The fragmentation dynamics of gas phase phenol molecules following excitation at many wavelengths in the range 279.145λphot206.00nm have been investigated by H Rydberg atom photofragment translational spectroscopy. Many of the total kinetic energy release (TKER) spectra so derived show structure, the analysis of which confirms the importance of O–H bond fission and reveals that the resulting phenoxyl cofragments are formed in a very limited subset of their available vibrational state density. Spectra recorded at λphot248nm show a feature centered at TKER 6500cm1. These H atom fragments, which show no recoil anisotropy, are rationalized in terms of initial S1S0(π*π) excitation, and subsequent dissociation via two successive radiationless transitions: internal conversion to ground (S0) state levels carrying sufficient O–H stretch vibrational energy to allow efficient transfer towards, and passage around, the conical intersection (CI) between the S0 and S2(π1σ*) potential energy surfaces (PESs) at larger ROH, en route to ground state phenoxyl products. The observed phenoxyl product vibrations indicate that parent modes ν16a and ν11 can both promote nonadiabatic coupling in the vicinity of the S0S2 CI. Spectra recorded at λphot248nm reveal a faster, anisotropic distribution of recoiling H atoms, centered at TKER 12000cm1. These we attribute to H+phenoxyl products formed by direct coupling between the optically excited S1(π1π*) and repulsive S2(π1σ*) PESs. Parent mode ν16b is identified as the dominant coupling mode at the S1S2 CI, and the resulting phenoxyl radical cofragments display a long progression in ν18b, the C–O in-plane wagging mode. Analysis of all structured TKER spectra yields D0(HOC6H5)=30015±40cm1. The present findings serve to emphasize two points of wider relevance in contemporary organic photochemistry: (i) The importance of π1σ* states in the fragmentation of gas phase heteroaromatic hydride molecules, even in cases where the π1σ* state is optically dark. (ii) The probability of observing strikingly mode-specific product formation, even in “indirect” predissociations, if the fragmentation is driven by ultrafast nonadiabatic couplings via CIs between excited (and ground) state PESs.

1.
B. A.
Barry
,
M. K.
Eldeeb
,
P. O.
Sandusky
, and
G. T.
Babcock
,
J. Biol. Chem.
265
,
20139
(
1990
).
2.
D.
Creed
,
Photochem. Photobiol.
39
,
537
(
1984
);
D.
Creed
,
Photochem. Photobiol.
39
,
563
(
1984
);
D.
Creed
,
Photochem. Photobiol.
39
,
577
(
1984
).
3.
A. L.
Sobolewski
,
W.
Domcke
,
C.
Dedonder-Lardeux
, and
C.
Jouvet
,
Phys. Chem. Chem. Phys.
4
,
1093
(
2002
).
4.
A. L.
Sobolewski
and
W.
Domcke
,
J. Phys. Chem. A
105
,
9275
(
2001
).
5.
Z. G.
Lan
,
W.
Domcke
,
V.
Vallet
,
A. L.
Sobolewski
, and
S.
Mahapatra
,
J. Chem. Phys.
122
,
224315
(
2005
).
6.
G.
Berden
,
W. L.
Meerts
,
M.
Schmitt
, and
K.
Kleinermanns
,
J. Chem. Phys.
104
,
972
(
1996
).
7.
M.
Takayanagi
and
I.
Hanazaki
,
Laser Chem.
14
,
103
(
1994
).
8.
H. D.
Bist
,
J. C. D.
Brand
, and
D. R.
Williams
,
J. Mol. Spectrosc.
21
,
76
(
1966
).
9.
A.
Sur
and
P. M.
Johnson
,
J. Chem. Phys.
84
,
1206
(
1986
).
10.
R. J.
Lipert
,
G.
Bermudez
, and
S. D.
Colson
,
J. Phys. Chem.
92
,
3801
(
1988
).
11.
R. J.
Lipert
and
S. D.
Colson
,
J. Phys. Chem.
93
,
135
(
1989
).
12.
G.
Granucci
,
J. T.
Hynes
,
P.
Millie
, and
T. H.
Tran-Thi
,
J. Am. Chem. Soc.
122
,
12243
(
2000
).
13.
G. A.
Pino
,
C.
Dedonder-Lardeux
,
G.
Gregoire
,
C.
Jouvet
,
S.
Martrenchard
, and
D.
Solgadi
,
J. Chem. Phys.
111
,
10747
(
1999
).
14.
G.
Gregoire
,
C.
Dedonder-Lardeux
,
C.
Jouvet
,
S.
Martrenchard
,
A.
Peremans
, and
D.
Solgadi
,
J. Phys. Chem. A
104
,
9087
(
2000
).
15.
G.
Pino
,
G.
Gregoire
,
C.
Dedonder-Lardeux
,
C.
Jouvet
,
S.
Martrenchard
, and
D.
Solgadi
,
Phys. Chem. Chem. Phys.
2
,
893
(
2000
).
16.
S.
Ishiuchi
,
K.
Daigoku
,
M.
Saeki
,
M.
Sakai
,
K.
Hashimoto
, and
M.
Fujii
,
J. Chem. Phys.
117
,
7077
(
2002
);
S.
Ishiuchi
,
K.
Daigoku
,
M.
Saeki
,
M.
Sakai
,
K.
Hashimoto
, and
M.
Fujii
,
J. Chem. Phys.
117
,
7083
(
2002
).
17.
O.
David
,
C.
Dedonder-Lardeux
, and
C.
Jouvet
,
Int. Rev. Phys. Chem.
21
,
499
(
2002
).
18.
S.
