2023/11/23 by Zinchenko, Kristina S., Ardana-Lamas, Fernando, Lanfaloni, Valentina Utrio +5
#Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Optics (physics.optics)
paper · doi:10.48550/arxiv.2311.14013
The Jahn-Teller effect (JTE) is central to the understanding of the physical and chemical properties of a broad variety of molecules and materials. Whereas the manifestations of the JTE on stationary properties of matter are relatively well studied, the study of JTE-induced dynamics is still in its infancy, largely owing to its ultrafast and non-adiabatic nature. For example, the time scales reported for the distortion of CH4+ from the initial T\rm d geometry to a nominal C\rm 2v relaxed structure range from 1.85~fs over 10±2~fs to 20±7~fs. Here, by combining element-specific attosecond transient-absorption spectroscopy and quantum-dynamics simulations, we show that the initial electronic relaxation occurs within 5~fs and that the subsequent nuclear dynamics are dominated by the Q2 scissoring and Q1 symmetric stretching modes, which dephase in 41±10~fs and 13±3~fs, respectively. Significant structural relaxation is found to take place only along the e-symmetry Q2 mode. These results demonstrate that CH4+ created by ionization of CH4 is best thought of as a highly fluxional species that possesses a long-time-averaged vibrational distribution centered around a D\rm 2d structure. The methods demonstrated in our work provide guidelines for the understanding of Jahn-Teller driven non-adiabatic dynamics in other, more complex systems.