FOCUS GmbH: Recent Achievements on HAXPES Instrumentation · HAXPES 2009, May 20th to 22nd, Brookhaven National Laboratory, Long Island, NY FOCUS GmbH: Recent Achievements on HAXPES

HAXPES 2009, May 20th to 22nd, Brookhaven National Laboratory, Long Island, NY

FOCUS GmbH: FOCUS GmbH: Recent Achievements on Recent Achievements on

HAXPES InstrumentationHAXPES InstrumentationM.Merkel1*, M.Escher1, N.Weber1, J.R.Rubio‐Zuazo2, G.R.Castro2

1FOCUS GmbH, Huenstetten, Germany

2SpLine, Spanish CRG Beamline at the ESRF, Grenoble, France

m.merkel@focus‐gmbh.com

HAXPES 2009, May 20th

to 22nd, Brookhaven National Laboratory, Long Island, NY


Talk layoutTalk layout

•

FOCUS: Profile

•

Cylindrical Sector Analyser (CSA): Electron optical layout

•

Some examples with the single channel detector

•

Event counting 2D detector up to 15 keV:

design and implementation

•

Single shots, Survey spectra, Linearity, Resolution

•

Conclusions


FOCUS FOCUS GmbHFOCUS GmbH• German company

• Established in 1990• Premises in Hünstetten, Hessen (instruments)

and Leipzig, Sachsen (electronics & software)• 30 employees in total

• All FOCUS products are designed and manufactured in house

•Sales cooperation with OMICRON nanotechnology GmbH since 1991


UHV eUHV e‐‐beam Evaporation (0.1 to 1.2 kW): beam Evaporation (0.1 to 1.2 kW): The The popularpopular

EFMEFM

familyfamily

Sold more than 1200 pieces!

Sold more than Sold more than 1200 pieces!1200 pieces!


New Topic: Desktop New Topic: Desktop EE‐‐beam Welding beam Welding (2kW, 60kV) for Fine(2kW, 60kV) for Fine‐‐

and Micromechanicsand Micromechanics


Hg UV sourceHg UV sourceHg UV source

VUV source HIS13VUV source HIS13VUV source HIS13

Exciting: Photon sourcesExciting: Photon sources (UV & VUV)(UV & VUV)


CSA 200 & CSA 300CSA 200 & CSA 300CSA 200 & CSA 300

Approved: Approved: Electron & Ion Spectroscopy Electron & Ion Spectroscopy (0..3200eV; UPS, XPS, AES, ISS)(0..3200eV; UPS, XPS, AES, ISS)


SHA 50SHA 50SHA 50

And: Angular Resolved Electron Spectroscopy And: Angular Resolved Electron Spectroscopy (0..1600eV; ARPES)(0..1600eV; ARPES)


HV CSAHV CSAHV CSA

Hot topic: High Energy Electron Spectroscopy Hot topic: High Energy Electron Spectroscopy (HAXPES, 1..15000 eV)(HAXPES, 1..15000 eV)


SPLEEDSPLEEDSPLEED

More and more: More and more: Spin Analysis Spin Analysis


IS‐PEEMISIS‐‐PEEMPEEM

Images: Photo Electron Emission MicroscopyImages: Photo Electron Emission Microscopy (PEEM)(PEEM)


High end: Energy Filtered XPEEM High end: Energy Filtered XPEEM & k& k‐‐Space Imaging:Space Imaging:

NanoESCANanoESCA™™

& Momentum Microscope& Momentum Microscope

HAXPES 2009, May 20th to 22nd, Brookhaven National Laboratory, Long Island, NY ©MS 2009

Momentum Microscope: Angular resolved UPSMomentum Microscope: Angular resolved UPS

Single shot image of the Cu(111) Fermi Surface

Acquisition time 60sec

He I excitation, hν

= 21.2 eV

VUV source HIS 13

With a standard ARUPS set-up it will take many hours

Large angles are very difficult to image

K||x

K||yCu(111)


1 2

3 4

5 6

Extracted k-space distribution to corresponding peaks in UPS spectrum

Fitted peak areas (Phi Multipak)

6 peak positions in spectrum treated with background subtraction

Momentum Microscope: Angular resolved UPSMomentum Microscope: Angular resolved UPS


