Related Experiment Video
Updated: Feb 22, 2026

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
Elucidating the origins of multimode vibrational coherences of polyatomic molecules induced by intense laser fields
Zhengrong Wei1, Jialin Li1, Lin Wang1
1Division of Chemistry and Biological Chemistry, and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.
Abstract:
Strong-field laser-molecule interaction forms much of the basis for initiating and probing ultrafast quantum dynamics. Previous studies aimed at elucidating the origins of vibrational coherences induced by intense laser fields have been confined to diatomic molecules. Furthermore, in all cases examined to date, vibrational wave packet motion is found to be induced by R-selective depletion; wave packet motion launched by bond softening, though theoretically predicted, remains hitherto unobserved. Here we employ the exquisite sensitivity of femtosecond extreme ultraviolet absorption spectroscopy to sub-picometer structural changes to observe both bond softening-induced vibrational wave packets, launched by the interaction of intense laser pulses with iodomethane, as well as multimode vibrational motion of the parent ion produced by strong-field ionization. In addition, we show that signatures of coherent vibrational motion in the time-dependent extreme ultraviolet absorption spectra directly furnish vibronic coupling strengths involving core-level transitions, from which geometrical parameters of transient core-excited states are extracted.Nuclear dynamics of polyatomic molecules involves multiple degrees of freedom and is challenging to explore. Here the authors study the internuclear distance-dependent depletion and bond-softening induced vibrational wavepacket dynamics of CH3I molecules using femtosecond XUV transient absorption spectroscopy.
Related Concept Videos
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to...
UV–Vis Spectroscopy: Molecular Electronic Transitions
IR Spectrum Peak Splitting: Symmetric vs Asymmetric Vibrations
Molecular Spectroscopy: Absorption and Emission
IR Absorption Frequency: Delocalization
In IR...

