photoelectron spectroscopy of multiply-charged anions
DESCRIPTION
Photoelectron Spectroscopy of Multiply-Charged Anions. Lai-Sheng Wang Department of Physics, Washington State University & Chemical & Materials Sciences Division, Pacific Northwest National Laboratory. Ken: Congrat to your (60 ± 1)th B-Day!. Anion 2007 6/29 – 7/3, 2007 Park City, Utah. - PowerPoint PPT PresentationTRANSCRIPT
Washington State University
Pacific Northwest National Laboratory
Photoelectron Spectroscopyof Multiply-Charged Anions
Lai-Sheng WangDepartment of Physics, Washington State University &
Chemical & Materials Sciences Division, Pacific Northwest National Laboratory
Anion 20076/29 – 7/3, 2007 Park City, Utah
Ken: Congrat to your (60±1)th B-Day!
Washington State University
Pacific Northwest National Laboratory
Multiply-charged anions were rarely observed in the gas phase
e-M- M2-
e2
R
R (e- -- M-)
Formation of multiply charged anions by sequential electron attachments:
improbable
+
E
M2-
Washington State University
Pacific Northwest National Laboratory
J. Chem. Phys. 50, 1896 (1969)
The earliest observed doubly charged anion
Washington State University
Pacific Northwest National Laboratory
Phys. Rev. Lett. 67, 1242 (1991)
Doubly-charged carbon clusters and fullerenes
Cn2– (n = 7-28) by Cs+ sputtering of graphite
Phys. Rev. Lett. 65, 625 (1990)
J. Am. Chem. Soc. 113 , 6795 (1991)
Washington State University
Pacific Northwest National Laboratory
Experimental:
Mass spectrometry observations (70’)
Compton et al.: first observation of Cn2- (n = 7-28) (1990)
C602-: Coe et al. and Compton et al. (91’)
Kebarle, Lau, etc: electrospray (mid-90’s)
Theoretical: (1990’s)
Boldyrev/Gutsev (J. Phys. Chem. 94, 2256, 1990)
high EA species; MkXk+1- or (MX)kX-, stable dianions MkXk+2
2-
Cederbaum (Scheller, Compton & Cederbaum, Science 270, 1160, 1995)
Simons/Boldyrev/Gutowski (Acc. Chem. Res. 29, 497, 1996)
Ortiz
Landman
…
Prior research on multiply-charged anions
Washington State University
Pacific Northwest National Laboratory
Multiply-charged anionsare common in the condensed phase
• Simple oxo-anionsSO4
2-, CO32-, PO4
3-, C2O42-, S2O8
2-,
Si2O52-, CrO4
2-, Cr2O72-, VO4
3-, RuO43-…
• Inorganic and organometallic multiply- charged anionsMX4
2-, MX62-, (X = Metal, X = halides)…
• Organic multiply-charged anions
• Biomolecules
Washington State University
Pacific Northwest National Laboratory
Electrospray IonizationInterface between solution and gas phase
John B. Fenn et al. J. Phys. Chem. 88, 4451 & 4671 (1984): Nobel Prize 2002
-HV
Electrospray Capillary
Heated Desolvation
Capillary Skimmer
Mn- Mn- beam
Evaporation Breakup
Charged droplets
Kebarle, Lau, etc: ESI MS of MCA (mid-90’s)
Washington State University
Pacific Northwest National Laboratory
Photodetachment Spectroscopy Facility for Multiply Charged Anions
2.5m(TOF-MS)
Einzel-1
Syringe
Desolvation Capillary
4m
(M
TO
F-P
ES
)
ES
I S
ou
rce
Einzel-2
Ion Guide
Ion Trap
Ion Extraction
Mass Gate &
Decelerator
Ion Detector
Electron Detector
eee
Wang, Ding, Wang, & Barlow Rev. Sci. Instrum. 70, 1957-1966 (1999)
Washington State University
Pacific Northwest National Laboratory
Washington State University
Pacific Northwest National Laboratory
Solution-phase chemistry in the gas phaseUnique properties of multiply-charged anions
Electronic structure of solution anions and complexes in the gas phase
Solvation and solvent stabilization of complex and multiply-charged anions
Probing the electronic structure of Fe-S clusters, complexes and Fe-S proteins
Re2Cl82-, S2O8
2-, Cr2O72-, H2P2O7
2-, Ru6(CO)182-, ZrF6
2-, ML62- (M = Re, Os, Ir, Pt), …
J. Chem. Phys. 111, 4497 (1999); 112, 6959 (2000); J. Am. Chem. Soc. 112, 2096 (2000); 112, 2339 (2000);J. Phys. Chem. A 104, 4429 (2000); 105, 10468 (2001); J. Am. Chem. Soc. 122, 8305 (2000)…
