We study how the combination of long and short laser pulses can be used to induce torsion in an axially chiral biphenyl derivative (3,5-difluoro-3,5-dibromo-4-cyanobiphenyl). A long, with respect to the molecular rotational periods, elliptically polarized laser pulse produces 3D alignment of the molecules, and a linearly polarized short pulse initiates torsion about the stereogenic axis. The torsional motion is monitored in real-time by measuring the dihedral angle using femtosecond time-resolved Coulomb explosion imaging. Within the first 4 picoseconds (ps), torsion occurs with a period of 1.25 ps and an amplitude of 3° in excellent agreement with theoretical calculations. At larger times, the quantum states of the molecules describing the torsional motion dephase and an almost isotropic distribution of the dihedral angle is measured. We demonstrate an original application of covariance analysis of two-dimensional ion images to reveal strong correlations between specific ejected ionic fragments from Coulomb explosion. This technique strengthens our interpretation of the experimental data.

1.
2.
J.
Shao
and
P.
Hänggi
,
J. Chem. Phys.
107
,
9935
(
1997
).
3.
Y.
Fujimura
,
L.
González
,
K.
Hoki
,
J.
Manz
, and
Y.
Ohtsuki
,
Chem. Phys. Lett.
306
,
1
(
1999
).
4.
D.
Gerbasi
,
M.
Shapiro
, and
P.
Brumer
,
J. Chem. Phys.
115
,
5349
(
2001
).
5.
P.
Král
and
M.
Shapiro
,
Phys. Rev. Lett.
87
,
183002
(
2001
).
6.
K.
Hoki
,
L.
González
, and
Y.
Fujimura
,
J. Chem. Phys.
116
,
2433
(
2002
).
7.
D.
Kröner
,
M. F.
Shibl
, and
L.
González
,
Chem. Phys. Lett.
372
,
242
(
2003
).
8.
D.
Kröner
and
B.
Klaumünzer
,
Chem. Phys.
338
,
268
(
2007
).
9.
E. L.
Eliel
and
A. H.
Wilen
,
in Stereochemistry of Organic Compounds
(
Wiley
,
New York
,
1994
), Chap. 14.
10.
M.
Shapiro
and
P.
Brumer
,
J. Chem. Phys.
95
,
8658
(
1991
).
11.
S.
Ramakrishna
and
T.
Seideman
,
Phys. Rev. Lett.
99
,
103001
(
2007
).
12.
L. H.
Coudert
,
L. F.
Pacios
, and
J.
Ortigoso
,
Phys. Rev. Lett.
107
,
113004
(
2011
).
13.
S. M.
Parker
,
M. A.
Ratner
, and
T.
Seideman
,
J. Chem. Phys.
135
,
224301
(
2011
).
14.
C. B.
Madsen
,
L. B.
Madsen
,
S. S.
Viftrup
,
M. P.
Johansson
,
T. B.
Poulsen
,
L.
Holmegaard
,
V.
Kumarappan
,
K. A.
Jørgensen
, and
H.
Stapelfeldt
,
Phys. Rev. Lett.
102
,
073007
(
2009
).
15.
C. B.
Madsen
,
L. B.
Madsen
,
S. S.
Viftrup
,
M. P.
Johansson
,
T. B.
Poulsen
,
L.
Holmegaard
,
V.
Kumarappan
,
K. A.
Jørgensen
, and
H.
Stapelfeldt
,
J. Chem. Phys.
130
,
234310
(
2009
).
16.
J. J.
Larsen
,
K.
Hald
,
N.
Bjerre
,
H.
Stapelfeldt
, and
T.
Seideman
,
Phys. Rev. Lett.
85
,
2470
(
2000
).
17.
I.
Nevo
,
L.
Holmegaard
,
J. H.
Nielsen
,
J. L.
Hansen
,
H.
Stapelfeldt
,
F.
Filsinger
,
G.
Meijer
, and
J.
Küpper
,
Phys. Chem. Chem. Phys.
11
,
9912
(
2009
).
18.
Dipole moments and polarizabilities were computed with TURBOMOLE 6.2 (Ref. 35) at density functional theory (DFT) level, employing the B3LYP functional which combines Becke's three-parameter hybrid exchange functional36 with the Lee-Yang-Parr correlation functional;37 the correlation of the uniform electron gas was modeled with the Vosko-Wilk-Nusair VWN5 formulation.38 The doubly-polarized triple-zeta basis set, TZVPP,39 was used throughout. This level of theory has been shown to be suitable for the study of biphenyls.40 
19.
