Scanning tunneling microscopy (STM)

1
B Spectroelectrochemistry (ch. 17)
Scanning tunneling microscopy (STM) Atomic force
microscopy (AFM) Scanning electrochemical
microscopy (SECM) UV visible
spectroscopy Transmission experiments Specular
reflectance ellipsometry Internal reflection
spectroelectrochemistry Second harmonic
spectroscopy Vibrational spectroscopy IR
spectroscopy, Raman spectroscopy Electron ion
spectroscopy XPS, AES, LEED, HREELS, mass
spectroscopy Magnetic resonance methods ESR,
NMR Quartz crystal microbalance X-ray methods
XAS, XRD
2
Vibration spectroscopy Infrared
spectroscopy Infrared spectroelectrochemistry
(IR-SEC)
3
Cell for IR-SEC
4
EMIRS (electrochemically modulated infrared
reflectance spectrosocpy) Potential is modulated
between one where the species of interest is
absent one where it is electrochemically
generated
5
SNIFTIRS (subtractively normalized interfacial
Fourier transform IRS) or PDIRS (potential
difference IRS) or SPAIRS (single potential
alteration) Spectra obtained separately at two
potentials ? subtraction
6
IRRAS (IR reflection absorption spectroscopy) IR
absorption at fixed potential
7
SEIRA (surface enhanced IR absorption) IR to
study adsorbed species (reactants, intermediates,
products) ? orientation potential dependence of
the adsorbed species
SNIFTIRS
8
In-situ FT-IR spectroscopy

• Diffuse Reflectance Infrared Fourier Transform
  Spectroscopy (DRIFT)

• Attenuated Total Reflectance Spectroscopy (ATR)

Transmission measurement Reflection-Aborption
infrared Spectroscopy (RAS) Photoacoustic
Spectroscopy (PAS) Surface Electromagnetic Wave
spectroscopy (SEW)
9
In-situ FT-IR
In situ FT- IR cell
10

• In situ FT-IR

CO/Pt
11
Raman spectroscopy
12
Raman spectroscopy molecular vibrational
information complementing IR spec. Raman in
electrochemical system signal enhancement -
Resonance Raman spectroscopy (RRS) - Surface
enhanced Raman spec. (SERS) molecules adsorbed
on certain surfaces

(Ag or Au)
13
RRS of TCNQ electrochemically generated TCNQ-
14
Transients in Raman intensity
15
SERS for Os compound on Ag electrode as ftn of
potential
16
SER spectra for benzene on Pd
17
In-situ Raman Spectroscopy
18
In-situ Raman microscopy (??? ??? LiCoO2 ??? ??)
25oC
60oC
? LiCoO2 ? graphite ? acetylene black
Brodd (2003)
19
Electron and ion spectrometry Ultra high vacuum
(UHV)
Excitation
Detection X-ray photoelectron
spectroscopy (XPS) Photons(X-ray)
Electrons UV photoelectron spectroscopy (UPS)
Photons (UV) Electrons Auger electron
spectroscopy (AES) Electrons
Electrons Low-energy electron diffraction
(LEED) Electrons
Electrons High resolution e- E loss spec.
(HREELS) Electrons
Electrons Rutherford backscattering (RBS)
H or He H or
He Secondary ion mass spec. (SIMS)
Ions Ions Laser
desorption mass spec. (LDMS) Photons
Ions
20
Detection limits, sampling depth, spot size
(spatial resolution)
21
UHV-electrochemistry
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X-ray photoelectron spectroscopy (XPS, or ESCA)
23
Schematic diagram of XPS
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XPS for Pt 4f levels
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XPS for gassy carbon electrodes
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XPS for copper electrodeposition (a) Bulk Cu (b)
Cu UPD
27
Electrochemical X-ray Photoelectron Spectroscopy
Univ. of Illinois
28
Electrochemical XPS
Glove Box
UHV-XPS
Ex-situ Analysis without Contamination
29
Auger electron spectroscopy
30
Ni oxide on Au
31
AES Depth profiles for GaAs
32
AES depth profiles for MgPc
33
Electrochemical Auger Electron Spectroscopy
34
Low-energy electron diffraction
35
High resolution electron energy loss spectroscopy

• SCN- on Ag(111)
• -0.3 V
• 0.14 V

36
Mass spectrometry Differential electrochemical
mass spectrometry (DEMS)
37
DEMS fuel cell catalysts for methanol(solid)
formic acid(dotted) oxidation
38
Magnetic resonance methods Electron spin
resonance NMR
39
Electrochemical ESR
40
Quartz crystal microbalance
41
QCM PVF on Au
42
X-ray methods Synchrotron X-ray absorption
spectroscopy Absorption edge (energy that is
just needed to eject a particular core electron,
e.g., 1s e- (K edge), 2p3/2 e- (L3 edge) Fe Fe
oxides K-edge 7.112 keV Within 10-40 eV X-ray
absorption near-edge structure (XANES) (or
near-edge absorption fine structure (NEXAFS)) ?
oxidation state ligand envirionment About 50
keV extended X-ray absorption Fine structure
(EXAFS) ? distance arrangement of atoms
43
X-ray diffraction techniques
44
In-situ XRD
In-situ XRD patterns of LixFeSnO4 during
initial lithium intercalation and
deintercalation.