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The Endstations

In the UHV endstation of the BRANCH A it is possible to perform a multi-spectroscopy investigation with photoemission (including ARPES), x-ray absorption (TEY,PEY,TFY,PFY), x-ray emission and x-ray magnetic circular dichroism in remanence.   A LEED and several electron beam evaporators are available to deposit  selected metals on the sample surface at different temperatures (50 K-750 K).

A SAMPLE-PREPARATION UHV chamber, directly connected to the Endstation A can be used to grow thin films of metals or metal oxides and deposit organic/inorganic molecules, hybrid systems or magnetic elements on solid surfaces.

This endstation is  OPEN TO USERS

The experimental setup of the BRANCH B hosts a new endstation dedicated to x-ray magnetic circular dichroism in high magnetic fields (± 6.5 Tesla) along the beam and variable tempertaure from 1.9 K to 340 K on the sample in a base pressure of 4x10-11 mbar.  A surface preparation chamber will be available soon for the investigations of the magnetic propertis of in situ grown samples. 

This endstation is NOT 
OPEN TO USERS

 

 

The experimental setup of the BRANCH A 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 x-ray absorption spectroscopy. 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.
 
Time resolved XAS setup is OPEN TO USERS!

A third BRANCH C is also available for the installation of user endstations for long term projects. 


Endstation A

This endstation is located at the end of the branch A where the spot dimensions on the sample are about 300x20 micron2: this permits the utilization of the photon spectrometer for x-ray emission experiments. For photoemission the spot dimensions are set to 300x200 micron2. The endstation A of BACH is divided in two different parts: the Main experimental and the Preparation chamber. They are connected through a nipple that let the transfer of the prepared sample into the experimental chamber. Both the chambers include also a sputtering system to prepare the sample surfaces.

Lateral View

Top View

3-Dimensional and top view of the BACH endstation (experimental + preparation chambers). The arrows indicate the flanges on which the various instruments and devices are mounted. The red arrow indicate the monochromatized photon beam delivered by the beamline. The white cross at the right side (in the top view) represents a 6-way cross on which the following elements are mounted: transfer arm, scraper, load lock, window.



The Main Chamber of the Endstation A

INSTRUMENT STATUS/NOTES
Electron analyzer: SCIENTA R3000.new nook OK
The Electron Analyser is at 60° from the incident photon beam, in the horizontal plane
ComIXS x-ray fluorescence spectrometer; OK
The Fluorescence Spectrometer is at -60° from the incident photon beam, in the horizontal plane
Femptoamp meter for total yield x-ray absorption measurements (Keithley);
Two (Keithley Electrometer 6430). 
OK
Also two 6514 Keithley Electrometers and two Keithley Amplifier 428 are available.
These instruments can be connected via PCI and/or GPIB interface with the PC that controls the entire beamline and they can collect signals coming from the mirror surfaces or a freshly evaporated gold mesh, the intensity read on some photodiodes, the drain current from the sample and the electron analyzer counts.
Channeltronnew nook OK
Si photodiode For Total Fluorescence Yield measurements only for very insulating samples
VG Rear View with 8011 Electronics OK
Works down to low energies (~15-25 eV).
Retraction not working (LEED has been twisted)
Retractable LEED (OCI) Offline. It is currently in for repair.
He lamp: SPECS UV-Source UVS 300 Offline
Manipulator (x,y,z and theta) (CREATEC) OK

LHe cryostat: from 30 K to about 1500 K

 

OK
The minimum temperature on the sampe holder is 50 K using LHe, 130 K using LN2;
Pressure gauge and Residual Gas Analyser OK (p<3x10-10 mbar)
Ar sputtering gun (VG) OK. Only filament 2 is working.
gas line for surface preparations in UHV; 2 leak valves O2, H2, CO are availabe.
For other gases, please contact us
single e-beam evaporator (Omicron) Fe
triple e-beam evaporator (Omicron) channel1: Si rod (OK? installed sep11)
channel2:Mn basket (OK)
channel3: Ti rod (filament maybe not working)
sample scraping device OK
Mg/Al Kalpha X-Ray source new nook Just installed (Sept 2011). To be tested
working disatnce: 1-2 cm
Fast entry Load Lock OK

 