Ishiuchi
,
K.
Daigoku
,
K.
Hashimoto
, and
M.
Fujii
,
J. Chem. Phys.
120
,
3215
(
2004
).
19.
J. A.
Syage
and
J.
Steadman
,
J. Chem. Phys.
95
,
2497
(
1991
).
20.
G.
Gregoire
,
C.
Dedonder-Lardeux
,
C.
Jouvet
,
S.
Martrenchard
, and
D.
Solgadi
,
J. Phys. Chem. A
105
,
5971
(
2001
).
21.
C. M.
Tseng
,
Y. T.
Lee
, and
C. K.
Ni
,
J. Chem. Phys.
121
,
2459
(
2004
).
22.
M. N. R.
Ashfold
,
B.
Cronin
,
A. L.
Devine
,
R. N.
Dixon
, and
M. G. D.
Nix
,
Science
312
,
1637
(
2006
).
23.
B.
Cronin
,
M. G. D.
Nix
,
R. H.
Qadiri
, and
M. N. R.
Ashfold
,
Phys. Chem. Chem. Phys.
6
,
5031
(
2004
).
24.
B.
Cronin
,
M. G. D.
Nix
,
A. L.
Devine
,
R. N.
Dixon
, and
M. N. R.
Ashfold
,
Phys. Chem. Chem. Phys.
8
,
599
(
2005
).
25.
C.
Ratzer
,
J.
Kupper
,
D.
Spangenberg
, and
M.
Schmitt
,
Chem. Phys.
283
,
153
(
2002
).
26.
D.
Proch
,
D. M.
Rider
, and
R. N.
Zare
,
Chem. Phys. Lett.
81
,
430
(
1981
).
27.
H. D.
Bist
,
J. C. D.
Brand
, and
D. R.
Williams
,
J. Mol. Spectrosc.
24
,
402
(
1967
);
H. D.
Bist
,
J. C. D.
Brand
, and
D. R.
Williams
,
J. Mol. Spectrosc.
24
,
413
(
1967
).
28.
M. G. D.
Nix
,
A. L.
Devine
,
B.
Cronin
, and
M. N. R.
Ashfold
,
Phys. Chem. Chem. Phys.
8
,
2610
(
2006
).
29.
S. H. S.
Wilson
,
J. D.
Howe
, and
M. N. R.
Ashfold
,
Mol. Phys.
88
,
841
(
1996
).
30.
P. A.
Cook
,
S. R.
Langford
,
R. N.
Dixon
, and
M. N. R.
Ashfold
,
J. Chem. Phys.
114
,
1672
(
2001
).
31.
K.-P.
Huber
and
G.
Herzberg
,
Constants of Diatomic Molecules
(
Van Nostrand Reinhold
,
New York
,
1979
).
32.
M. J.
Frisch
,
G. W.
Trucks
,
H. B.
Schlegel
 et al, GAUSSIAN 03, Revision B.04, Gaussian Inc, Pittsburgh, PA,
2003
.
33.
W.
Roth
,
P.
Imhof
,
M.
Gerhards
,
S.
Schumm
, and
K.
Kleinermanns
,
Chem. Phys.
252
,
247
(
2000
).
34.
E. B.
Wilson
,
Phys. Rev.
45
,
706
(
1934
).
35.
G.
Herzberg
,
Infrared and Raman Spectra of Polyatomic Molecules
(
Van Nostrand
,
Princeton, NJ
,
1945
).
36.
L. A.
Angel
and
K. M.
Ervin
,
J. Phys. Chem. A
108
,
8346
(
2004
).
37.
P.
Mulder
,
H. G.
Korth
,
D. A.
Pratt
,
G. A.
DiLabio
,
L.
Valgimigli
,
G. F.
Pedulli
, and
K. U.
Ingold
,
J. Phys. Chem. A
109
,
2647
(
2005
).
38.
J.
Lorentzon
,
P. A.
Malmqvist
,
M.
Fulscher
, and
B. O.
Roos
,
Theor. Chim. Acta
91
,
91
(
1995
).
39.
P. A.
Cook
,
S. R.
Langford
,
M. N. R.
Ashfold
, and
R. N.
Dixon
,
J. Chem. Phys.
113
,
994
(
2000
).
40.
R. N.
Zare
,
Angular Momentum: Understanding Spatial Aspects in Chemistry and Physics
(
Wiley
,
New York
,
1988
).
41.
Z. F.
Xu
and
M. C.
Lin
,
J. Phys. Chem. A
110
,
1672
(
2006
).
42.
D.
Spangenberg
,
P.
Imhof
, and
K.
Kleinermanns
,
Phys. Chem. Chem. Phys.
5
,
2505
(
2003
).
43.
D. H.
Mordaunt
,
R. N.
Dixon
, and
M. N. R.
Ashfold
,
J. Chem. Phys.
104
,
6472
(
1996
).
44.
C. P.
Schick
and
P. M.
Weber
,
J. Phys. Chem. A
105
,
3725
(
2001
).
45.
B.
Cronin
,
A. L.
Devine
,
M. G. D.
Nix
, and
M. N. R.
Ashfold
,
Phys. Chem. Chem. Phys.
8
,
3440
(
2006
).
46.
A.
Bussandri
and
H.
van Willigen
,
J. Phys. Chem. A
106
,
1524
(
2002
).
47.
J. G.
Radziszewski
,
M.
Gil
,
A.
Gorski
,
J.
Spanget-Larsen
,
J.
Waluk
, and
B. J.
Mroz
,
J. Chem. Phys.
115
,
9733
(
2001
).
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