Vibrational Analysis of Hydrated Halide Clusters Spectra

Meng Huang and Anne B. McCoyDepartment of Chemistry and BiochemistryThe Ohio State Univerisity

IntroductionHydrated Halide Clusters

Provide good model for studying the interactions between ions and molecules such as intramolecular hydrogen-bonding

May provide explanations to important processes such as the transport of ions through membranesImportant clusters in aqueous chemistry

Assignment to the experimental spectrum taken by argon predissociation spectra[1]

[1] Horvath. S., McCoy, A. B., Elliot, B. M.,Weddle, G. H., Roscioli, J. R., and Johnson, M. A.,  J. Phys. Chem. A, 114, 1556–1568 (2010). 

1000 1200 1400 1600 1800 3000 3200 3400 3600 3800

Photon Energy, cm-1

1

2

3

4

5 6

7

9

10

11

12

131415

1617

188

MotivationI-(H2O) Argon Predissociation Spectra [1]

Peak Position, cm-1

1 (2noop) 1098.32 1115.53 1141.9

4 (nHOH) 1639.35 (nHOH+nip) 1799.06 (nHOH+nip) 1890.2

7 (2nHOH) 3245.88 (2nHOH+nOX) 3367.1

9 (nOHb) 3392.810 (nOHb) 3422.2

11 3475.012 (nOHb+nOX) 3524.213 (nOHb+nOX) 3552.1

14 3625.815 3648.9

16 (nOHf) 3691.917 (nOHf) 3705.6

18 3765.1

[1] Horvath. S., McCoy, A. B., Elliot, B. M.,Weddle, G. H., Roscioli, J. R., and Johnson, M. A.,  J. Phys. Chem. A, 114, 1556–1568 (2010). 

Molecular Geometry

𝜈𝑂𝐻 𝑏

Equilibrium Transition State𝜈𝑂𝐻 𝑓

𝜃ipx

y 𝜈as𝜈s

𝜈ip

𝜃ip=0𝜈ip

Reduced Dimensional AnalysisHamiltonian and Dipole Moment

𝜇𝑖 (𝜃 𝑖𝑝)=𝜇𝑖 ,0 (𝜃𝑖𝑝 )+𝜕𝜇𝑖

𝜕∆𝑟1(𝜃 𝑖𝑝) ∆𝑟 1+

𝜕𝜇𝑖

𝜕∆𝑟 2(𝜃𝑖𝑝 ) ∆𝑟2

ħ=1

Reduced Dimensional AnalysisTheoretical Details

Potential Energy Surface/Force Constantsab initio calculation with MP2/aug-cc-pVTZ-(PP) level of theory

Dipole Moment/First order Dipole Derivativeab initio calculation with MP2/aug-cc-pVTZ-(PP) level of theory

Basis Sets for Linear Variation Calculation Stretch Mode : Harmonic OscillatorIn-plane Bend : Grid Basis Set (DVR)

Simulation of SpectraLorentzian (FWHM = 5 cm-1)

I-(H2O)/I-(D2O) Spectra

3400 3500 3600 3700 3800 3900 4000

Wavenumber

I-(H2O) Simulation

3200 3300 3400 3500 3600 3700 3800

I-(H2O) Experiment

2400 2500 2600 2700 2800 2900

Wavenumber

I-(D2O) Simulation

2300 2400 2500 2600 2700 2800

I-(D2O) ExperimentνOHb

νOHb+ νOX

νOHb+ νip

νOHf2νHOH

νOHb

νOHfνOHb+ νip

νODb

νODb+ νip

νODf

νODf

νODb

2νDOD

3400 3500 3600 3700 3800 3900 4000

Wavenumber

3200 3300 3400 3500 3600 3700 3800

Combination Band νOHb

+ νip

Stretch – Bending Coupling

-120 -90 -60 -30 0 30 60 90 120

3500

3600

3700

3800

3900

4000

Fre

quen

cy (

cm-1)

ip

Normal Mode Frequencies of O-H Stretch Modes in I-(H2O)

-90 -60 -30 0 30 60 900

200

400

600

800

1000

Ene

rgy

(cm

-1)

ip

Potential energy surface and energy levels of the in-plane bending mode for I-(H2O)

Tunneling Splitting

-90 -60 -30 0 30 60 904500

5000

5500

12000

12500

13000

13500

Effe

ctiv

e E

ne

rgy

(cm

-1

)

ip

Combination Band νOHb+ νip

The increase of the barrier height leads to the overlap between ground state wavefunction and bending excited state. The tunneling splitting also decreases dramatically from ground state to excited state.

νOHb=1

νOHb=0

νip=1

νip=0

νip=0

νOHb νOHb + νip

Spectra of X-(H2O)

3200 3400 3600 3800 4000

Wavenumber

3200 3400 3600 3800 4000

3200 3400 3600 3800 4000

3000 3200 3400 3600 3800

Wavenumber

3000 3200 3400 3600 3800

3000 3200 3400 3600 3800

Experimental Spectrum of X-(H2O) Calculated Spectrum of X-(H2O)

νOHb

νOHb

νOHb

νOHb

νOHb

νOHb

νOHf

νOHf

νOHf

νOHf

νOHf

νOHf

νOHb+ νip

νOHb+ νip

νOHb+ νip

νOHb+ νip

νOHb+ νip

νOHb+ νip2νHOH

2νHOH

2νHOH

Cl-(H2O) Cl-(H2O)

Br-(H2O)

I-(H2O)

Br-(H2O)

l-(H2O)

3000 3200 3400 3600 3800

Wavenumber

3000 3200 3400 3600 3800

3000 3200 3400 3600 3800

Spectra of X-(D2O)

2300 2400 2500 2600 2700 2800 2900

Wavenumber

2300 2400 2500 2600 2700 2800 2900

2300 2400 2500 2600 2700 2800 2900

2400 2500 2600 2700 2800 2900 3000

Wavenumber

2400 2500 2600 2700 2800 2900 3000

2400 2500 2600 2700 2800 2900 3000

Experimental Spectrum of X-(D2O) Calculated Spectrum of X-(D2O)

Cl-(D2O) Cl-(D2O)

Br-(D2O) Br-(D2O)

I-(D2O) I-(D2O)

νODf

νODf

νODf

νODf

νODf

νODf

νODb

νODb

νODb

νODb

νODb

νODb

2νDOD

2νDOD

2νDOD νODb+ νip

νODb+ νip

νODb+ νip

Comparison among Different Hydrated Halide Clusters

-90 -60 -30 0 30 60 901000

1500

2000

2500

3000

3500

4000

V0+

ZP

E (

cm-1)

ip

Cl-(H2O)

Br-(H2O)

I-(H2O)

509 cm-1

402 cm-1

208 cm-1

The comparison among different calculated hydrated halide clusters spectra provides expected result.

SummaryReduced dimensional analysis show qualitative agreement with the experimental spectrum

Doublet structure in the O-H stretch transition is attributed to the double well potential in in-plane bending modeOne transition is assigned to be combination band of O-H stretch and in - plane bending mode Comparison among calculated spectra of different hydrated halide clusters also show the expected result

AcknowledgementDr. Anne B. McCoy

Andrew Petit

Zhou Lin

Bernice Opoku-

Agyeman

Laura Dzugan

Bethany Wellen

Jason Ford

Thank you!