L.
Holmegaard
,
J. H.
Nielsen
,
I.
Nevo
,
H.
Stapelfeldt
,
F.
Filsinger
,
J.
Küpper
, and
G.
Meijer
,
Phys. Rev. Lett.
102
,
023001
(
2009
).
20.
F.
Filsinger
,
J.
Küpper
,
G.
Meijer
,
L.
Holmegaard
,
J. H.
Nielsen
,
I.
Nevo
,
J. L.
Hansen
, and
H.
Stapelfeldt
,
J. Chem. Phys.
131
,
064309
(
2009
).
21.
J. L.
Hansen
,
L.
Holmegaard
,
L.
Kalhøj
,
S. L.
Kragh
,
H.
Stapelfeldt
,
F.
Filsinger
,
G.
Meijer
,
J.
Küpper
,
D.
Dimitrovski
,
M.
Abu-samha
,
C. P. J.
Martiny
, and
L. B.
Madsen
,
Phys. Rev. A
83
,
023406
(
2011
).
22.
The spotsizes were determined by scanning a 10 μm pinhole across the foci of the laser beams. All peak intensities quoted in the text are calculated using the following formula
$I_0 = \frac{4\sqrt{\ln {2}}}{\pi ^{3/2}}\frac{E_{\mbox{pulse}}}{\omega ^2_0 \tau }$
I0=4ln2π3/2Epulseω02τ
, where ω0 is the spot size measured from the center of the profile till the position where the the intensity has dropped to I0/e, and τ is the pulse duration measured at FWHM.
23.
The dynamic polarizabilities of the molecule, at equilibrium, λ = 800 nm are αzz = 46.83 Å3, αyy = 16.82 Å3, αxx = 32.02 Å3.
24.
H.
Stapelfeldt
and
T.
Seideman
,
Rev. Mod. Phys.
75
,
543
(
2003
)..
25.
J. L.
Hansen
,
H.
Stapelfeldt
,
D.
Dimitrovski
,
M.
Abu-samha
,
C. P. J.
Martiny
, and
L. B.
Madsen
,
Phys. Rev. Lett.
106
,
073001
(
2011
).
26.
L. J.
Frasinski
,
K.
Codling
, and
P. A.
Hatherly
,
Science
246
,
1029
(
1989
).
27.
J. W.
Goodman
, in
Statistical Optics
(
Wiley
,
New York
,
1985
).
28.
R.
Dörner
,
V.
Mergel
,
O.
Jagutzki
,
L.
Spielberger
,
J.
Ullrich
,
R.
Moshammer
, and
H.
Schmidt-Böcking
,
Phys. Rep.
330
,
95
(
2000
).
29.
J.
Ullrich
,
R.
Moshammer
,
A.
Dorn
,
R.
Dörner
,
L.
Schmidt
, and
H.
Schmidt-Böcking
,
Rep. Prog. Phys.
66
,
1463
(
2003
).
30.
R. H.
Brown
and
R. Q.
Twiss
,
Nature (London)
178
,
1046
(
1956
).
31.
W. P.
Aue
,
E.
Bartholdi
, and
R. R.
Ernst
,
J. Chem. Phys.
64
,
2229
(
1976
).
32.
C.
Schröter
,
K.
Kosma
, and
T.
Schultz
,
Science
333
,
1011
(
2011
).
33.
D.
Korolev
and
N.
Bumagin
,
Tetrahedron Lett.
46
,
5751
(
2005
).
34.
T.
Itoh
,
Y.
Nakata
,
K.
Hirai
, and
H.
Tomioka
,
J. Am. Chem. Soc.
128
,
957
(
2006
).
35.
R.
Ahlrichs
,
M.
Bär
,
M.
Häser
,
H.
Horn
, and
C.
Kölmel
,
Chem. Phys. Lett.
162
,
165
(
1989
).
36.
A. D.
Becke
,
J. Chem. Phys.
98
,
5648
(
1993
).
37.
C.
Lee
,
W.
Yang
, and
R. G.
Parr
,
Phys. Rev. B
37
,
785
(
1988
).
38.
S. H.
Vosko
,
L.
Wilk
, and
M.
Nusair
,
Can. J. Phys.
58
,
1200
(
1980
).
39.
A.
Schäfer
,
C.
Huber
, and
R.
Ahlrichs
,
J. Chem. Phys.
100
,
5829
(
1994
).
40.
M. P.
Johansson
and
J.
Olsen
,
J. Chem. Theory Comput.
4
,
1460
(
2008
).
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