In collaboration with several experimental and theoretical groups,
complex photodissociation dynamics of the NO dimer were uncovered.
(NO)2 is unstable at room temperature, but exists in cold
atmospheres and on cold surfaces, where it behaves differently than
the NO radical. It strongly absorbs UV radiation and falls apart.
The bonding in the dimer is intermediate between the covalent and
van der Waals, as evidenced by binding energy and the NN bondlength.
It derived from distributing two electrons in four nearly degenerate
orbitals made of the singly occupied π* orbitals of the NO
The experiments in Hanna Reisler group at USC
and Albert Stolow group in Canada
probed excited state dynamics by ion and electron imaging techniques.
Femtosecond experiments by Albert Stolow revealed different time
scales for the (NO)2* dissapearance and NO(A) appearance.
Time-resolved photoelectron spectrum, λpump = 210 nm, λprobe = 280 nm
47. S. V. Levchenko, H. Reisler, A. I. Krylov, O. Geßner, A. Stolow, H. Shi, and A. L. L. East
Photodissociation dynamics of the NO dimer: 1. Theoretical overview of the ultraviolet excited states
J. Chem. Phys. 125, 084301
PDF (656 kB)
46. O. Geßner, A. M. D. Lee, J. P. Shaffer, H. Reisler, S. V. Levchenko, A. I. Krylov, J. G. Underwood, H. Shi, A. L. L. East, D. M. Wardlaw, E. t.-H. Chrysostom, C. C. Hayden, and A. Stolow
Femtosecond multi-dimensional imaging of a molecular dissociation
Science 311, 219 – 222
PDF (532 kB)