Manual_VGScientaR3000

VG SCIENTA R3000

GEOMETRY

β: assymetry parameter from atomic calculation of photoionization; for s orbitals β=2; for p, d, f orbitals see https://vuo.elettra.eu/services/elements/WebElements.html

CORRECTION FACTOR TO THE ANGULAR SCALE IN A21 MODE

In the case of ARPES data acquisition in A21 mode, a correction has to be applied to the angular scale. The correction is a simple multiplication factor of 1.2.

NON LINEARITY

Be aware that Scienta3000 has not a linear response. The spectra should be corrected according to the procedure described here (only for data acquired in SWEPT MODE).

TRANSMISSION CALIBRATION

Transmission function calibration of an angular resolved analyzer for X-ray photoemission spectroscopy: Theory vs experiment
Drera G, Salvinelli G, Ã…hlund J, Karlsson PG, Wannberg B, Magnano E, Nappini S, Sangaletti L
Journal of Electron Spectroscopy and Related Phenomena, Vol. 195, pp. 109-116 (2014)
doi: 10.1016/j.elspec.2014.06.010

DATA ACQUISITION

A)DETECTOR SETUP: Setup-->Global Detector (1 slice for XPS, 488 slices for ARPES). Set the straight slit correction ON or OFF depending if you are using a straight or curved slit.

B)FILE->OPTIONS...SES Options->Acquisition->Enable or Disable Use Multiple Sequences.

C)RUN->SETUP. In the region Editor choose the Folder where the files will be saved (after creating it inside the folder D: Users). The files can be saved as Igor ibw (reccomended) and/or txt (more memore required).

XPS ACQUISITION

1. Close BL valve first
2. Turn on the power supply (outside, VG Scienta rack)
3. Run the SES program. (if camera does not show up, right click the mouse and select the Run as Administrator mode  the SES program)
4A. Close BL valve. MENU: Calibration-->Voltages (with BL closed!). Select Pass Energy and Kinetic energy in order to see a core level peak or the secondary electrons (100 eV).
CAREFUL: At the beginning choose a low PE in order not to have too many counts.
In order to see the counts select View AREA
The counts have always to be lower that 1.500.000/ second (the risk is damaging the MCP permanently!). If there are too many counts, close the BL slits or decrease the PE
4. B Open BL valve
5. Optimize the position of the sample (y is very sensitive and depends also on the PE selected. So, y has to be optimized for each PE)
6. MENU: Run-->Setup: Create a new region: Name, PE, the KE range, the Transmission or angular mode, the number of iterations, the frame rate...at the end read the hv energy. If you are acquiring ARPES activate the detector setup. In the detector setup remember to set the straight slit correction ON or OFF depending if you are using a straight or curved slit and the region/number of slices. As a rule of thumb one should have at least 5 steps per total resolution point, i.e. step size=DeltaE/5.

Detailed Information on how to set up the Energy regions in a Sequence and other useful information for new users from the VGScienta Technical Notes: click to download the VGScienta file PRE-SET Region Guide.

DETECTOR SETUP

Setup-->Global Detector.
FOR ANGLE INTEGRATED XPS: Define 1 single Slice. Define the vertical area inside the detector in order to cut away the high-noise top and bottom edges of the CCD
FOR ARPES/PED: Define 488 slices. Full area of the detector.

XPS QUICK ACQUISITION MODE (320msec/spectrum)

1. Menu-->Installation-->Instrument-->AV Delay=0 (insted of 0.5); Region Delay=0 (instead of 1)
2. Run--->Setup-->Select:
(a) A21 (if the numb of counts is high, instead of Transmission, in order not to burn the central part of the CCD)
(b) Fixed Mode
(c) Add Dimension
(d) Number of Frames=1 (320 msec/spectrum) or more if more statistics is needed.
Other typical acquisition times are, e.g. are frames=5 (410 msec/spectrum); frames=10 corresponds to 480msec/spectrum
3. Setup-->detector: select 1 slice instead of 488. This will make the data file "lighter"

RESTART VG SCIENTA R3000 PC:

