Physics

Guiding a Rupture

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Science  18 Sep 2009:
Vol. 325, Issue 5947, pp. 1477
DOI: 10.1126/science.325_1477b

Chemical transformations often involve two coupled stages of motion—electronic rearrangements within fractions of a trillionth of a second, followed by nuclear motion on a time scale one or more orders of magnitude longer. Over the past several decades, advances in laser technology have introduced pulses compressed sufficiently in time to glimpse these ultrafast dynamics, and in some cases to manipulate nuclear vibrational motion. A more recent goal is to achieve active control over electronic motion, by shaping even shorter pulses to map out the potential energy landscape and select particular pathways for the electrons to follow. The development of attosecond optics, using strong-field laser pulses of just a few optical cycles, with a controlled phase relationship between pulses, opens up the ability to pursue such designer reaction pathways. Experiments to date, however, have tended to probe the dynamics of rather simple, single-electron systems. Now, Znakovskaya et al. extend the principle of steering electrons with attosecond pulses to a more complex, multielectron system. They show that they can control the direction and energy of C+ and O+ fragments during the dissociative ionization of carbon monoxide molecules. Accompanying theoretical calculations explore the interplay of electronic excitations underlying the observations.

Phys. Rev. Lett. 103, 103002 (2009).

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