SO42-(H2O)n, C2O4
2-(H2O)n, NO3-(H2O)n, F-(H2O)n, -O2C-(CH2)x-CO2
-(H2O)n, … Science 294, 1322 (2001); J. Chem. Phys. 113, 10837 (2001); 115, 2889 (2001); 116, 561 (2002);J. Phys. Chem. A 106, 7607 (2002); J. Am. Chem. Soc. 124, 10182 (2002); JACS 126, xxx (2004)…
Phys. Rev. Lett. 89, 163401 (2002); J. Phys. Chem. A 107, 1703 (2003); 107, 2821 (2003); 107, 2898 (2003); J. Phys. Chem. A 107, 4612 (2003); J. Am. Chem. Soc. 125, 14072 (2003)…
Nature 400, 245 (1999); Phys. Rev. Lett. 81, 2667 (1998); 81, 3351 (1998); J. Chem. Phys. 110, 3635 (1999); Phys. Rev. Lett. 83, 3402 (1999); J. Phys. Chem. A 104, 1978 (2000); Chem. Phys. Lett. 307, 391 (1999);…
AB2-
AB-EB
hKE
AB2-AB-
- EB
h KE
AB2- --> AB- + e-
RAB-- e-
E
FeS
S
S
S
L
L
L
L
FeS
S
S
S
L
L
L
LFe
S
S
Fe S
S Fe
S Fe
Fe S
SLS L
SL
S L
Washington State University
Pacific Northwest National Laboratory
Current experimental effort on multiply charged anions
Compton: Coulomb barrier, electron attachment (ESI)
Kappes:PES, laser detachment, lifetime in a Penning trap ESI/Laser ablation
Denmark group (Nielsen, Andersen, Hvelplund): electron scattering, charge transfer in storage ring (ESI)
Mainz group (Herlert, Schweikhard):Multiply charged anion formation in a Penning trap
Neumark/Woste/Meijer: IR of SO42-(H2O)n-
Wiliams: MS and IR of SO42-(H2O)n-
Dessent ……
ESI is gaining popularity as a powerful ion source not just for analytical mass spectrometry, but also for physical chemistry and spectroscopy
Washington State University
Pacific Northwest National Laboratory
Photoelectron spectroscopy of singly and multiply-charged anions
Ek Eb
= Eb + Ek h
A
B
C D E F
Ele
ctro
n A
ffin
ity
Eb
h
Eb
Ek
X M
X M- Mn-
M(n-1)-
M- h
M e- + 1
1
+ Mn- M(n-1)- e- 2
2
h
Washington State University
Pacific Northwest National Laboratory
E
RAB-e-
Singly Charged Anions:
AB- AB + e-h
Attractive (Polarization/Dipole)
Multiply Charged Anions:
AB2- AB- + e-h
(Repulsive)
RAB-- e-
E
Difference between photodetachment of singly and multiply-charged anions
Washington State University
Pacific Northwest National Laboratory
AB2-AB-Meta-Stable Dianion
- EB
h KE
h h
2
AB2-
AB-
EB
Stable Dianion
1
hKE
Repulsive coulomb barrier (RCB) and negative electron binding energies
Washington State University
Pacific Northwest National Laboratory
The first PES of a doubly charged anion: Direct observation of the RCB
Wang, Ding & Wang, Phys. Rev. Lett. 81, 3351 (1998)
Citrate
355 nm
266 nm
Washington State University
Pacific Northwest National Laboratory
C
C
C
C
C
OO
OO
H H H H
1.54
1.36
109
H H
C
C
C
C
OO
C
OO
H H H H
H H
C
H H
C
C
C
C
OO C
OO
H H H H
H H
C
CH H
H H
C
C
C
C
OO
C
OO
H H H H
H H
C
H H
CH H
C
H H
C
C
C
C
OO C
OO
H H H H
H H
C
CH H
H H
C
CH H
H H
C
C
C
C
OO
C
OO
H H H H
H H
C
H H
CH H
C
H H
CH H
C
H H
C
C
C
C
OO C
OO
H H H H
H H
C
CH H
H H
C
CH H
H H
C
C
C
C
OO
C
OO
H H H H
H H
C
H H
CH H
C
H H
CH H
C
H H
C
CH H
H H
CH H
C
H H
-OOC(CH2)nCOO-
n
3
4
5
6
7
8
9
10
-OOC(CH2)nCOO-
n=3
n=5
n=6
n=4
n=7
n=9
n=10
n=8
0 1 2 3Binding Energy (eV)
355nm
0 1 2 3 4Binding Energy (eV)
n=3
n=5
n=6
n=4
n=7
n=9
n=8
n=10
-OOC(CH2)nCOO-
266nm
Re
lati
ve
Ele
ctr
on
In
ten
sit
y
(a) (b)X A X
Wang, Ding, Wang & Nicholas Phys. Rev. Lett. 81, 2667-2670 (1998)
266 nm 355 nm
Intramolecular coulomb repulsion and RCB
Wang, Ding, Wang & Nicholas, Phys. Rev. Lett. 81, 2667 (1998)
Washington State University
Pacific Northwest National Laboratory
0.00 0.05 0.10 0.15(Å-1)1/rn
0.0
0.5
1.0
1.5
2.0
2.5
3.0
EB
X &
RC
B (
eV)
89 7 345610n
EBX (eV) = 3.21(4) - 16.7(3) rn (Å)
RCB(eV) = 0.00(5) + 16.8(3)
rn (Å)
Wang, Ding, Wang & NicholasPhys. Rev. Lett. 81, 2667 (1998) EB + RCB = constant = 3.2 eV !