(a) (CNTRL+ALT+TAB--->kill SES process). Be aware that Voltages remain ON if you stop SES using this abrupt procedure.
(b) Before running SES, follow the procedure to recover data not saved.
(c) start SES
(b) Execute the Monochromator set up procedure (select proper grating and undulator on for NEXAFS or off for XPS)

PLOTTING DATA USING VG SCIENTAR3000 IGOR MACRO

1. Click on the name of file.bin
2. VGScienta/SpectrumInfo/Namefile (optional)
3.VGScienta/ReduceDimension/Namefile---integrate over y--Namefile_sect (default)
4.VGScienta/ReduceDimension/Namefile_sect---integrate--Namefile_sect_sect (default)

For PEY NEXAFS: Load counter and Io files, then use the Igor macro (PBACH7-IgorPro) to calculate irel.

MONOCHROMATOR SET UP

1. Monochromator-->Setup-->(a) Browse R3000MonoOnlyMYDLL.dll
(b) Setup-->setup.
(b1) SETUP ACTION: Select grating (eg SG3), Local, check that Description is SG3 (or the grating selected), method HTTP. SAVE and then READ.
Check that Name and IP are "localhost"
QUIT, OK
(b2) SETUP SETTINGS. Check that Path is D:\SES 1.2.6-r7_6MS044_new\dll\BeamlineSettings\Monochromator

2. Check again that the grating selected is read correctly!
Monochromator/Manual Control--> GET
Check that the hv is the same read by the Main Panel

MONOCHROMATOR and UNDULATOR SET UP

If you want to move both Monochromator and Undulator then load R3000MonoAndUndDLLv2.dll instead of R3000MonoOnlyMYDLL.dll. The setup instruction is inside the plug-in window.

WORK FUNCTION

LOW ENERGY MODE: PE=5, 10, Transmission Mode: WF=4.50 eV, before 2020
LOW ENERGY MODE: PE=5, 20, Transmission Mode: WF=4.61 eV for data from year 2020
HIGH PASS ENERGY MODE: PE=20, 50: WF=4.64 eV; PE 100 eV: WF = 4.78 eV for data before year 2018
HIGH PASS ENERGY MODE: PE 50eV: WF=4.70 eV; PE 100eV: WF = 4.86 eV for data from year 2018

For the measurement of the WORK FUNCTION IN A MATERIAL please follow the instructions (in particular the settings) here.

XPS RESOLUTION

For HPE the resolution is almost linear with the slit and the number of counts.
An approximate estimation of the resolution is given by the following formula: resolution=PExSlitWidth/(2x135) (analyser mean radius is 135mm).
For BACH SCIENTA3000 the following resolutions have been measured:

Slit	Analyser resolution (meV) PE=10 eV	Counts
0.2c	9.1	27500
0.4c	13.8	61000
0.8c	26	132000

Slit	Analyser resolution (meV) PE=20 eV	Counts
0.2c	16	15000
0.4c	27	27000
0.8c	50	48000

PART I: Keithley 628 amplifier connection

1. Connect a BNC cable from the mirror Io (and eventually sample Is) to the INPUT channel (without the yellow impedence).
2. Check that the OUTPUT channel is connected to the white external card (usually to the channels A0 and A1 of the card) which is connected to the VG Scienta R3000 PC by a USB.
It is possible to connect to the output voltage also a tester using a "T" BCN to read the signal in real time or to connect the output signal to the National Instrument card inside the hutch (this allows measuring Io and Is also with the Labview VIs). .
2. Close the FE
3. Switch on the amplifier. Make sure zero check is off. Select a range typically 10+10 or 10+9 or 10+8 V/A for Io in order to have the signal between -10 and +10V. If e.g. the current is 10-10 use 10+9.
4. Press SHIFT+ZERO check correct. The tester shoud now read 0.0
5. In setup menu select RISE FILTER TIME: 300 msec (using the knob)
6. In the enable menu select FILTER (led on)

NOTE: The best connection is through HTTP. In the DLL: MonoBACH, be sure that Method"1" is selected (defined twice inside the file). For TCP connection Method is "0", but it is causing frequent bugs in the monochromator communication protocols (Mono has to be rebooted frequently).
If there are problems to move monochromator from SES program, change DLL from the present version (HTTP -->TCP or TCP -->HTTP).
If also the undulator does not move insert the password toccata moving the gap from Internet explorer.

