Abstract
Understanding the evolution of molecular electronic structures is the key to explore and control photochemical reactions and photobiological processes. Subjected to strong laser fields, electronic holes are formed upon ionization and evolve in the attosecond timescale. It is crucial to probe the electronic dynamics in real time with attosecond-temporal and atomic-spatial precision. Here, we present molecular attosecond interferometry that enables the in situ manipulation of holes in carbon dioxide molecules via the interferometry of the phase-locked electrons (propagating in opposite directions) of a laser-triggered rotational wave packet. The joint measurement on high-harmonic and terahertz spectroscopy (HATS) provides a unique tool for understanding electron dynamics from picoseconds to attoseconds. The optimum phases of two-color pulses for controlling the electron wave packet are precisely determined owing to the robust reference provided with the terahertz pulse generation. It is noteworthy that the contribution of HOMO-1 and HOMO-2 increases reflecting the deformation of the hole as the harmonic order increases. Our method can be applied to study hole dynamics of complex molecules and electron correlations during the strong-field process. The threefold control through molecular alignment, laser polarization, and the two-color pulse phase delay allows the precise manipulation of the transient hole paving the way for new advances in attochemistry.
Highlights
Since the late 1980s, time-resolved femtosecond techniques have led to tremendous developments in observing and manipulating chemical reactions at a timescale shorter than the period of vibration and rotation, i.e., to form or break chemical bonds in real time [1,2,3,4]
When a weak second-harmonic pulse is added, an additional phase between the consecutive half-cycles of the Michelson interferometry breaks the time-reversal symmetry of the electron wave packets (EWPs) and leads to the generation of even harmonics (Figure 2(b)) [25] and the THz wave (Figure 2(c)) [30]. Because they are inherently phase-locked from strong field interactions, the joint measurement of harmonic and terahertz spectroscopy (HATS) offers an unusual opportunity to observe electron or hole dynamics in multiple dimensions
The present research demonstrates how to probe the ultrafast deformation of a molecular hole from threefold control using molecular attosecond interferometry
Summary
Since the late 1980s, time-resolved femtosecond techniques have led to tremendous developments in observing and manipulating chemical reactions at a timescale shorter than the period of vibration and rotation, i.e., to form or break chemical bonds in real time [1,2,3,4]. Coupling among electrons or between nuclei and electrons helps to realize a subfemtosecond-timescale manipulation of electron and hole dynamics [12, 13], which is pivotal for controlling the chemical reactions that follow. A redox reaction is an ultrafast process of gaining and losing electrons [14]. Manipulation of these electrons can migrate a localized charge, thereby forming new chemical bonds between molecules [15]
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