CCylindrical ylindrical SSector ector AAnalysernalyser (CSA)(CSA)

detector in field detector in field

free regionfree region

Risley J.S, Rev. Sci. Instrum. 43 (1971) 95; Sar-El H.Z, Rev. Sci. Instrum. 38 (1967) 1210; Sar-El H.Z, Rev. Sci. Instrum. 41 (1970) 561.J.R.Rubio-Zuazo, M.Escher, M.Merkel and G.R.Castro, J. of Phys. Conf. Ser. 100 (2008)


Energy resolution (base resolution)

HSA

CSA (45°)23

max

21

2arcsin69.0

2)(48.5

13.4

ipass Rxrad

rww

EE

221

2)(

2

radr

wwE

Emeanpass

• 2 x better energy resolution at comparable physical size•

larger angular aperture possible (2nd order focussing)

Transmission• HSA: angular term produces asymmetrical peak shape

Pro CSA

Contra CSA• additional off axis term (non‐dispersive direction)• not common

Comparison: CSA (cylindrical sector) vComparison: CSA (cylindrical sector) vs. HSA (hemispherical)s. HSA (hemispherical)


Comparison: CSA (cylindrical sector) vComparison: CSA (cylindrical sector) vs. HSA (hemispherical)s. HSA (hemispherical)

ResolutionResolution

TransmissionTransmission

FocussingFocussing

Detection, SpinDetection, Spin

HSA

2 x higher at same size

CSA

2nd order focussing

off‐axis term limits

non‐dispersive Trans.

1st order focussing

non dispersive Trans‐

mission not restricted

Astigmatic,

no point to point

imaging

Stigmatic, good for

imaging and k‐space

90°

deflection spin detection

detector in field free region

good integration into experiment

180°

deflection,

detector on site of exit slit,

fringe field!


HVHV‐‐CSA: Technical featuresCSA: Technical features•

High Voltage Cylinder Sector Analyser

•

300mm slit to slit distance

•

Isolation up to 20keV

•

Operated up to 15 keV routinely

•

Entrance lens:

•

Retardation ratio up to 1500

•

large working distance (50mm)

•

small lens diameter

•

Very compact (and slim in two

dimensions) compared to

HSA with same dispersion

•

High angular acceptance

due to second order focusing

•

Dispersion plane in field free region

•

90°

deflection ideally suited

for

spin‐resolved studies (upgrade option)


HV CSA (single channel) at , ESRF HV CSA (single channel) at , ESRF


Spectroscopy at both very lowSpectroscopy at both very low……

Ag‐valence band:

Spectroscopy at low KE

Spectrometer

Energy Resolution

dE ~ 40meVspectrometer

cutoff

Fermi

cutoff


……and very high electron energies with the and very high electron energies with the samesame

analyser (and same electronics!)analyser (and same electronics!)

3600 3400 3200 3000 2800 2600 2400 2200

0,0

0,5

1,0

1,5

2,0

2,5

3,0

x3

3p3/2 3d

5/2

3p1/2

3d3/2

3sh = 9KeV

h = 17KeV

EP= 200eV

w1=w

2=9mmAu

(b)

Inte

nsity

(Kcp

s)

Binding Energy (eV)


140 120 100 80 60 40 20 0 -20

h=13KeV x8

Au (21 nm)/Cu (Polycrystalline)

h=15KeV

h=11KeV

h=9KeV

h=7.5KeV

Cu 3d

Au 5dAu 5p3/2

Au 5p1/2

Cu 3p1/2,3/2

Au 4f5/2, 7/2

Au 5SCu 3S

x14.25

x3.5

x1.3

Inte

nsity

(arb

. uni

ts)

Binding energy (eV)

0 5 10 150.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60 Fit to simple model Int Cu 3S / Int Au 5S

Int (

Cu3

S)/ I

nt (A

u 5S

)Photon Energy (KeV)

Application on to Au/Cu system (single channel detector!) Application on to Au/Cu system (single channel detector!)


General: Counting Detector (vs. Analog)

•

Counting statistics = Poisson statistics•

Reproducible behaviour in terms of its linearity given by the dead time•

Linear response down to very low count rates•

Comparable to standard spectra taken with 1D channeltron detectors

2D: Fast Optical Transformation (vs. Multi Anode, DLD etc.)

