Attosecond Probing of Coherent Vibrational Dynamics in CBr${}_4$

Abstract

A coherent vibrational wavepacket is launched and manipulated in the symmetric stretch (a${}_1$) mode of CBr${}_4$, by impulsive stimulated Raman scattering from non-resonant 400 nm laser pump pulses with various peak intensities on the order of tens of 10${}^{12}$ W/cm${}^2$. Extreme ultraviolet (XUV) attosecond transient absorption spectroscopy (ATAS) records the wavepacket dynamics as temporal oscillations in XUV absorption energy at the bromine M${}_{4,5}$ 3d${}_{3/2,5/2}$ edges around 70 eV. The results are augmented by nuclear time-dependent Schrödinger equation simulations. Slopes of the (Br-3d${}_{3/2,5/2}$)${}^{-1}$10a${}_1^{\ast }$ core-excited state potential energy surface (PES) along the a${}_1$ mode are calculated to be -9.4 eV/Å from restricted open-shell Kohn-Sham calculations. Using analytical relations derived for the small-displacement limit with the calculated slopes of the core-excited state PES, a deeper insight into the vibrational dynamics is obtained by retrieving the experimental excursion amplitude of the vibrational wavepacket and the amount of population transferred to the vibrational first-excited state, as a function of pump-pulse peak intensity. Experimentally, the results show that XUV ATAS is capable of easily resolving oscillations in the XUV absorption energy on the order of few to tens of meV and tens of femtosecond time precision, limited only by the averaging times in the experimental scans. This corresponds to oscillations of C-Br bond length on the order of 10${}^{-4}$ to 10${}^{-3}$ Å. The results and the analytic relationships offer a clear physical picture, on multiple levels of understanding, for how the pump-pulse intensity controls the vibrational dynamics launched by non-resonant ISRS in the small-displacement limit.

References in corpus (6)

• Highly Accurate Prediction of Core Spectra of Molecules at Density Functional Theory Cost: Attaining sub eV Error from a Restricted Open-Shell Kohn-Sham Approach
• Decoherence and Revival in Attosecond Charge Migration Driven by Non-adiabatic Dynamics
• Relativistic Orbital Optimized Density Functional Theory for Accurate Core-Level Spectroscopy
• Coherent electronic-vibrational dynamics in deuterium bromide probed via attosecond transient absorption spectroscopy
• Core-excited states of SF${}_6$ probed with soft X-ray femtosecond transient absorption of vibrational wavepackets
• Measurement of Coherent Vibrational Dynamics with X-ray Transient Absorption Spectroscopy Simultaneously at the Carbon K- and Chlorine L${}_{2,3}$- Edges

Cited by in corpus (1)

• Different Rise Times of Atomic Br M${}_{4,5}$ 3d${}_{3/2,5/2}$ Core Level Absorptions during Br${}_2$ C ${}^1{\Pi }_u$ $1_u$ State Dissociation via Extreme Ultraviolet Transient Absorption Spectroscopy