The Prep Chamber of the Endstation A

Prep chamber Instrument Status
crystal cleaver OK
Scraper/Cleaver OK
Ar+ ion sputtering system OK
1 Leak Valve OK
2-degree-of-freedom (theta, z) manipulator (continuous annealing up to 700 K, flash up to 1000 or 1500 K) OK
Electro Magnet for in-plane magnetization at room temperature OK
User evaporators (e.g. organic molecules) OK
Pressure gauge and Residual Gas Analyser OK. p<3x10-10 mbar


The sample manipulators


In the Main chamber , the sample manipulator is mounted vertically on top of the experimental chamber. In the Main chamber two manipulators are available.
  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: 30 K (LHe) or 90 K (LN2)÷1000 K; IMPORTANT: This manipulator is currently not available (May 2009) because it is in repair. The present manipulator installed on the BACH endstation is get on load from Universita' Cattolica di Brescia. It is a CREATEC LHe cryostat with 4 degrees of freedom (XYZpolar). The minimum temperature of this manipulator is 30 or 50  K with LHe and 100-110 K with LN2 on the sample holder. 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.
IMPORTANT: If you need to flash your sample above 1000 K, please contact the beamline

The other manipulator is a 5-degrees of freedom Omniax manipulator made by VG. This manipulator is currently installed on the branch B for time resolved XAS (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);


In the Preparation chamber we have an home-made manipulator (the so called "garage") which can host up to three sample carriers and which can be used for parking the samples in UHV or anneal the samples with direct current up to 10 Amp or using a PBN (up to ~700-800 degree Celsius). Annealing is possible also during the evaporation.

The sample holders


There are several sample carriers: standard VG (XL25VH and XL25HC) and home-made carriers for heating by filament for radiative sample heating (up to 300° C) or electron bombardment (available only under special requests) or direct current flow (max 10 Amp, sample always grounded).
For dimensions and further information on the sample holders please download the pdf from the VG-Scienta website:

PDF FILE (Standard VG Sample Holder)

Note: The maximum current which can be applied in continuous is 1.2 A!


The samples

The Samples must be conductive for photoemission measurements. The sample holder can host one or more samples in a square area of about 25x25 mm. The samples can be fixed by conductive UHV compatible glue, UHV-compatible carbon/copper tape, by Mo clamps (up to 4), or it can be sandwiched between the sample holder body and a Mo/Stainless steel cap with one hole of different sizes and shapes. For Si, Ge and SiC the sample should be cut in a rectangular piece (IDEAL: 3.5 mm x 8 mm. However, it can fit also 3-4 mm x 7-9 mm).

 

 

IMPORTANT INFORMATION FOR IN-SITU SAMPLE PREPARATION! If the sample needs to be prepared in situ, the sample must be sent to the contact person at the BACH beamline, arranging the delivery so that they can be mounted and transferred in the preparation chamber at least 10 days before the experimental run in order to properly degass the sample holder. When annealing is required, the sample will be typically holded between two plates (one below and one above, with one hole of the proper size and shape to hold the sample). Please specify if there is incompatibility (e.g. alloy formation during annealing) with any material possibly used for the sample holder plate. We typically use: Mo or stainless steel. If you have special requests please contact your local contact well in advace and if necessary provide a 0.1-0.125 mm plate of the material.
 


Evaporation

.:. Evaporation Conditions for Gold MBE, Mn MBE, Omicron e- Beam Manual
    • Omicron Triple Evaporation Source EFM3T (Currently installed on the MAIN chamber, available for special requests and ONLY to collaborators)

    • Omicron Single Evaporation Source EFM (Currently installed on the MAIN chamber, available for special requests and ONLY to collaborators)

    • 2 MBE Komponenten High Temperature Effusion Cell MTEZ 40-1.5 (Currenly already in use, not available for users)

    • 2M Tricon Electron Bombardment Evaporation Source (Available only for special requests)

    • 2 Custom-made evaporators (POWER FEEDTHROUGH 5KV 30AMP x PIN, MAX 120AMP ALL PIN LOADED,PIN DIAMETER 2,38mm, 4PIN COPPER ON CF40), lenght of the rods: 34 mm and 35 mm. This evaporator can be used only for low-temperature evaporation (up to about 400° C), since there is no water cooling system). They are mounted with a linear transfer with 40-100 mm shift. E.g. In the CF35 flange pointing upwards there is a linear transfer whose lenght is 8 cm fully extended and 4 cm fully contracted. This lengh allows to reach the sample in the preparation chamber. The same dimensions can be used by the users to make their evaporators planned for BACH beamtime. The evaporation material can be hosted in 0.05 mm folded Ta foil, or a custom/commercial made basket or boat.

