Supplemental material
for
“Ultrafast Excited State Dynamics of Spirilloxanthin in Solution and Bound to Core
Antenna Complexes: Identification of the S* and T1 States”
Daisuke Kosumia,b*, Satoshi Marutaa,b, Tomoko Horibea,b, Yuya Nagaokaa,
Ritsuko Fujiib,c, Mitsuru Sugisakia,b,c, Richard J. Cogdelld, and Hideki Hashimotoa,b,c*
a
The Osaka City University Advanced Research Institute for Natural Science and Technology
(OCARINA), 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka, 558-8585 Japan
b
c
d
JST/CREST, 4-1-8 Hon-chou, Kawaguchi, Saitama, 332-0012 Japan
Department of Physics, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto,
Sumiyoshi-ku, Osaka, 558-8585 Japan
Glasgow Biomedical Research Centre, University of Glasgow, 126 University Place, Glasgow, G12
8QQ, Scotland, UK
* Corresponding authors: Tel +81-6-6605-2529, e-mail kosumi@sci.osaka-cu.ac.jp (D.Kosumi), Tel
+81-6-6605-3627, e-mail hassy@sci.osaka-cu.ac.jp (H. Hashimoto)
Estimation of the number of photons absorbed by the S2 state of spirilloxanthin under the
excitation condition at 2.07 eV.
When chromatophores from Rhodospirillum (Rsp.) rubrum S1 are excited at 2.07 eV, the
excitation pulse is resonant to the red edge of the Qx band of bacteriochlorophyll (Bchl) a, as shown
in Fig. 1. Additionally, the S2 state of spirilloxanthin (Spx) can be also excited. Here, we estimate
the number of photons absorbed by the S2 state under the excitation condition at 2.07 eV.
The absorption spectrum of S2 of Spx bound to the protein complex can be extracted by
subtraction of the steady-state absorption spectrum of Rsp. rubrum G9 (carotenoidless mutant) from
Rsp. rubrum S1. The subtracted absorption spectrum of Spx. is shown in Fig. S1(a), well agreeing
with that of Spx in benzene shown in Fig.1. The spectra of the excitation pulse and steady-state
absorption of Spx slightly overlap. In order to estimate how many S2 and Qx absorb photons under
the excitation condition at 2.07 eV, we calculate an overlap integral between the excitation and the
absorption band of S2 or Qx. A value of an overlap integral between excitation pulse and absorption
band is proportional to the number of excited molecules.
First, we calculated the 0-0 band of S2 of Spx by the fit to the subtracted absorption spectrum
using a Gaussian function (the dash-dotted line in Fig. 1(b)). Next, we calculated the Qx band of
Bchl a by the same procedure. The Qx absorption region (1.95~2.20 eV) involves the red-edge of
the 0-0 band of S2 and the contribution from scattering (as chromatophores from Rsp. rubrum S1
(G9) are vesicles). We calculated the Qx band of Bchl a (the dashed and double-dotted line in Fig.
S1(b)) including these contributions. Finally, we calculated an overlap integral between the
excitation and the absorption bands of S2 and Qx. A relative value of overlap integral for Qx and S2
was determined to be 14.8, suggesting that direct excitation to S2 of Spx is essentially negligible.
Global analysis based on a combining model
Previous ultrafast spectroscopic study on an artificial light-harvesting complex demonstrated
that the excitation intensity dependence of S1 and S* can be explained by combining sequential
energy flow of S2→S1→S* (hot S0)→S0 and generation of S* (hot S0) by impulsive stimulated
Raman scattering (ISRS). Therefore, we analyze the obtained kinetics of Spx in benzene and
bound to core complexes using this combining model. Fig. S5 represents species-associated
difference spectra (SADS) of Spx in benzene and bound to core complexes based on a combining
mode. The SADS based on a combining model are identical with those using a sequential model,
suggesting that impulsive stimulated Raman process less contributed to the generation of S* in our
excitation condition (intensity of 5 nJ/pulse and pulse width of 80 fs).
Table S1: The obtained rise/decay time constants of Rsp. rubrum S1 and G9 after excitation into
the Qx band.
Rsp. rubrum G9
50 fs
Qx
700 fs
singlet annihilation
14 ps
hot Qy
180 ps
Qy
Rsp. rubrum S1
30 fs
Qx
250 fs
hot S1
1.4 ps
S1
5.8 ps
S*
> 400 ps
T1
180 ps
Qy
Figure S1
1000 800
1 (a) Q
y
Wavelength (nm)
600
400
Rsp. rubrum S1
Rsp. rubrum G9
Rsp. rubrum S1-G9
0.5
Absorbance/Intensity
Qx exc.
