gyeongsang national university, jinju, korea myong yong choi, seung jun lee hydrated hcl complexes,...

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

(-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.

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

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

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)

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

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Skvortsov, Choi, Vilesov, unpublished 2007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

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

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

*

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)

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+

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

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

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

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

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

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.

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

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

AcknowledgementsAcknowledgements

Andrey F. Vilesov Group at USC

GNU Laser Spectroscopy Lab.

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)