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Gyeongsang National University, Jinju, Korea
Myong Yong Choi, Seung Jun Lee
Hydrated HCl Complexes, Hydrated HCl Complexes, (HCl)(HCl)mm(H(H22O)O)nn, in , in
Helium Nanodroplets:Helium Nanodroplets:HClHCl Stretching Modes Stretching Modes
The 65th International Symposium on Molecular Spectroscopy, June 21-25, 2010
University of Southern California, Los Angeles, CA 90089, U.S.A.Dimitry Skvortsov and Andrey F. Vilesov
( )m( )n
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(-3.2)
(w/ ZPE in kJ/mol)MP2/aug-cc-pVDZ
(12.5)
(0.4)
(2.5)
(0)
n = 1 2 3 4
Calculations of Calculations of HCl-Water HCl-Water Clusters Clusters
The clear assignment of the hydrated HCl with four water molecules is not still available through spectroscopy.
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Calculated spectra of HCl-(HCalculated spectra of HCl-(H22O)O)nn
1500 2000 2500 3000 3500 40000
500
Wavenumber (cm-1)
0
2000
0
2000
0
2000
0
2000
MP2/aug-cc-pVDZ
H3O+
b-OH
f-OH
HCl
b-OH (H2O)n
5 4 3 2
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Science, 324, 1545 (2009)
Recent assignment of the Recent assignment of the S5S5 band in He droplets to band in He droplets to
HH33OO++-(H-(H22O)O)33-Cl-Cl-- +
-
Tiny droplets of acid. (Credit: Image courtesy of Ruhr-
Universitaet-Bochum)
S5S5
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m/z=73
Recent assignment of the Recent assignment of the S5S5 band in He droplets to band in He droplets to
HH33OO++-(H-(H22O)O)33-Cl-Cl-- +
-
(HCl)m(H2O)n
n=4
m=1
n=10
S5S5
Science, 324, 1545 (2009)
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Laser Depletion SpectroscopyLaser Depletion Spectroscopy
HClPick-up
Chamber
Main chamber
Closed-cyclerefrigerator
Nozzle
LN2 trap
Power meter
QuadrupoleX-Y-ZH2O
pick-up cell
Nd:YAG
1064 nm, 750 mJ, 7 ns
OPO/OPA
2050-6000 cm-1
≈ 1 m
-2 0 2 4 60
5
10
Sig
nal,
mV
Time, ms
Laser Pulse
m/e > 6
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Overview Spectra in He dropletsOverview Spectra in He droplets
2600 2800 3000 3200 3400 3600 3800
Neat (HCl)m and (H2O)n
clusters
2600 2800 3000 3200 3400 3600 3800
wavenumber, cm-1
Mixed HCl and H2Oclusters
Skvortsov, Choi, Vilesov, unpublished 2007
HCl b-OH f-OH
S5S5
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2650 2700 2750 2800 2850 2900 2950
<500>
<20>
<0.25>
<1.0>
<2.0>
<4.0>
Depletion signal
Wavenumber, cm-1
<8.0>
*
**
(e)
(g)
(d)
(f)
(c)
(b)(a)
1
234
55
1
2
34
55
6 6
IR Spectra of (HCl)IR Spectra of (HCl)mm Clusters Clusters
Skvortsov, Choi, Vilesov, JPCA 2007
m =
(HCl)1(H2O)1 0 1 2 3 4 5
MonomerDimer:
Dimer:
Trimer
Nor
mal
ized
sig
nal
Pressure, 10-5 mbar
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Assignment of the clusters (HCl)Assignment of the clusters (HCl)mm(H(H22O)O)nn using pressure using pressure
dependence of the band intensity ratios: dependence of the band intensity ratios: IInn//II11
0.5 0.75 1 2.50.01
0.1
1
Slope = 2.8n = 4
Slope = 1.7n = 3
Lo
g(I
n/I
1)
Log(<H2O>)
Slope = 0.86n = 2
n is somewhat less than integerSub-linear dependence at large Z:- droplet size distribution,- decreasing of the droplet size- scattering of the beam- downstream pickup
According to Poisson dependence:
Log(In/I1) = (n-1)*Log(Z) + f(n)
n – Cluster sizeZ – Average number of collisions or pickup pressure
Water: difficult to reach zero pressure,Important, because otherwise Poisson does not workand interpretation of the pickup pressure results is ambiguous
2600 2800 3000 3200 3400 3600 3800
wavenumber, cm-1
Neat and mixed HCl and H2Oclusters
Skvortsov, Choi, Vilesov, unpublished 2007
HCl-H2O
*
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2650 2700 2750 2800 2850 2900 2950
<500>
<20>
<0.25>
<1.0>
<2.0>
<4.0>
Depletion signal
Wavenumber, cm-1
<8.0>
*
**
(e)
(g)
(d)
(f)
(c)
(b)(a)
1
234
55
1
2
34
55
6 6
0 1 2 3 4 5
MonomerDimer:
Dimer:
Trimer
Nor
mal
ized
sig
nal
Pressure, 10-5 mbar
IR Spectra of (HCl)IR Spectra of (HCl)mm Clusters Clusters
Skvortsov, Choi, Vilesov, JPCA 2007
m =
0.25 0.5 0.75 1 2.5