= electron binding energy of R-CO2–
Intramolecular coulomb repulsion and RCB
C—–(CH2)n—–CO
O
O
OΘ Θ
rn
r
RCB = e2/r = 14.4/r (eV.Å)
Washington State University
Pacific Northwest National Laboratory
-2 -1 0 1 2 3 4 5Binding Energy (eV)
-2 -1 0 1 2 3 4 5Binding Energy (eV)
X
AB
X
X
AB
X
266 nm
193 nm
266 nm
193 nm
[CuPc(SO3)4H]3-[CuPc(SO3)4]4-
Observation of negative electron binding energies:photoelectron spectra of [CuPc(SO3)4]4- and [CuPc(SO3)4H]3-
X. B. Wang & L. S. Wang, Nature 400, 245 (1999)
1
2
3
4
R12 = 12.47 Å
5
R13 = 14.68 Å R14 = 8.53 Å R23 = 14.37 Å R24 = 17.10 Å R34 = 14.37 Å R15 = 6.50 Å R25 = R35 = R45 = 8.66 Å
Cu S ON C H
Kappes et al., isomer-dependent life times: J. Phys. Chen. A 107, 794 (2003)
Washington State University
Pacific Northwest National Laboratory
• Isolated SO42- and PO4
3- Anions Do Not Exist
– Boldyrev & Simons, J. Phys. Chem. 98, 2298 (1994)
– SO42- ----> SO4
- + e-, -1.6 eV
• Blades & Kebarle, J. Am. Chem. Soc. 116, 10761 (1994)
– ESI of Na2SO4 solution
– Observed SO42-(H2O)n, n = 4-16
• Questions:
– Minimum number of H2O needed to stabilize SO42-
– How is SO42- solvated?
– Inside or outside? – Solvation shell?
Solvation and solvent stabilization of multiply-charged anions
Washington State University
Pacific Northwest National Laboratory
50 60 70 80 90
HSO4- SO4-
n = 3 4 5 6 7 8 9 10 12 14 16
x3
(a)
Time of Flight (s) 115 120 125 130
100 105 110 115
20 22 24 26 28 30
36 38 40 34 32 30
(b)
(c)
ESI Mass Spectra of SO42-(H2O)n
Blades & KebarleJ. Am. Chem. Soc. 116, 10761 (1994)
Washington State University
Pacific Northwest National Laboratory
10
9
8
7
6
5
4
Na+(SO42-)
6 0 1 2 3 4 5 Binding energy (eV)
HSO4-(H2O)n-1OH- X J. Chem. Phys. 113, 10837 (2000)
X A
X
A
PES of SO42–(H2O)n and solvent stabilization of SO4
2–
1 3 5 7 9 11 13Number of H2O molecules
-1
0
1
2
3
4
Bin
din
g E
ner
gy
(eV
)
Wang, Nicholas & Wang, J. Chem. Phys. 113, 10837 (2000)
VDE
ADE
Washington State University
Pacific Northwest National Laboratory
1.88
1.
