Peter Puschnig, APS March Meeting, Boston 2012

Motivation

Orbital tomography:Deconvoluting photoemission spectra of organic molecules

Austria Austria Germany Austrian Science FundP23190-N16

ARPES of PTCDA / Ag(110)ARPES of PTCDA / Ag(110)

Peter Puschnig, APS March Meeting, Boston 2012

Glöckler et al,Surf. Sci. 405, 1-20 (1998).STM

Slide 1

Identifying OrbitalsIdentifying Orbitals

Slide 2Peter Puschnig, APS March Meeting, Boston 2012

Identifying OrbitalsIdentifying Orbitals

Self-interactioncorrected functional

Peter Puschnig, APS March Meeting, Boston 2012 Slide 3

ARPES of PTCDA / Ag(110)ARPES of PTCDA / Ag(110)

Peter Puschnig, APS March Meeting, Boston 2012

Glöckler et al,Surf. Sci. 405, 1-20 (1998).STM

Slide 1

Photoemission IntensityPhotoemission Intensity

One Step Model

Peter Puschnig, APS March Meeting, Boston 2012 Slide 4

Photoemission IntensityPhotoemission Intensity

molecular orbital

One Step Model

Peter Puschnig, APS March Meeting, Boston 2012 Slide 4

Photoemission IntensityPhotoemission Intensity

[Feibelman and Eastman, Phys. Rev. B 10, 4932 (1974).]

Approximation: final state = plane wave

Fourier Transform of Initial State Orbital

plane wave ei k r

One Step Model

molecular orbital

Peter Puschnig, APS March Meeting, Boston 2012 Slide 4

Comparison with DFTComparison with DFT

Molecular Orbitalin Real Space

Calculation ofthe Fourier Transform kx (1/Å)

Hemispherical Cut Through3D Fourier Transform

x

kx (1/Å)

k y (

1/Å

)

kz (1/Å

)

y

z

Peter Puschnig, APS March Meeting, Boston 2012

ky (1/Å

)

Slide 5

Peter Puschnig, APS March Meeting, Boston 2012 Slide 6

The Toroidal Electron Spectrometer for Angle-Resolved Photoelectron Spectroscopy with Synchrotron Radiation at BESSY II

Toroidal Electron Energy AnalyzerToroidal Electron Energy Analyzer

HOMO and Filled LUMOHOMO and Filled LUMO

Puschnig et al. PRB 84, 235427 (2011), Ziroff et al., PRL 104, 233004 (2010).

Peter Puschnig, APS March Meeting, Boston 2012

M1=FLUMO

M2=HOMO

Slide 6

What is the nature of M3?What is the nature of M3?

M2=HOMO

M1=FLUMO

?

Peter Puschnig, APS March Meeting, Boston 2012 Slide 7

ARPES Data-CubeARPES Data-Cube

Peter Puschnig, APS March Meeting, Boston 2012 Slide 8

Eb

kx

ky

ππ -„bands“ of PTCDA-„bands“ of PTCDA

Peter Puschnig, APS March Meeting, Boston 2012 Slide 9

What is the Origin of M3?What is the Origin of M3?

Peter Puschnig, APS March Meeting, Boston 2012

E C F

Slide 10

What is the Origin of M3?What is the Origin of M3?

Peter Puschnig, APS March Meeting, Boston 2012

E C F

Puschnig et al. PRB 84, 235427 (2011), see also: Dauth et al., PRL 107, 193002 (2011).

Slide 11

Projected DOS from ARPES!Projected DOS from ARPES!

Peter Puschnig, APS March Meeting, Boston 2012

C

D

E

F

-3.8 -3.6 -3.4 -3.2 -3.0 -2.8

Eb (eV)

measuredphotemission

data cube

calculatedorbitals

Fit parameters= PDOS

Slide 12

Benchmark for TheoryBenchmark for Theory

Peter Puschnig, APS March Meeting, Boston 2012

C

D

E

F

Slide 13

[1-1

0]

Ag-

row

dire

ctio

n

ConclusionConclusion

Peter Puschnig, APS March Meeting, Boston 2012 Slide 14

Orbital Tomography● Make use of characteristic momentum space patterns● Unambiguous identification of molecular features● Density of states projected onto molecular orbitals● Deconvolution beyond limits of energy resolution

Other ApplicationsReal space reconstruction of molecular orbital densities

Puschnig et al., Science 326, 702 (2009).

Hybridization of molecular orbitals mit metallic states

Ziroff et al., Phys. Rev. Lett. 104, 233004 (2010).

Berkebile et al., Phys. Chem. Chem. Phys. 13, 3604 (2011).