Photoelectron spectra are reported for one-photon resonant, two-photon ionization of jet-cooled diacetylene via a number of vibronic levels of the 1 1Δu state. An improved value for the adiabatic ionization threshold is found to be 82 064±30 cm−1 (10.175±0.004 eV), in good agreement with the earlier result. The photoelectron spectra of different vibronic bands of the 1 1Δu state nearly all show long progressions in what appear to be low frequency bending vibrations. At energies just above the ionization threshold, the observed progressions can be understood in terms of excitation of a single Renner-Teller active mode in the ion, with Renner-Teller parameters similar to those of the ν4+trans-bending mode in the ground state acetylene cation.

1.
T. S.
Zwier
and
M.
Allen
,
Icarus
123
,
578
(
1996
).
2.
R. E.
Bandy
,
C.
Lakshminarayan
, and
T. S.
Zwier
,
J. Phys. Chem.
96
,
5337
(
1992
).
3.
R. E.
Bandy
,
C.
Lakshminarayan
,
R. K.
Frost
, and
T. S.
Zwier
,
J. Chem. Phys.
98
,
5362
(
1993
).
4.
R. K.
Frost
,
C. A.
Arrington
,
C.
Ramos
, and
T. S.
Zwier
,
J. Am. Chem. Soc.
118
,
4451
(
1996
).
5.
C. A.
Arrington
,
C.
Ramos
,
A. D.
Robinson
, and
T. S.
Zwier
,
J. Phys. Chem. A
102
,
3315
(
1998
).
6.
C. A.
Arrington
,
C.
Ramos
,
A. D.
Robinson
, and
T. S.
Zwier
,
J. Phys. Chem. A
103
,
1294
(
1999
).
7.
F.
Vila
,
P.
Borowski
, and
K. D.
Jordan
,
J. Phys. Chem. A
104
,
9009
(
2000
).
8.
A.
Karpfen
and
H.
Lischka
,
Chem. Phys.
102
,
91
(
1986
).
9.
S. C.
Woo
and
T. C.
Chu
,
J. Chem. Phys.
3
,
541
(
1935
).
10.
S. C.
Woo
and
T. C.
Chu
,
J. Chem. Phys.
5
,
786
(
1937
).
11.
H. J.
Haink
and
M.
Jungen
,
Chem. Phys. Lett.
61
,
319
(
1979
).
12.
K. W.
Chang
and
W. R.
Graham
,
J. Mol. Spectrosc.
94
,
69
(
1982
).
13.
C.
Baker
and
D. W.
Turner
,
Chem. Commun. (London)
1967
,
797
.
14.
W. L.
Smith
,
Proc. R. Soc. London, Ser. A
300
,
519
(
1967
).
15.
P.
Kruit
and
F. H.
Read
,
J. Phys. E
16
,
313
(
1983
).
16.
W. L.
Glab
,
P. M.
Dehmer
, and
J. L.
Dehmer
,
J. Chem. Phys.
104
,
4937
(
1996
).
17.
J. H.
Calloman
,
Can. J. Phys.
34
,
1046
(
1956
).
18.
M.
Allan
,
E.
Kloster-Jensen
, and
J. P.
Maier
,
Chem. Phys.
7
,
11
(
1976
).
19.
W. C.
Price
and
A. D.
Walsh
,
Trans. Faraday Soc.
41
,
381
(
1945
).
20.
G. Herzberg, Molecular Spectra and Molecular Structure, III (Van Nostrand Reinhold, New York, 1966).
21.
S. T.
Pratt
,
P. M.
Dehmer
, and
J. L.
Dehmer
,
J. Chem. Phys.
95
,
6238
(
1991
).
22.
S. T.
Pratt
,
P. M.
Dehmer
, and
J. L.
Dehmer
,
J. Chem. Phys.
99
,
6233
(
1993
).
23.
Y. F.
Zhu
,
R.
Shehadah
, and
E. R.
Grant
,
J. Chem. Phys.
99
,
5723
(
1993
).
This paper assigned Renner-Teller structure in a nonpenetrating Rydberg state of acetylene and found similar parameters to those observed in the ion. However, the Rydberg bands were later reassigned to a different state without invoking the Renner-Teller effect. See,
J. H.
Fillion
,
A.
Campos
,
J.
Pedersen
,
N.
Shafizadeh
, and
D.
Gauyacq
,
J. Chem. Phys.
105
,
22
(
1996
).
24.
R. N.
Dixon
,
G.
Duxbury
,
M.
Horani
, and
J.
Rostas
,
Mol. Phys.
22
,
977
(
1971
).
25.
K. K. Lehmann, P. R. Winter, and T. S. Zwier (to be published).
26.
F.
Duschinsky
,
Acta Physicochim. URSS
7
,
551
(
1937
).
27.
E. V.
Doktorov
,
I. A.
Malhin
, and
V. I.
Man’ko
,
J. Mol. Spectrosc.
64
,
302
(
1977
).
28.
T. E.
Sharp
and
H. M.
Rosenstock
,
J. Chem. Phys.
4
,
3453
(
1964
).
29.
The calculated change in the C≡C bond length between the Δu1 state of the neutral and the Πg2 state of the cation at the CAS/6-31G**5d level of theory is Δr=0.0283 Å. This was adjusted to Δr=0.0183 Å in order to obtain the Franck–Condon profile in Fig. 7(b).
30.
J. L.
Hardwick
and
D. A.
Ramsay
,
Chem. Phys. Lett.
48
,
399
(
1977
).
31.
K.
Müller-Dethlefs
and
E. W.
Schlag
,
Annu. Rev. Phys. Chem.
42
,
109
(
1991
).
32.
E. W. Schlag, ZEKE Spectroscopy (Cambridge University Press, Cambridge, 1998).
This content is only available via PDF.
You do not currently have access to this content.