The high-order harmonic generation (HHG) of coherent light pulses in gases is strictly dependent on the ionization dynamics that delocalizes the electron wave function in the laser field continuum. Here we report on the investigation of such dynamics by varying the energy of a 400 nm, 60 fs driving laser pulse. The experimental data provide the unambiguous evidence of a hybrid dynamical region, not described by the full-tunneling approximation models, where the HHG photon number exponentially decays when the Keldysh parameter is varied from 1 to 3. Finally, a phenomenological model, suitable to account for this hybrid regime, is reported.

1.
T.
Pfeifer
,
C.
Spielman
, and
G.
Gerber
,
Rep. Prog. Phys.
69
,
443
(
2006
).
2.
T.
Brabec
and
F.
Krausz
,
Rev. Mod. Phys.
72
,
545
(
2000
).
3.
P.
Jaegle
,
Coherent Sources of XUV Radiation
(
Springer
,
Berlin
,
2006
).
4.
M.
Uiberacker
,
Th.
Uphues
,
M.
Schultze
,
A. J.
Verhoef
,
V.
Yakovlev
,
M. F.
Kling
,
J.
Rauschenberger
,
N. M.
Kabachnik
,
H.
Schoeder
,
M.
Lezius
,
K. L.
Kompa
,
H. -G.
Muller
,
M. J. J.
Vrakking
,
S.
Hendel
,
U.
Kleineberg
,
U.
Heinzman
,
M.
Drescher
, and
F.
Krausz
,
Nature (London)
446
,
627
(
2007
).
5.
A. L.
Cavalieri
,
N.
Mueller
,
Th.
Uphues
,
V. S.
Yakovlev
,
A.
Baltuska
,
B.
Horvath
,
B.
Schmidt
,
L.
Bluemel
,
R.
Holzwarth
,
S.
Hendel
,
M.
Drescher
,
U.
Kleineberg
,
P. M.
Echenique
,
R.
Kienberg
,
F.
Krausz
, and
U.
Heinzman
,
Nature (London)
449
,
1029
(
2007
).
6.
P. B.
Corkum
and
F.
Krausz
,
Nat. Phys.
3
,
381
(
2007
).
7.
E.
Goulielmakis
,
M.
Schultze
,
M.
Hofstetter
,
V. S.
Yakovlev
,
J.
Gagnon
,
M.
Uiberacker
,
A. L.
Aquila
,
E. M.
Gullikson
,
D. T.
Attwood
,
R.
Kienberger
,
F.
Krausz
, and
U.
Kleineberg
,
Science
320
,
1614
(
2008
).
8.
A. S.
Sandhu
,
E.
Gagnon
,
R.
Santra
,
V.
Sharma
,
W.
Li
,
P.
Ho
,
P.
Ranitovic
,
C. L.
Cocke
,
M. M.
Murname
, and
H.
Kapteyn
,
Science
322
,
1081
(
2008
).
9.
S.
Mathias
,
L.
Miaja-Avila
,
M.
Murname
,
H.
Kapteyn
,
M.
Aeschlimann
, and
M.
Bauer
,
Rev. Sci. Instrum.
78
,
083105
(
2007
).
10.
C.
Lynga
,
A.
L’Huillier
, and
C. -G.
Wahlstroem
,
J. Phys. B
29
,
3293
(
1996
).
11.
M.
Lewenstein
,
Ph.
Balcou
,
M. Yu.
Ivanov
,
A.
L’Huillier
, and
P. B.
Corkum
,
Phys. Rev. A
49
,
2117
(
1994
).
12.
M. V.
Ammosov
,
N. B.
Delone
, and
V. P.
Keoinov
,
Zh. Eksp. Teor. Fiz.
91
,
2008
(
1986
)
M. V.
Ammosov
,
N. B.
Delone
, and
V. P.
Keoinov
, [
Sov. Phys. JETP
64
,
1191
(
1987
)].
13.
G. L.
Yudin
and
M. Y.
Ivanov
,
Phys. Rev. A
64
,
013409
(
2001
).
14.
15.
A.
Gordon
and
F.
Kaertner
,
Opt. Express
13
,
2941
(
2005
).
16.
D. L.
Bondar
,
Phys. Rev. A
78
,
015405
(
2008
).
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