1 and Ground Cationic states of p fluorotoluene Adrian Gardner William Tuttle Laura Whalley Andrew Claydon Joseph Carter and Timothy Wright International Symposium on Molecular Spectroscopy 19 ID: 627035
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Slide1
Torsional, Vibrational and Vibration-torsional Levels in the S1 and Ground Cationic states of p-fluorotoluene
Adrian Gardner, William Tuttle, Laura Whalley, Andrew Claydon, Joseph Carter and Timothy Wright
International Symposium on Molecular Spectroscopy, 19
th
-23
rd
June 2017Slide2
OverviewThis Talk:Introduction to molecules with a single methyl rotor (specifically
p-fluorotoluene,
p
FT
)aDiscussion of the torsional and vibration-torsion (vibtor) levels observed in the S1←S0 transitionTD09: Peter GronerDiscussion of the molecular symmetry group of p-xylene (pXyl)bTD10: Me again!Assignment of the low wavenumber range of S1←S0 electronic spectrum of pXylbFC05: Laura WhalleyTime resolved photoelectron experiments of high wavenumber vibrations of pFTcFC06: William TuttleExamines the similarities and differences in the S1←S0 electronic spectrum of pXyl and pFTd
a
A.M
. Gardner, W.D. Tuttle, L. Whalley, A. Claydon, J. H. Carter, T. G. Wright,
J. Chem. Phys.,
145,
124307 (2016)
b
A.M
. Gardner, W.D. Tuttle, P.
Groner
, T.G. Wright,
J. Chem. Phys.,
146
, 124308 (2017)
c
J
. A. Davies, L. E. Whalley, K. L. Reid,
PCCP
,
9
, 5051 (2017)
d
W.D
. Tuttle, A.M. Gardner, K.B. O’Regan, W.
Malewicz
, T.G. Wright,
J. Chem. Phys.,
146
124309 (2017) Slide3
Introduction
IVR rate increased by x40 [1]
[1] P. J. Timbers, C. S.
Parmenter
and D. B. Moss, J. Chem. Phys., 100, 1028 (1994).Slide4
Introduction
IVR rate increased by x40 [1]
[1] P. J. Timbers, C. S.
Parmenter
and D. B. Moss, J. Chem. Phys., 100, 1028 (1994).Slide5
Introduction
IVR rate increased by x40 [1]
[1] P. J. Timbers, C. S.
Parmenter
and D. B. Moss, J. Chem. Phys., 100, 1028 (1994).WavenumberaWavenumber12Slide6
Introduction
Tier model of IVR [2][2] D. J. Nesbitt and R. W. Field, J. Phys. Chem.,
100
, 12735 (1996).Slide7
Introduction
Tier model of IVR [2][2] D. J. Nesbitt and R. W. Field, J. Phys. Chem.,
100
, 12735 (1996).Could vibration-torsion levels be the doorway states we are looking for? Slide8
m
Free Rotor
0
±1
±2±3±4±5±6Energy / cm-1mHindered Rotor 0±1±23-±4±56-6+
3+
V
6
/2
V
6
/4
E =
m
2
FSlide9
Experimental Techniques
1 + 1 REMPI
1 + 1ʹ ZEKE-PFISlide10
Torsional Transitions
Below 100 cm
-1
the REMPI spectra look very similar.
These transitions are expected to be between “pure” torsional levels.Δm = 0 transition are expected to be the most intense (symmetry allowed), followed by Δm = ±3 transitions (torsion-electronic coupling), followed by Δm = ±6.Cannot cool between m = 1 and m = 0 levels in jet expansion.Form two torsional “ladders”: one involving m = 0, 3±, 6± … one involving m = ±1, ±2, ±4, ±5…for each electronic state.Slide11
Vibration-torsion Transitions
M
20
(b
1)[3] K. Okuyama, N. Mikami and M. Ito, J. Phys. Chem., 89, 5617 (1985).[4] A. Andrejeva et al., J. Mol. Spec., 321, 28 (2016)D20 (b1)D30 (b2)Slide12
a [201]c [301]b [m6(+)]S1←S0 REMPIZEKE via aZEKE via bZEKE
via
c
Torsion-vibration coupling
Wavenumber relative to
S
1
origin / cm
-1
[3]
K.
Okuyama
, N.
Mikami
and M. Ito,
J. Phys. Chem.
,
89
, 5617 (1985).
[5] V. L.
Ayles
et al
.,
J. Chem. Phys.
,
126
, 244304 (2007).Slide13
a [201]c [301]b [m6(+)]S1←S0 REMPIZEKE via aZEKE via bZEKE
via
c
m
6(+)
20
1
Torsion-vibration coupling
Calc.
Exp.
D
20
+
155
a
114
m
6+
185
186
D
30
+
317
a
221
Wavenumber relative to
S
1
origin / cm
-1
30
1
Based on previous assignments. [3,5]
[3]
K.
Okuyama
, N.
Mikami
and M. Ito,
J. Phys. Chem.
,
89
, 5617 (1985).
[5] V. L.
Ayles
et al
.,
J. Chem. Phys.
,
126
, 244304 (2007).
a
B3LYP/
aVTZ
(scaled 0.97)Slide14
M
20 (b1
)
[3]
K. Okuyama, N. Mikami and M. Ito, J. Phys. Chem., 89, 5617 (1985).[6] J. R. Gascooke, E. A. Virgo and W. D. Lawrance, J. Chem. Phys., 143, 044313, (2015).D20 (b1)Torsion-vibration coupling m6(+)Slide15
a [201m3(-)]c [202]b [m6(+)]S1←S0 REMPIZEKE via aZEKE via b
ZEKE
via
c
m
6(+)
Torsion-vibration coupling
Wavenumber relative to
S
1
origin / cm
-1
[3]
K.
