Detection
- NEXAFS
- Time-resolved studies
- XMCD
- X-ray fluorescence (XRF)
- Angular Resolved PES
- Photoelectron diffraction
- Time-resolved studies
- UPS
- XPS
- Inelastic scattering
- Other - Earth Sciences & Environment
- Other - Energy
- Sustainable energy systems
- Knowledge based multifunctional materials
- Other - Material Sciences
- Labview (for XAS/XMCD/XES/time resolved XAS) and SES for Scienta3000 (XPS)
- spectra and images
- ascii, txt, pxp, bin, Igor format
- in-house developed Igor Pro procedures and in-house developed Labview procedures, KolXPD
Users are not allowed bringing any chemical, or any sample, or any instrument at the beamline without any written authorisation of BACH scientists and spp@elettra.eu
