DOI: 10.1126/science.1107291. Dark Structures in Molecular Radiationless Transitions Determined by Ultrafast Diffraction

Dark Structures in Molecular Radiationless Transitions Determined by Ultrafast Diffraction

10.1126/science.1107291

Crossref journal-article

American Association for the Advancement of Science (AAAS)

Science (221)

Abstract

The intermediate structures formed through radiationless transitions are termed “dark” because their existence is inferred indirectly from radiative transitions. We used ultrafast electron diffraction to directly determine these transient structures on both ground-state and excited-state potential energy surfaces of several aromatic molecules. The resolution in space and time (0.01 angstrom and 1 picosecond) enables differentiation between competing nonradiative pathways of bond breaking, vibronic coupling, and spin transition. For the systems reported here, the results reveal unexpected dynamical behavior. The observed ring opening of the structure depends on molecular substituents. This, together with the parallel bifurcation into physical and chemical channels, redefines structural dynamics of the energy landscape in radiationless processes.

Bibliography

Srinivasan, R., Feenstra, J. S., Park, S. T., Xu, S., & Zewail, A. H. (2005). Dark Structures in Molecular Radiationless Transitions Determined by Ultrafast Diffraction. Science, 307(5709), 558â563.

Authors 5

Ramesh Srinivasan (first)
Jonathan S. Feenstra (additional)
Sang Tae Park (additional)
Shoujun Xu (additional)
Ahmed H. Zewail (additional)

References 45 Referenced 137

E. C. Lim Ed. Molecular Luminescence (Benjamin New York 1969).
E. C. Lim, Adv. Photochem.23, 165 (1997). (10.1002/9780470133545.ch3) / Adv. Photochem. (1997)
J. D. Baldwin, in Reactive Intermediate Chemistry, R. A. Moss, M. S. Platz, M. Jones, Eds. (Wiley, New York, 2004), p. 899. / Reactive Intermediate Chemistry (2004)
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J. Michl, in Conical Intersections: Electronic Structure, Dynamics and Spectroscopy, W. Domcke, D. R. Yarkony, H. Koppel, Eds. (World Scientific, Singapore, 2004), p. ix. / Conical Intersections: Electronic Structure, Dynamics and Spectroscopy (2004)
10.1063/1.1703267
K. B. Eisenthal Ed. Applications of Picosecond Spectroscopy to Chemistry (Reidel Boston 1984). (10.1007/978-94-009-6427-3)
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10.1126/science.291.5503.458
R. Srinivasan, V. A. Lobastov, C.-Y. Ruan, A. H. Zewail, Helv. Chim. Acta86, 1763 (2003). / Helv. Chim. Acta (2003)
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Although it is conceivable that the hot ground-state molecules could undergo further ring-opening reaction our one-photon energy of ∼107 kcal/mol is inadequate for complete C–N bond scission on the ground state. Furthermore cleavage via this mechanism is known to proceed via initial loss of the α-hydrogen atom to form the pyridyl radical ( 44 ); however there is minimal loss of hydrogen observed in pyridine upon photoexcitation ( 23 ).
10.1063/1.438081
I. Yamazaki, K. Sushida, H. Baba, J. Lumin.18–9, 425 (1979). / J. Lumin. (1979)
10.1039/dc9837500395
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10.1021/j100316a019
A. V. Polevoi, V. M. Matyuk, G. A. Grigor'eva, V. K. Potatov, Khim. Vys. Energ.18, 195 (1984). / Khim. Vys. Energ. (1984)
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10.1021/jp000821q
Supported by NSF and the U.S. Air Force Office of Scientific Research.

Dates

Type	When
Created	20 years, 7 months ago (Jan. 6, 2005, 10:45 p.m.)
Deposited	1 year, 7 months ago (Jan. 9, 2024, 9:26 p.m.)
Indexed	2 days, 13 hours ago (Aug. 21, 2025, 12:38 p.m.)
Issued	20 years, 6 months ago (Jan. 28, 2005)
Published	20 years, 6 months ago (Jan. 28, 2005)
Published Print	20 years, 6 months ago (Jan. 28, 2005)

Funders 0

None

BibTeX

@article{Srinivasan_2005, title={Dark Structures in Molecular Radiationless Transitions Determined by Ultrafast Diffraction}, volume={307}, ISSN={1095-9203}, url={http://dx.doi.org/10.1126/science.1107291}, DOI={10.1126/science.1107291}, number={5709}, journal={Science}, publisher={American Association for the Advancement of Science (AAAS)}, author={Srinivasan, Ramesh and Feenstra, Jonathan S. and Park, Sang Tae and Xu, Shoujun and Zewail, Ahmed H.}, year={2005}, month=jan, pages={558–563} }

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