Okuyama
, N.
Mikami
and M. Ito,
J. Phys. Chem.
,
89
, 5617 (1985).
a
B3LYP/
aVTZ
(scaled 0.97)
D
20
1
Calc.
Exp.
D
20
+
113
a
114
m
6+
185
186
(
m
3-
)
D
20
D
20
2
D
20
1
(
m
3-
)Slide16
b [m6(+)]S1←S0 REMPIZEKE via aZEKE via bZEKE via cTorsion-vibration coupling
Wavenumber relative to
S
1
origin / cm
-1
[3]
K.
Okuyama
, N.
Mikami
and M. Ito,
J. Phys. Chem.
,
89
, 5617 (1985).
D
20
1
(
m
3-
)
D
20
2
D
20
1
(
m
3-
)
m
6+
a [20
1
m
3(-)
]
c [20
2
]
D
20
m=
3(-)
,
m=
6(+)
and
2
D
20
levels
are all of the same symmetry so why do we see all of them
via
c
, but only two
via
a
and
b
?
and b part of
?Slide17
b [m6(+)]S1←S0 REMPIZEKE via aZEKE via bZEKE via cTorsion-vibration coupling
Wavenumber relative to
S
1
origin / cm
-1
[3]
K.
Okuyama
, N.
Mikami
and M. Ito,
J. Phys. Chem.
,
89
, 5617 (1985).
D
20
1
(
m
3-
)
D
20
2
D
20
1
(
m
3-
)
D
20
m=
3(-)
,
m=
6(+)
and
2
D
20
levels
are all of the same symmetry so why do we see all of them
via
c
, but only two
via
a
and
b
?
and b part of
a
and
b
are levels from different torsional ladders so
m=
6(+) is not a likely assignment for
b
.
?
m
6+
a [20
1
m
3(-)
]
c [20
2
]Slide18
Torsion-vibration coupling
a
D
20
(m=3-)(m=3-)D20(m=0)D20(m=3-)D202(m=0)bcD202D202
S
1
D
0
+
D
0
+
S
1
D
20
(
m
=4)
(
m
=4)
D
20
(
m
=1)
D
20
(
m
=4)
D
20
2
(
m
=1)
S
1
b
c
a
a
b
c
Wavenumber relative to
S
1
origin / cm
-1
D
20
(
m
=3-)
D
20
(
m
=4)
D
20
2
D
20
1
Transition involving levels with
m
= 0, 3, 6…
Transition involving levels with
m
= 1, 2, 4, 5…Slide19
[3]
K.
Okuyama
, N. Mikami and M. Ito, J. Phys. Chem., 89, 5617 (1985).[6] J. R. Gascooke, E. A. Virgo and W. D. Lawrance, J. Chem. Phys., 143, 044313, (2015).Torsion-vibration couplingSlide20
[3]
K.
Okuyama
, N. Mikami and M. Ito, J. Phys. Chem., 89, 5617 (1985).[6] J. R. Gascooke, E. A. Virgo and W. D. Lawrance, J. Chem. Phys., 143, 044313, (2015).Torsion-vibration couplingSlide21
Exp.No V-T interactionV-T interaction
D20m = 3(-) level “pushed down” while m = 6(-) pushed up.
ZEKE spectra
via
the 2D20 level shows transitions to torsional levels of both a and e symmetries.Torsion-vibration couplingSlide22
Exp.
No V-T interactionV-T interactionThe
D
20
m = 2 and m = 5 levels are both of eʹʹ symmetry and their ZOS wavenumbers are almost coincidental.This leads to a strong interaction, with the resulting eigenstates almost equal mixtures of the two ZOSs.Torsion-vibration couplingSlide23
ConclusionsZEKE spectra have been recorded via
several intermediate levels of the S1 electronic state of
p
FT
.Several bands previously assigned to “pure” vibrations, have been reassigned.Even in this (very) low wavenumber region assignments are not easy to make! Slide24
ConclusionsZEKE spectra have been recorded via
several intermediate levels of the S1 electronic state of
p
FT
.Several bands previously assigned to “pure” vibrations, have been reassigned.Even in this (very) low wavenumber region assignments are not easy to make! Unravelling the couplings between torsional, vibrational and vibtor levels is important to understand the spectroscopy of molecules with low wavenumber degrees of freedom.The low wavenumber levels discussed in this work will likely be observed in combination with higher wavenumber vibrations, further complicating the IVR dynamics at higher wavenumber.Slide25
ConclusionsZEKE spectra have been recorded via
several intermediate levels of the S1 electronic state of
p
FT
.Several bands previously assigned to “pure” vibrations, have been reassigned.Even in this (very) low wavenumber region assignments are not easy to make! Unravelling the couplings between torsional, vibrational and vibtor levels is important to understand the spectroscopy of molecules with low wavenumber degrees of freedom.The low wavenumber levels discussed in this work will likely be observed in combination with higher wavenumber vibrations, further complicating the IVR dynamics at higher wavenumber.Ongoing/Future WorkInvestigate higher wavenumber ranges in which couplings are expected to be more complicated and IVR rates faster. [SEE TALKS, FC05: Laura Whalley and FC06: William Tuttle]Investigate the effects of solvation on the coupling between vibrations, torsions and vibtor levels.Slide26
AcknowledgementsProf. Timothy Wright
William TuttleLaura Whalley
Andrew Claydon
Joseph Carter
Prof. Warren LawranceDr. Jason GascookeProf. Katharine ReidDr. Julia Davies This work has been supported by:Grant no. L021366/1