Related Experiment Video
Updated: Sep 6, 2025

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
Unimolecular dissociation dynamics of electronically excited HCO(Ã2A''): rotational control of nonadiabatic decay
Ge Sun1, Shanyu Han2, Xianfeng Zheng1,3
1Department of Chemistry, University of California Riverside, Riverside, CA 92521, USA. jszhang@ucr.edu.
Abstract:
The photoinduced unimolecular decay of the electronically excited HCO(Ã2A'') is investigated in a combined experimental-theoretical study. The molecule is excited to the (1, n2, 0) combination bands, which decay via Renner-Teller coupling to the ground electronic state. The rovibrational state distribution of the CO fragment was measured via the high-n Rydberg H-atom time-of-flight method and calculated using a wave packet method on an accurate set of potential energy surfaces. It is shown that the non-adiabatic decay rate is strongly modulated by the HCO rotational angular momentum, which leaves unique signatures in the product state distribution. The experimentally observed bimodal rotational distribution of the dominant CO(v = 0) fragment is likely due to decay of different vibronic states populated by the excitation and modulated by the excited state lifetime, which is in turn controlled by the parent rotational quantum number.
Related Concept Videos
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control
¹³C NMR: ¹H–¹³C Decoupling
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
Double Resonance Techniques: Overview
Spin decoupling is usually achieved by...
Spin–Spin Coupling Constant: Overview
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
Deactivation Processes: Jablonski Diagram