•

Counting chain is related to ground•

Risk of high voltage sparks on counting electronics is completely eliminated•

Simple potential separation with optical interface

(ScintllatorLensCamera)

•

By means of 2‐dimensional optical encoding the set up of the channel width

(and shape), remains flexible

•

Application of high flux pulsed sources (FEL, Laser excited plasma sources,

etc.) becomes feasible

Improving of the efficiency: 2D detectorImproving of the efficiency: 2D detector


Implementation of the novel 2DImplementation of the novel 2D‐‐detectiondetection

HV‐CSA (15keV)HV‐CSA (15keV)

Entrance zoom lensEntrance zoom lens

Camera based

2D event counting

detector

Camera based

2D event counting

detector



Event counting: Analog raw imageEvent counting: Analog raw image


Event counting: Detected eventsEvent counting: Detected events


2D event counting: 2D event counting: Comparison of analog and counted images(PEEM)Comparison of analog and counted images(PEEM)

Analog (PEEM)Analog (PEEM)Counted (PEEM)Counted (PEEM)


2D detection: Running a single shot experiment2D detection: Running a single shot experiment


Raw-data extracted with 320 channels from the event image; peak width of elastic peak about 1.2eV fwhm.

Example of an elastic peak Example of an elastic peak with fixed analyser voltageswith fixed analyser voltages

•Settings:•25 sec measuring time•320 channels (approx. 0.1eV / channel)•Pass energy 320eV•Entrance slit 1mm diameter•Usable detector width approx. 9% Epass (here 28eV)


14,490 14,495 14,500 14,505 14,5100

1000

2000

3000

4000

5000

6000

7000

Snapshot-Spectrum elastic peak of electron gun

140 energy channelsdE=0.2eVEp=320V0.5mm slit

Inte

nsity

[cts

]

kin. Energy [keV]Single shot (snapshot) spectrum• High kinetic energy• Many channels are possible (useful are 200 to 300)

2D event counting: Single shot at 14.5 keV2D event counting: Single shot at 14.5 keV


Accumulation of wide spectra: Accumulation of wide spectra: Some kind of patch workSome kind of patch work

Survey spectrum of Ag on W

(MgKα

1281eV; 200 eV pass energy)

Ag3d

(100eV pass energy)


8880 8900 8920 8940 8960 8980 9000 9020 9040 90600

200

400

600

800

1000

12005s

5f

5d

5p3/25p1/2

co

unts

Ekin (eV)

h = 9keV Epass 100

Au Valence Band at Au Valence Band at 100 eV Pass Energy100 eV Pass Energy


8880 8900 8920 8940 8960 8980 9000 9020 9040 9060

0

1000

2000

3000

4000

5000

5d

5p3/2

5p1/2

5f5s

co

unts

Ekin (eV)

h = 9keV Epass 200

Au Valence Band at Au Valence Band at 200 eV Pass Energy200 eV Pass Energy


860 870 880 890 900 9100

50

100

150

200

250

300

350

Ag3dMgK

8W 34W

Inte

nsity

[kcp

s]

Kinetic Energy [eV]

nrm

nrnmrm

111 m(r): spectrum with the lower count rate

m(rn): spectrum with the higher count rate

n: ratio fit

τ: dead time (equivalent to the dead time

of a 1D-detector)

0 50 100 150 200 250 300 3503,8

4,0

4,2

4,4

=235ns1/n = 4.3

measured data linear fit

Inte

nsity

Rat

io

Intensity [kcps]

Exposition time: 2msec

2D event counting: Verification of linearity and dead time2D event counting: Verification of linearity and dead time

M.P. Seah et al. J. Electron Spectrosc. Relat. Phenom. 104 (1999) 73-89Manella et al. J. Electron Spectrosc. Relat. Phenom. 141 (2004) 45-59


Future perspectives:Future perspectives:

Spin?

Yes! But: Count rates!(?)

Ambient pressure?

Yes! But: High voltages!(?)


SummarySummary

HAXPES Analyser• CSA concept vs. HSA (for high energy applications)

• Compact, slim, high transmission at high kinetic energies

• HV CSA electronics & software

• Recent Results

• 2D detection by means of fast event mapping (counting)

FOCUS GmbH• Company

• UHV deposition

• e‐beam welding

• Light sources

• Spectroscopy: UPS, XPS, AES, ARPES, ISS, HAXPES

• PEEM & NanoESCA


AcknowledgementsAcknowledgements

•BM25/SpLine staff

• FOCUS GmbH

• ICMM‐CSIC

• ESRF

•Financial supported by

the Spanish MCYT under the project No.FPA2001‐2166

and the German BMBF under project FKZ:13N9033

(„“CORA“)

http://www.bmbf.de/

FOCUS GmbH: Recent Achievements on HAXPES Instrumentation · HAXPES 2009, May 20th to 22nd, Brookhaven National Laboratory, Long Island, NY FOCUS GmbH: Recent Achievements on HAXPES

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