PART II. SOFTWARE SETUP

NEW (DEFINE CFS inside Region Editor)
Use SES NEXAFS software (icon in the desktop)
Monochromator set up (Undulator enabled)
Setup-->signalssetup (device 1, channels 0 e 1 for Io and Is, respectively). In Calibration voltage check that it is reading Io.
RUN->SETUP. Create a New Sequence dedicated ONLY to XAS measurements (Run-->setup-->File-->NewSequence)
RUN->SETUP. In the region Editor: select CFS. edit (select the energy range and step);
Edit XPS region (name,PE,KE, step,frames) region: (standard) select:
FIXED mode, A21
Acquisition time 1-7 seconds per point
Acquisition mode: FIXED
Detector select-->Active Detectors: select Camera & Signals
Possible settings for PE and KE for secondary electron yield:
PE=20--->KE=11 (highest count rate: 328000)
PE=50-->KE=27 (140000)
PE=100-->KE=55 (132000)
PE=200-->KE=115 (260000)
You can copy this Region and define e second energy range and step in order to make an acquisition with different photon energy steps along the NEXAFS.

ARPES at LOW ENERGY

Typical settings at 47 eV: Low Pass mode, Pass energy 10eV, A21 mode, VB region ca. 14 eV from Fermi edge, step size 25 meV, step time: da 57 ms-200ms Slits: straight (depends on the counts).

RESONANT PHOTOEMISSION

Use SES 1.3.1-r5 NEXAFS software (icon in the desktop). Note the other version frozens afetr 5 steps (error 510)
Monochromator set up (Undulator enabled)
Setup-->signalssetup (device 1, channels 0 e 1 for Io and Is, respectively). In Calibration voltage check that it is reading Io.
RUN->SETUP. Create a New Sequence dedicated ONLY to RESPES measurements (Run-->setup-->File-->NewSequence)
Use CIS in the Region editor and define the energy range and step.
In the region editor, define the BINDING energy range and pass energy.

NEXAFS

OLD METHOD (MULTIPLE SEQUENCES)
A)DETECTOR SETUP: Setup-->Global Detector.
B)FILE->OPTIONS...SES Options->Acquisition->Enable or Disable Use Multiple Sequences.
c)RUN->SETUP. In the sequence Editor choose the Folder where the files will be saved (after creating it inside the folder D: Users). The files can be saved as Igor ibw (reccomended) and/or txt (more memore required).
a.Main panel: enable Io and Is.
b.Desktop: Measurement and Automation-->Data Neighborhood--> NI DAQ-->Read Io and Is.
Check that Io and Is are read correctly.
1. Monochromator set up (Undulator enabled)
2. Install-->Instrum-->External (Io_NIDAQ.dll) (default)
3. Setup-->signalssetup (device 1, channels 0 e 1 for Io and Is, respectively). In Calibration voltage check that it is reading Io.
4. Run-->setup
Create a New Sequence dedicated ONLY to XAS measurements (Run-->setup-->File-->NewSequence)
a) In the Sequence Editor: select CFS.
b) In the Sequence Editor: CFS edit (select the energy range and step); select Intensity vs Photon energy
c) In the Region Editor: Edit XPS region (name,PE,KE, step,frames) region: (standard) select:
FIXED mode, A21
Acquisition mode: FIXED
Detector select-->Active Detectors: select Camera & Signals
NOTE: After using CFS (NEXAFS), going back to Normal in the sequence editor the number of iterations remains equal the number of energy steps (while it should be 1). So make sure to set it again to 1, if you want to acquire the normal XPS spectra again.

