NO electrons leave different electronic channels with different delays
A peer-reviewed experiment measured relative electron-emission delays in nitric oxide using ultrashort light pulses. Different electronic states of the remaining ion had distinct delays, while differences between examined vibrational levels stayed within uncertainty. Scattering calculations reproduced the main energy trend. The findings test how a molecule’s electric potential affects an outgoing electron within the measured range.
Science··Midday
Light exposes a difference between electronic channels
Electrons released from nitric oxide, the molecule abbreviated NO, showed different relative delays depending on the electronic state of the ion left behind. The single peer-reviewed experiment combined extreme-ultraviolet pulses with a weak infrared probing field. It covered photon energies of 26–48 electronvolts, using interference between two-photon pathways to extract the timing difference. The measurement compared emission channels within the same molecule.[1]
A relative delay changes sign as energy increases
The b channel’s delay against the ground X channel changed from about 60 attoseconds in the lower-energy region to about minus 50 attoseconds as energy increased. These values describe a relative phase difference, rather than an absolute electron travel time. Scattering calculations broadly matched the energy trend. The researchers linked it to shape resonances, in which the molecular potential temporarily traps components of the outgoing electron wave.[1]
Vibrational differences stayed within uncertainty
The vibrational comparison concerned levels within the ground electronic state, in an energy region without a strong resonance. Any difference between these levels was too small to distinguish from the measurement uncertainty. Crowded, weak spectral features were left out of the quantitative analysis. The molecular orientations were averaged, while the calculations treated electronic channels independently and used fixed-nuclei assumptions. These limits bound the result: smaller vibrational effects can remain below the measurement’s resolution, and other molecules can behave differently.[1]
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