  • In the Preparation experimental chamber, several flanges can host e-beam, MBE or home-made evaporators.
    In particular, for evaporation during sample annealing (T=300 K to 780 K) there are 3 flanges CF35 flanges (not CF40) pointing upwards (distance flange-sample about 31 cm), 1 CF38 flange pointing downwards. For evaporation at T=300 K there are 1 CF38 flange horizonatal (distance flange-sample about 25 cm) and one CF100 flange horizontal (distance flange-sample about 25 cm).
  • In the Main chamber we have 2 CF38 ports where up to 2 e-beam evaporators (e.g. a Single or Triple Omicron EMF 3, Tricon, Elmitec) can be installed.
  • The following metals can be evaporated by e-beam: Fe, Co, Ni, Ti, Mn, Ge, Si (materials already tested), Cr, Au, Ag, Cu, Pb, Pd, Pt, Rh, some Lanthanides. If you need to evaporate volatile elements such as thiols, Ga, As, Sb, Sn, Na, organo-metallics and polymers you should contact the beamline scientist/local contact, in order to check the feasibility and arrange the experiment, well in advance before the experiment. In any case we do NOT allow the evaporation of organic molecules and volatile elements in the Main Chamber (please consider that the LEED has no shutter and there are very delicate optical elements and instrumentation).
  • The users are strongly reccomended to provide us THEIR OWN evaporators for the experiment, well in advance before the experiment. The evaporators must be sent to the contact person at BACH beamline, arranging the delivery so that they can be mounted during the last machine shut down before the start of the experimental run. Omicron EMF3 e-beam evaporator and custom made evaporator can be provided only in special cases and WE DO NOT ACCEPT RESPONSABILITY FOR FAILURE OF THE EVAPORATORS. In case it is not possible to install the user's evaporator, the user has anyway to provide the materials needed for the evaporation and the boat or basket, well in advance before the experiment.



  • SCIENTA R3000 


    http://www.elettra.trieste.it/lightsources/elettra/elettra-beamlines/bach/scienta3000.html

    ENERGY RANGES


     

    More information will be soon available

    OLD: The VSW CLASS 150 hemispherical electron analyser (NOT AVAILABLE ANY MORE!)


    The pass energy can be changed continously from 5 eV to 85 eV.

    The acceptance angle depends on several factors: retard ratio, slit size at the focal plane,  The angular acceptance decreases with increasing retard ratio and also using a small slit or aperture will reduce the angular acceptance
    In practice if you are looking at say 500eV electrons with pass energy of 50eV (retard ratio of 10) the angular acceptance is around +/- 4 deg in the dispersive direction. If the pass energy is 10eV (retard ratio of 50) the angular resolution is around +/-2 deg.  There are two operation modes which shold be changed manually on the electronic modules:


    High Kinetic Energy HE (default) 30-1600
    Low Kinetic Energy LE (be very careful for KE<50eV) 0-100



    The fluorescence Grating Spectrometer ComiXS

    The fluorescence spectrometer ComIXS (Compact Inelastic X-ray Spectrometer) is an instrument devoted to the energy analysis of the photons emitted from the sample in the experimental chamber (under synchrotron radiation). It takes advantage of two variable line spacing spherical gratings to cover the range from 20 eV to 1200 eV with medium resolution and high efficiency. The data acquisition is made by a back-illuminated CCD camera optimized on the soft x-ray energy range. (More details on ComIXS)

    IMPORTANT!!!: Please contact beamline scientist for details on the current status/resolution of the spectrometer.


    The geometry of the fluorescence (and photoemission) measurements is summarized by the drawing.
    The x-ray emission angle is 60° from the incident monochromatized beam. The CCD position can be moved to select the proper energy window. A gate valve separates the main chamber from the spectrometer.
    On the same main chamber, the VSW CLASS 150 hemispherical electron analyser is mounted (not shown in the drawing) at -60° from the incident monochromatized beam.