92
1.98
1.93
1.96
1.99
1.99
1.97
2.08
1.92
1.94
1.94
1.98
2.06 2.11
2.10
2.06
1.80
1.99
2.09
Wang, Nicholas & Wang, J. Chem. Phys. 113, 10837 (2000)
Calculated structures of SO42-(H2O)n, n = 1-6
Washington State University
Pacific Northwest National Laboratory
PES of SO42-(H2O)n, n = 4-40
SO42-(H2O)n
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
0 1 2 3 4 5 6 7Binding Energy (eV)
SO42-(H2O)n
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
0 1 2 3 4 5 6 7Binding Energy (eV)
Wang, Yang, Nicholas & Wang Science 294, 1322 (2001)
Large hydrated clusters:a single sulfate dianion in
the center of a water droplet
Washington State University
Pacific Northwest National Laboratory
Recent IR studies on SO42-(H2O)n
J. Chem. Phys. 125, 111102 (2006)Zhou, Santambrogio, Brummer, Moore,
Woste, Meijer, Neumark & Asmis
IR for n = 3-24 using FELIX at 17 K
J. Am. Chem. Soc. 129, 2220 (2007) Bush, Saykally & Williams
IR for n = 6 at OH stretching at 130 K
Washington State University
Pacific Northwest National Laboratory
Isomers of SO42–(H2O)n
J. Am. Chem. Soc. 129, 2220 (2007) Bush, Saykally & Williams
Gao & Liu, J. Chem. Phys. 123, 224302 (2005)
Washington State University
Pacific Northwest National Laboratory
Dissociation of SO42–(H2O)n for n = 3-17 (BIRD)
Wong & Williams J. Phys. Chem. A 107, 10976 (2003)
Two dissociation Channels:
SO42–(H2O)n → SO4
2–(H2O)n-k + kH2O (1)
→ HSO4– (H2O)k + (H2O)mOH– (2)
For n = 3, 4: (2) exclusively
n = 5, 6: both (1) and (2), but for n = 5, (2) dominates, and for n = 6, (1) dominates
n ≥ 7: (1) exclusively
Washington State University
Pacific Northwest National Laboratory
Size-dependent charge separation reactions of SO4
2–(H2O)n for n = 3-7
Gao & Liu, J. Chem. Phys. 123, 224302 (2005)
Washington State University
Pacific Northwest National Laboratory
Second generation ESI-PES apparatus at low-temperatures
5 m
Washington State University
Pacific Northwest National Laboratory
Radiation shield 1st stage 50K
Adapter
ARS: DE-204 2nd stage 2.0 W@10K 9.0 W@20K Dia. 1.17 O.D.
AA
Sapphire
1/8
sst
tu
be
1.17
Indium foilRotable
Sealed by Indium wire
The low-temperature ion trap
Ion entrance Ion exit
Cold Head10 K
Rotatable
Washington State University
Pacific Northwest National Laboratory
Washington State University
Pacific Northwest National Laboratory
Wang, Woo & Wang, J. Chem. Phys. 123, 051106 (2005)
Hotbands
Vibrationally-cold photoelectron spectrum of C60–
Washington State University
Pacific Northwest National Laboratory
Vibrationally resolved PES of cold C70-
2.0 3.0 4.0 5.0 6.0
Binding Energy (eV)
(a) 355 nm
(b) 266 nm
(c)193 nm
1.55 eV
Chem. Phys. Lett. 233, 52 (1995)
EA(C70) =
2.765 ± 0.010 eV
EA(C60) =
2.683 ±
0.008 eV
EA(C60) = 2.666 ± 0.001 eVEA(C70) = 2.676 ± 0.001 eV
Too low!!!
Washington State University
Pacific Northwest National Laboratory
Photoelectron spectroscopy of cold C702-
0.0 1.0 2.0 3.0 4.0
Binding Energy (eV)
(b) 355 nm
(c) 266 nm
(a) 532 nm
1.55 eV
2.0 3.0 4.0 5.0 6.0
Binding Energy (eV)
1.55 eV
0.0 1.0 2.0 3.0 4.0
C702-
C702-
C70-
EA2(C70) = ADE(C702-) = 0.02 eV
Wang, Woo, Huang, Kappes & Wang, Phys. Rev. Lett. 96, 143002 (2006)
Washington State University
Pacific Northwest National Laboratory
Electron-electron repulsion in C702-
HOMO e1”
LUMO
e1”
a1”
7.94
7.14
Å
Å
EA1(C70) – EA2(C70) =
2.765 – 0. 02 = 2.745 eV
e2/r =
1.8 to 2.0 eV
Wang, Woo, Huang, Kappes & Wang, Phys. Rev. Lett. 96, 143002 (2006)
Washington State University
Pacific Northwest National Laboratory
AcknowledgmentsAcknowledgments
Dr. Xue-Bin Wang
Dr. Jie Yang
Dr. Chuan-Fan Ding (Fudan U.)
Dr. Xin Yang (Fudan U.)
Dr. You-Jun Fu (U. Kentucky)
Dr. Hin-Koon Woo (Scripps)
Dr. Tom Waters (U. Melbourne)
Supported by: DOE, NSF & Guggenheim Foundation
Collaboration:
J. B. Nicholas (theo)
M. M. Kappes (fullerenes)