Post on 05-Jan-2016
Adam J. FleisherJustin W. YoungDavid W. Pratt
Department of ChemistryUniversity of Pittsburgh
Internal dynamics of water attached to a photoacidic substrate: High resolution electronic spectroscopy ofβ-naphthol-water in the gas phase.
TA-03
Solvent in Motion• Rotationally resolved
electronic spectroscopy– A tunneling splitting
provides a measure of the barrier to internal rotation.
– This splitting is a function of both the S0 and S1 barriers.
S0 S1
torsional coordinate
cm-1 cm-1
torsional coordinate
Charge in Motion – MG042-naphthol-ammonia 2-naphthol-water
M.J. Frisch et. al. Gaussian 03 (Gaussian, Inc., Wallingford, CT, 2004).
CW Tunable UV Laser
Argon Ion Laser (7 W)
Ring Dye Laser (85 mW)
Frequency Doubler
Reference Station
I2 tube
Tunable UV laser beam (300 µW)
Monochromator
Interferometer
Molecular Beam Machine
W. A. Majewski, J. F. Pfanstiel, D. F. Plusquellic, and D. W. Pratt, in Laser Techniques in Chemistry, edited by A. B. Myers and T. Rizzo (Wiley, New York, 1995), 101.
aa
eff PFWAA 2
Inertial ParametersA (σ = 0) B (σ = 1)
S0
Aeff (MHz) 1725.9(1) 1724.9(1)
Beff (MHz) 548.1(1) 548.1(1)
Ceff (MHz) 416.6(1) 416.8(1)
ΔIeff (amu Å2) -1.781 -2.609
S1
Aeff (MHz) 1687.4(1) 1686.3(1)
Beff (MHz) 553.4(1) 553.3(1)
Ceff (MHz) 417.3(1) 417.5(1)
ΔIeff (amu Å2) -1.741 -2.648
Origin (MHz) 915333681(30) 915339355(30)
# lines 141 458
OMC (MHz) 4.1 5.0
L/G LW (MHz) 9/25 9/25
Rel. Intensity 1 3
a M.J. Frisch et. al. Gaussian 03 (Gaussian, Inc., Wallingford, CT, 2004).
a
b
Origin of Splitting
Energy
S0
S1
A (1)
B (3)
Qualitative Experimental Conclusions:• V2 in S0 is greater than V2 in S1
• The two hydrogen atoms of water must exchange with a 180° movement along the torsional coordinate
Quantitative Measures:• V2 in each state is determined assuming a
rotation about the b-axis of water• Higher order terms (V4, V8) can be
estimated with the aid of ab initio internal rotation pathways
• A-B energy level splitting in both S0 and S1 can be determined
Barrier Heights (I)
F
VsW
WWPF
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v
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22
200
201
200
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Calculation of W(2) from available data tables determines V2 in each electronic state.a
S0 S1
ΔAvσ = A01 – A00 (MHz) 1.0 1.1
ΔBvσ (MHz) 0.1 0.1
ΔCvσ (MHz) -0.2 -0.2
tunneling splitting 5673 MHz (0.189 cm-1)
a D.R. Herschbach. J. Chem. Phys. 31, 91 (1959).
Barrier Heights (III)
2-naphthol-water phenol-water a
S0 S1 S0 S1
θRa (°) 14.5 b 29.2 9 9
F (GHz) 437.0 436.8 435 435V2 (cm-1) 206 182 180 130
ΔE(GHz) c 14 19 20 43
a G. Berden, W.L. Meerts, M. Schmitt, K. Kleinermanns, J. Chem. Phys. 104, 972, (1996).b from M05-2X/6-31+G* optimizationc W.H. Flygare, Molecular Structure and Dynamics. (Prentice-Hall, Inc., Englewood Cliffs, NJ, 1978).
Summary• Rotationally resolved electronic spectra of the
2-naphthol-water complex revealed internal motion.
• The results presented are a prerequisite for studying the cluster dipole moment, and therefore the solvent induced charge motion in each electronic state (MG-04).
• The complicated internal motion of water makes the decomposition of solvation interactions theoretically challenging (MG-04).
• Philip Morgan• Diane Miller
Marquette University
• Ryan Bird• Jessica Thomas• Casey Clements• Patrick Walsh
• Dr. David W. PrattUniversity of Pittsburgh
• Dr. David PlusquellicJB95 development
Acknowledgments (I)
Hamiltonian and Optics
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Inertial ParametersA (σ = 0) B (σ = 1)
S0
Aeff (MHz) 1725.9(1) 1724.9(1)
Beff (MHz) 548.1(1) 548.1(1)
Ceff (MHz) 416.6(1) 416.8(1)
ΔIeff (amu Å2) -1.781 -2.609
S1
Aeff (MHz) 1687.4(1) 1686.3(1)
Beff (MHz) 553.4(1) 553.3(1)
Ceff (MHz) 417.3(1) 417.5(1)
ΔIeff (amu Å2) -1.741 -2.648
Origin (MHz) 915333681(30) 915339355(30)
# lines 141 458
OMC (MHz) 4.1 5.0
L/G LW (MHz) 9/25 9/25
Rel. Intensity 1 3
Average Structural Constants
Theoretical Constants a
(6-31+G*)S0 M05-2X
A (MHz) 1725.4 1738.5
B (MHz) 548.1 554.1
C (MHz) 416.7 421.0
ΔI (amu Å2) -2.19 -2.34
S1 CIS
A (MHz) 1686.9 1692.5
B (MHz) 553.4 551.8
C (MHz) 417.4 416.9
ΔI (amu Å2) -2.18 -2.24
aa
eff PFWAA 2
a M.J. Frisch et. al. Gaussian 03 (Gaussian, Inc., Wallingford, CT, 2004).
Barrier Heights (III)
2-naphthol-water phenol-water a
S0 S1 S0 S1
θRa (°) 14.5 b 29.2 9 9
F (GHz) 437.0 436.8 435 435V2 (cm-1) 206 182 180 130
ΔE(GHz) c 14 19 20 43
a G. Berden, W.L. Meerts, M. Schmitt, K. Kleinermanns, J. Chem. Phys. 104, 972, (1996).b from M05-2X/6-31+G* optimizationc W.H. Flygare, Molecular Structure and Dynamics. (Prentice-Hall, Inc., Englewood Cliffs, NJ, 1978).
S0 HF / 6-31+G* Percent of V2 Modified Exp.
V2 (cm-1) 238 --- 206
V4 (cm-1) -28 -12 -24
V8 (cm-1) 6 2.5 5
ΔE(GHz) c 11 --- 16