     




    Off-Line Instruments and Tools

    Tool/Instrument Specifications Location
    Hot Plate 50° C-500° C
    Max Load 5 kg.
    Max dim. 200x200 mm.
    On the table between BACH acquisition room and LASER hutch
    Ultrasonic Cleaning Machine   On the table between BACH acquisition room and LASER hutch
    Electrical conductive UHV compatible silver epoxy Epo-Tek H21D (old) or H20E (new) BACH acquisition room
    UHV compatible Carbon tape; Several sample Clamps   BACH acquisition room
    Hot gun    
    N2 gas line   close to the LASER hutch
    Water cooling circuits   close to the LASER hutch
    Electric Drill   Black box in the cabinet between BACH acquisition room and LASER hutch
    Diamond Files, Sample preparation tools   BACH acquisition room
    Pyrometer (reads above 300° C )   Main Chamber area
    UHV Thickness monitor Sycon Instruments STM-100/MF (it can be mounted on the preparation chamber)
    High vacuum sample storage box   T-REX area
    Electromagnet (OFFLINE!) up to ~2 Tesla Between BACH acquisition room and LASER hutch
    Sample holders

    1 standard VG XL25VH

    2 standard VG XL25HC

    2 home-made sample carriers for heating by filament (for radiative sample heating up to 300° C or electron bombardment)


    2 home-made sample carriers for heating by direct current up to 10 A (e.g. Si, Ge, SiC)

    BACH acquisition room

     


    Endstation B

    This endstation is located at the end of the branch A where the spot dimensions on the sample are about 350x40 micron2. The experimental setup of the BRANCH B hosts a new endstation dedicated to x-ray magnetic circular dichroism in high magnetic fields (± 6.5 Tesla) along the beam and variable tempertaure from 1.9 K to 340 K on the sample in a base pressure of 4x10-11 mbar.  A surface preparation chamber will be connected for the investigations of the magnetic propertis of in situ grown samples. The endstation can be also used for pump-probe time-resolved XAS/XMCD spectroscopy experiments.


    This endstation has been assembled and installed at the end of 2011/beginning 2012. The first phase of the installation (superconducting magnet installation, magnet canister welding, T probes and current leads connections, electrical checking, and He leak check of the magnet canister and tank) has been performed with success in December 2012. The second part of the installation has been performed in January 2012. In March 2012 we have performed the on-acceptance tests with success!! We have reached the min T (1.8 K) and max T (340 K) on the sample and ±6.5 Tesla with a ramp rate of 1T/min with no quenches in a base pressure of 3.9x10-11 mbar (only by cryopumping). In March 2013 we have performed the first XMCD experiments and the endstation is now open to users.

    Endstation A+T-Rex Laboraory= Time-resolved pump-probe XAS

    The time resolved XAS/XMCD setup is operating at the Branch A of the BACH Beamline. The experimental setup combines Laser and Synchrotron Radiation (SR) in order to study the dynamics of the photo-induced excited states of electronic and magnetic systems. 

    The X-ray absorption spectroscopy (XAS and XMCD) open up various opportunities to probe laser-induced changes of the electronic, magnetic and geometric structure. The properties of the TR-XAS/XMCD@BACH endstation offer wide experimental conditions with respect to repetition rate, overall energy range, time-resolution, operation modes of the Synchrotron source and sample experimental enviroments.
       

    Elettra Synchrotron radiation source provide radiation pulse widths sufficiently short to investigate dynamic processes in the time between 60 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. For the optical excitation of the sample we use a regenerative amplifier system (RegA9000 from Coherent) providing 5µJ photon pulses at a repetition rate of 250 kHz or a Mira HP Ti:Sa oscillator with a pulsepicker and produces 25nJ pulses with a repetition rate tunable between 1 and 83.3 MHz. The XAS experiments are performed measuring the X-ray fluorescence yield by means of an ultra-fast MCP detector (Hamamatsu). Different acquisition modes are available: full XAS energy scan, fixed Energy-time delayed acquisitions.
     

     
    Feature of the Laser Sources RegA9000 Mira HP Ti:Sa oscillator
    Wavelenght 800nm; SHG: 400nm 800nm; SHG: 400nm
    Pulse width 100 fs 100 fs
    Pulse energy 5 μJ/pulse 25 nJ/pulse
    Repetition rate 200-250 KHz 83.3 MHz

    The experimental area around the branch C is flexible. User groups that wish to bring their own instruments or endstations to the beamline are encouraged to do so.
    We invite users interested in installing  a bulky piece of equipment (such as an entire experimental station) which takes a long time to assemble and dismount to discuss their project with the beamline local contacts well in advance before the submission deadline in order to check the technical feasibility.
    Elettra accepts a limited number of long term projects. These are allocations of beam time over a two-year period. The proposer has to explicitly declare that the instrumentation will be at Elettra for the whole time of the long term project and available to other users. For more info, please visit the user info section.

    Last Updated on Thursday, 07 March 2019 19:23