0.01
0.1
1
Slope = 3.6m=5
Slope = 2.6m=4
Slope = 1.9m=3
Slope=0.97m=2
Lo
g(I
m/I
1)
Log(<HCl>)
m=1
Log(Im/I1) = (m-1)*Log(Z) + f(m)
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Overview Spectra in He dropletsOverview Spectra in He droplets
2600 2800 3000 3200 3400 3600 3800
2600 2800 3000 3200 3400 3600 3800
wavenumber, cm-1
Mixed HCl and H2Oclusters
Neat (HCl)m and (H2O)n
clusters
Skvortsov, Choi, Vilesov, unpublished 2007
HCl b-OH f-OH
m =
4 2
3
12
n =
66
5 4 3 2
1
2
2
3+
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Calculated spectra of HCl-(HCalculated spectra of HCl-(H22O)O)nn
1500 2000 2500 3000 3500 40000
500
Wavenumber (cm-1)
0
2000
0
2000
0
2000
0
2000
MP2/aug-cc-pVDZ
H3O+
b-OH
f-OH
HCl
b-OH (H2O)n
5 4 3 2
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HCl-stretch bands in (HCl)HCl-stretch bands in (HCl)mm(H(H22O)O)nn clusters clusters
at different Z(at different Z(HClHCl))
1 2
0.1
1
2755 cm-1
2706 cm-1
2670 cm-1
2568 cm-1
2774 cm-1
Log
(Im/I
1)
Log(<HCl>)
Slope: 0.83m = 2
Slope: 1.72m = 3
S5S5
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HCl-stretch bands in (HCl)HCl-stretch bands in (HCl)mm(H(H22O)O)nn clusters clusters
at different Z(at different Z(HH22OO))
1 2 30.1
1
2755 2706 2670 2774
slope = 0.06n = 1
slope = - 0.13n = 1
slope = - 0.06n = 1
Lo
g(I
n/I
1)
Log(<H2O>)
slope = 0.91n = 2
S5
S5
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Assignment of the H-Cl stretching bands Assignment of the H-Cl stretching bands
2300 2400 2500 2600 2700 2800 2900
wavenumber, cm-1
2:2
HCl:H2O
2:04:0 3:0 2:0
In gasFarnik, Wiemann, Suhm, JCP 2003
S31:1
S2NA
S5NA
S4NA
S9NA
S6NA
S12:1
S82:1
S7NA
S101:2
2:1 overlapped with 4:01:1
2:11:2 or 2:2
3:13:1
??
??
S5S5
(HCl)m =
OO
XX
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1.88 D
6.26 D
+ + +
_ _ _ _ _
+ +
2 1
0 10 20 30 40 50 60 70 80 90 1000.0
0.5
1.0
1.5
2.0
2.5
A(p
ara
.)/A(z
ero
)
electric field (kV/cm)
0o
90o
VTMA
+5o
2
0 10 20 30 40 50 60 70 80 90 100
electric field (kV/cm)
0o
90o
VTMA
+5o
1
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0.0
0.5
1.0
1.5
2.0
0 10 20 30 40 50 60 70 80 90
0.0
0.5
1.0
1.5
A(p
ara
.)/A(z
ero)
electric field (KV/cm)
0.0
0.5
1.0
1.5
2.0
0 10 20 30 40 50 60 70 80 90
0.0
0.5
1.0
1.5
A(p
ara
.)/A(z
ero)
electric field (KV/cm)
+ + +
_ _ _ _ _
+ +
1
2
440 [NH2(AS)]420 [N9H]
800 [N1H]
310 [NH2(SS)]
290 [NH2(AS)]
730 [N7H]
470 [N1H]
830 [NH2(SS)]
Electric Field Dependence of Different DipolesElectric Field Dependence of Different Dipoles
1.88 D
6.26 D
6.26 D
1.88 D
0.0
0.5
1.0
1.5
2.0
0 10 20 30 40 50 60 70 80 90
0.0
0.5
1.0
1.5
A(p
ara
.)/A(z
ero)
electric field (KV/cm)
310 [NH2(SS)]
290 [NH2(AS)]
M. Y. Choi and R. E. Miller, J. Am. Chem. Soc. 2006, 128, 7320.
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0 10 20 30 40 50
0.6
0.8
1.0
1.2
1.4
1.6
I(fie
ld o
n)/I(
field
off)
Electric Field (kv/cm)
Predicted electric field dependence of Predicted electric field dependence of
the Hthe H33OO++-(H-(H22O)O)33-Cl-Cl- - bandband
S. Flynn, A. Morrison, T. Liang, G. Douberly, unpublished result (2010)
0 10 20 30 40 50
0.6
0.8
1.0
1.2
1.4
1.6
I(fie
ld o
n)/I(
field
off)
Electric Field (kv/cm)
EStark
ELaser
EStark
ELaserValues used to reproduce Experimental field dependence:p = 2.76 D, VTMA = 58.2O
p = 2.76 DVTMA = 58.4O
p = 4.22 DVTMA = 36.5O
Symmetric stretch
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ConclusionsConclusions
- Observation of sharp infrared spectrum of [H(H2O)4]+Cl- seems illusive
- Calculated spectra may be at large variance with experiment
- Need for more Mutual Tests between Theory and Experiment
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AcknowledgementsAcknowledgements
Andrey F. Vilesov Group at USC
GNU Laser Spectroscopy Lab.
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m/z=73
Recent assignment of the Recent assignment of the S5S5 band in He droplets to band in He droplets to
HH33OO++-(H-(H22O)O)33-Cl-Cl-- +
-
(HCl)m(H2O)n
n=4
m=1
n=10
M=108: ??
(HCl)1(H2O)4
or (HCl)2(H2O)2
Science, 324, 1545 (2009)