Complex photodissociation dynamics of the weakly bound covalent NO dimer

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.

NO Dimer Geometry NO Dimer Molecular Orbitals

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 monomer.

The experiments in Hanna Reisler group at USC and Albert Stolow group in Canada probed excited state dynamics by ion and electron imaging techniques.

NO Dimer Excited State Experiment

Femtosecond experiments by Albert Stolow revealed different time scales for the (NO)2* dissapearance and NO(A) appearance.

NO Dimer Time-Resolved Photoelectron Spectrum

Time-resolved photoelectron spectrum, λpump = 210 nm, λprobe = 280 nm

Related Publications

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 (2006) Abstract  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 (2006) Abstract  PDF (532 kB)