0
0.6
0.5
0.4
Soret
S2
Qx
2
3
Photon Energy (eV)
Rsp. rubrum S1
Rsp. rubrum S1-G9
fit to the 0-0 band of S2
fit to the Qx band
excitation
(b)
0.3
0.2
0.1
0
1.8
baseline
2
2.2
2.4
2.6
Photon Energy (eV)
2.8
Figure S1: (a) The steady-state absorption spectra of Rsp. rubrum S1 and G9 and the difference
absorption spectrum between Rsp. rubrum S1 and G9. The steady-state absorption spectra of Rsp.
rubrum S1 and G9 are normalized at their Soret bands. (b) Enlargement of the spectral region of
the Spx absorption.
Figure S2
Wavelength (nm)
600
Absorbance Change
700
Rsp. rubrum S1
(a)
0
1.0 ps
100 ps (x3)
0
1.6
6
5
Scaled A
500
1.8
2
2.2
2.4
Photon Energy (eV)
2.6
(b)
4
3
2
1
0
0
T1+S* (1.0 ps)
S1 (+S*) (1.0 ps)
S0 (1.0 ps)
T1 (100 ps)
20
40
60
80
100
Excitation Intensity (nJ/pulse)
Figure S2: (a) Photo-induced absorption spectra of Rsp. rubrum S1 taken at 1.0 and 100 ps after
excitation at 2.25 eV (excitation intensity was set to 5 nJ/pulse). (b) Excitation intensity
dependence of absorbance changes of Rsp. rubrum S1, given by excitation at 2.25 eV. The signals
were monitored at energies indicated by the arrows in the panel of (a).
Figure 3
(a) 0
0
2.45 eV
2.45 eV
Rsp. rubrum S1
Qx exc.
Absorbance Change
Absorbance Change
Rsp. rubrum S1
Qx exc.
2.19 eV
0
0
2.10 eV
2.19 eV
0
0
2.10 eV
2.00 eV
2.00 eV
0
0
0
1
(b)
2
3
Delay Time (ps)
4
5
0
Rsp. rubrum G9
Qx exc.
10
20
Delay Time (ps)
30
Rsp. rubrum G9
Qx exc.
2.45 eV
Absorbance Change
Absorbance Change
2.45 eV
0
2.19 eV
0
0
2.10 eV
0
2.19 eV
0
0
2.10 eV
2.00 eV
2.00 eV
0
0
0
1
2
3
Delay Time (ps)
4
5
0
10
20
Delay Time (ps)
30
Figure S3: Kinetic traces of photo-induced absorption signals of (a) Rsp. rubrum S1 and (b) Rsp.
rubrum G9 after excitation to the Qx band at 2.07 eV. Solid lines are the best fits.
Normalized Absorbance Change
Figure S4
Wavelength (nm)
600
700
(a)
0
500
Rsp. rubrum
S1
G9
1.0 ps
100 ps (x3)
0
1.6
4
1.8
2
2.2
2.4
Photon Energy (eV)
2.6
Scaled A
(b)
3
2
1
0
0
T1+S* (1.0 ps)
T1 (100 ps)
S1 (1.0 ps)
100
Excitation Intensity (nJ/pulse)
200
Figure S4: (a) Photo-induced absorption spectra of Rsp. rubrum S1 and G9 taken at 1.0 and 100 ps
after excitation to the Qx band of Bchl a at 2.07 eV (excitation intensity was set to 20 nJ/pulse). (b)
Excitation intensity dependence of absorbance changes of Rsp. rubrum S1, given by excitation at
2.07 eV. The signals were monitored at energies indicated by the arrows in the panel of (a).
Figure S5
700
Wavelength (nm)
600
in benzene
0.01
500
70 fs (S2)
300 fs (hot S1)
1.4 ps (S1)
5.8 ps (S*)
in protein complexes
Qx
hot S1
Qy
S1
0
Absorbance Change
S2
T1
-0.01
0.01
S*
Rsp. rubrum S1
Spx
Bchl
(sequential+ISRS)
0
-0.01
-0.02
1.6
40 fs (S2)
250 fs (hot S1)
1.4 ps (S1)
5.8 ps (S*)
1 ns (T1)
1.8
2
2.2
2.4
Photon Energy (eV)
2.6
Figure S5: Species-associated difference spectra of Spx in benzene and Rsp. rubrum S1 obtained by
the global fit based on a combining model (sequential and ISRS). Here, we assumed that S* is the
vibrational hot ground state. The kinetic models are also represented.
Figure S6
Wavelength (nm)
600
550
500
Normalized Absorbance Change
650
Spx in benzene
0
1.0 ps
10 ps
Rsp. rubrum S1
0
2
2.2
2.4
Photon Energy (eV)
2.6
Figure S6: A comparison of the bleaching signal of Spx in benzene and Rsp. rubrum S1 taken at
1.0 ps (solid lines) and 6.0 ps (dashed lines). The spectra are normalized at 2.43 eV for Spx in
benzene and at 2.42 eV for Rsp. rubrum S1.