The two‐color laser‐induced grating (TC‐LIG) technique has been employed to probe the predissociative Rydberg states (4pσ) M2Σ+ (v=1) and (3dσ,π) H2Σ+, H′ 2Π± (v=2) and the non‐Rydberg B2Π (v=26) state of nitric oxide. The ultraviolet pump laser frequency is fixed to a specific rotational line of the A2Σ+ (v′=1 and 2)←X2Π3/2 (v″=0) transition of NO. Interference of two pump laser beams crossing at a small angle in the gas sample forms a population grating. Then, the visible probe laser beam is diffracted off the grating as the signal beam when the probe laser frequency is resonant to a transition from the rotational level excited by the pump laser. Term values and rotational assignments of the H2Σ+, H′ 2Π± (v=2)–B2Π3/2 (v=26) states have been established for the first time, resulting in the value of ∼1.77 cm−1 for the l‐uncoupling constant. Line broadenings due to predissociation are observed in the TC‐LIG spectra for the M2Σ+ (v=1) and H2Σ+, H′ 2Π+ (v=2) states. The linewidths of the M2Σ+ (v=1) state show no marked rotational dependence except for the N=4 level which is locally perturbed. On the other hand, the predissociative lifetimes of the H2Σ+ and H′ 2Π+ (v=2) states exhibit a significant rotational dependence: The linewidth of the former state decreases with N, while the reverse tendency is seen for the latter. The mixing between the H2Σ+ and H′ 2Π+ states caused by l‐uncoupling explains the observed rotational dependence successfully.

1.
H. J. Eichler, P. Günter, and D. W. Pohl, Laser-Induced Dynamic Gratings (Springer, Berlin, 1986).
2.
M. A.
Buntine
,
D. W.
Chandler
, and
C. C.
Hayden
,
J. Chem. Phys.
97
,
707
(
1992
).
3.
T. J.
Butenhoff
and
E. A.
Rohlfing
,
J. Chem. Phys.
98
,
5460
(
1993
).
4.
E. F.
McCormack
,
S. T.
Pratt
,
P. M.
Dehmer
, and
J. L.
Dehmer
,
Chem. Phys. Lett.
211
,
147
(
1993
).
5.
A.
Lagerqvist
and
E.
Miescher
,
Can. J. Phys.
44
,
1525
(
1966
).
6.
K. P.
Huber
and
E.
Miescher
,
Helv. Phys. Acta
36
,
257
(
1963
).
7.
E.
Miescher
,
Can. J. Phys.
49
,
2350
(
1971
).
8.
C.
Amiot
,
Chem. Phys. Lett.
83
,
40
(
1981
).
9.
M.
Huber
,
Helv. Phys. Acta
37
,
329
(
1964
).
10.
E. Miescher and K. P. Huber, Spectroscopy, edited by D. A. Ramsay, M.T.P. International Review of Science, Physical Chemistry Series 2 (Butterworths, London, 1976), Vol. 3, pp. 37–73.
11.
W. L.
Glab
and
J. P.
Hessler
,
Appl. Opt.
26
,
3181
(
1987
).
12.
R. J.
Miller
,
L.
Li
,
Y.
Wang
,
W. A.
Chupka
, and
S. D.
Colson
,
J. Chem. Phys.
90
,
754
(
1989
).
13.
J. A.
Gray
,
J. E. M.
Goldsmith
, and
R.
Trebino
,
Opt. Lett.
18
,
444
(
1993
).
14.
S.
Williams
,
J. D.
Tobiason
,
J. R.
Dunlop
, and
E. A.
Rohlfing
,
J. Chem. Phys.
102
,
8342
(
1995
).
The theoretical approach employs diagrammatic perturbation theory in an extension of a recent treatment of degenerate four-wave mixing [
S.
Williams
,
R. N.
Zare
, and
L. A.
Rahn
,
J. Chem. Phys.
101
,
1072
(
1994
)].
15.
S. N.
Dobryakov
and
Ya. S.
Lebedev
,
Sov. Phys. Dokl.
13
,
873
(
1969
).
16.
C.
Amiot
and
J.
Verges
,
Phys. Scr.
26
,
422
(
1982
).
17.
G. Herzberg, Spectra of Diatomic Molecules (Van Nostrand Reinhold, New York, 1950), p. 247.
18.
C.
Jungen
,
J. Chem. Phys.
53
,
4168
(
1970
).
19.
R.
Gallusser
and
K.
Dressler
,
J. Chem. Phys.
76
,
4311
(
1982
).
20.
K.
Dressler
and
E.
Miescher
,
J. Chem. Phys.
75
,
4310
(
1981
).The vibrational numbering of the L2Πi state employed in this reference differs from that in Ref. 19 by one quantum. The authors adopt the numbering given in Ref. 19 in the present paper.
21.
E.
Miescher
,
J. Mol. Spectrosc.
69
,
281
(
1978
).
22.
J. A.
Guest
and
L. C.
Lee
,
J. Phys. B
14
,
3401
(
1981
).
23.
A.
Lagerqvist
and
E.
Miescher
,
Helv. Phys. Acta
31
,
221
(
1958
).
24.
T.
Ebata
,
N.
Mikami
, and
M.
Ito
,
J. Chem. Phys.
78
,
1132
(
1983
).
25.
W. Y.
Cheung
,
W. A.
Chupka
,
S. D.
Colson
,
D.
Gauyacq
,
P.
Avouris
, and
J.
Wynne
,
J. Phys. Chem.
90
,
1086
(
1986
).
26.
M. N. R.
Ashfold
,
R. N.
Dixon
,
J. D.
Prince
,
B.
Tutcher
, and
C. M.
Western
,
J. Chem. Soc., Faraday Trans. 2
82
,
1257
(
1986
).
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