DATA SAVE LOSS AND RECOVERY OPTIONS

(from VGScienta Technical Notes (Courtesy of VGScienta): download the VGScienta pdf file Data Save and Loss Recovery options)

The SES software records data that is stored in a
temporary file during acquisition. In the event of a software or computer crash during a spectrum
recording the data can be lost. In this application
note a list of tips and tricks will be listed in order
to minimize data loss and maximize data recovery.
Data acquisition possibilities: In the SES- software it is
possible to record a spectrum that consists of several
iterations of the studied region. The number of iterations
can be chosen to a fix nr or the Repeat until stopped option
can be used. These options can be accessed both in
the region editor and in the sequence editor. The resulting number of iterations is the same
in either of the two, but there is a difference in when the
data is stored during the recording.
An example: The goal is to record a spectrum using 10
iterations, which is saved as a .pxt file. Region editor) If
the number of iterations is set to 10 in the region editor
(and 1 in the sequence editor) and the recording is started
the data will be acquired in a temp file that is converted
to a .pxt file after the 10 iterations are done. Sequence
editor) If the number of iterations is set to 10 in the sequence
editor (and 1 in the region editor) a .pxt file will
be stored after each iteration. When the next iteration is
started the previous .pxt file will be overwritten and after
10 iterations a single .pxt file is stored that is containing
one spectrum, which is equal to the one recorded using
the region editor iteration.

For long recording times it is recommended to use the
sequence editor for iteration, since the data loss in case
of a crash is only one iteration, compared to all iterations
if the region editor is used. It is however possible to retrieve
temporary data using the SES-program (version nr
1.2.6 and beyond).

Data recovery

(Courtesy of VGScienta):

Data recorded by the SES-program is
stored in a temporary file before .pxt conversion. For
development documentation concerning the file format
see: ftp://ftp.gammadata.se/Scienta/SES/docs/developer/
workingfiles.txt. The temp file is stored in the work directory
(folder), which is a subdirectory of the SES folder.
If a crash occurs data might still be located in the work
folder. In order to retrieve the data:
1) Crash.
2) Make a copy of the work folder before starting
the SES-program (as starting the program will
empty the work folder).
3) Start the SES-program.
4) Go to File → Open spectrum…
5) Choose Files of type: Recover spectrum (*.info).
6) Open the spectrum your_file_name.nfo. The
recovered data is displayed.
7) Save the spectrum using the File → Save Spec
trum as… dialog. In this dialog it is possible to
choose data file format.
For more information contact service@vgscienta.com

HIGH AND LOW Pass Energy SETTINGS

How to change between high and low pass energy (ONLY IF authorized by BL staff!!): download the VGScienta Technical Note (Courtesy of VGScienta) High and Low Pass Settings.

1. Turn the high voltage off at the HV-rack
2. Change the junction box cable positions to the desired pass energy mode (see the VGScienta Technical Note).
3. Enter the Calibration-Voltages menu, set Pass Energy 20eV (which is fine for both high and low pass modes) and an appropriate kinetic energy (e.g. 100 eV). Then press OK button.
4. Enter the setup and choose high or low pass mode. A dialog box will appear. Press OK button.
5. Exit SES software (This step will prevent loss of correct pass energy mode in case of software crush).
6. Run SES software and make sure the correct pass energy mode is set.
7. Turn the high voltage on at the HV-rack.

KINETIC ENERGY RANGES

NOTE: do not use PE=5 and 10 with High Pass Energy.

SPECTROMETER STARTUP AFTER a BAKE OUT

VENTING: Before venting select the large aperture hole.
Quick Procedure: How to start up the VG Scienta 3000 after a bake out (ONLY IF authorized by BL staff!!):
With the Hardware power supply OFF, In Voltage Calibration Select MCP and set it to zero. Select Screen and set it to ZERO.
Then switch the power supply on and in steps of 100V set MCP to 1500 V and screen to 3600 V.

Detailed Instructions: How to start up the VG Scienta 3000 after a bake out (ONLY IF authorized by BL staff!!): download the VGScienta Technica Note (Courtesy of VGScienta) SPECTROMETER START-UP

PRESSURE INTERLOCK

5x10-8 mbar

Ultima modifica il Lunedì, 15 Novembre 2021 19:47