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An attosecond molecular interferometer is proposed by using a XUV–XUV pump-probe scheme. The interferograms resulting in the photoelectron distributions enable the full reconstruction of the molecular wave packet associated to excited states using a quantum state holographic approach that, to our knowledge, has only been proposed for simple atomic targets combining attosecond XUV pulses with IR light. In contrast with existing works, we investigate schemes where one- and two-photon absorption paths contribute to ionize the hydrogen molecule and show that it is possible to retrieve the excitation dynamics even when imprinted in a minority channel. Furthermore, we provide a systematic analysis of the time-frequency maps that reveal the distinct, but tightly coupled, motion of electrons and nuclei. [ABSTRACT FROM AUTHOR]

Abstract: A pump‐probe experiment in the tetrafluoro‐methane (CF4) molecule has been theoretically simulated, allowing one to access electron dynamics in its natural time scale: the attosecond. The chosen pump and probe pulses can be currently produced in most attosecond laboratories. In this scheme, CF4 is first ionized by an extreme UV (XUV) attosecond pulse and the charge dynamics induced in the corresponding cation is probed with a few‐femtosecond visible light (VIS) pulse. We demonstrate that modulations in the calculated photoelectron spectra with the pump‐probe delay reflect the dynamics of the XUV‐induced electronic wave packet. In particular, from the analysis of these modulations in the interval of time delays where the pump and probe pulses do not overlap any more, one has access to the amplitudes and phases of the different components of the electronic wave packet generated by the attosecond pulse. These reflect a complex dynamics that basically consists of very fast charge fluctuations occurring all over the molecule without any preference for a particular molecular site. [ABSTRACT FROM AUTHOR]

We present a theoretical study of charge dynamics initiated by an attosecond XUV pulse in the glycine molecule, which consists in delocalized charge fluctuations all over the molecular skeleton. For this, we have explicitly used the actual electron wave packet created by such a broadband pulse. We show that, for the chosen pulse, charge dynamics in glycine is barely affected by nuclear motion or non adiabatic effects during the first 8 fs, and that the initial electronic coherences do not dissipate during the first 20 fs. In contrast, small variations in the initial nuclear positions, compatible with the geometries expected in the Franck-Condon region, lead to noticeable changes in this dynamics. [ABSTRACT FROM AUTHOR]

We investigate the use of UV-pump-UV-probe schemes to trace the evolution of nuclear wave packets in excited molecular states by analyzing the asymmetry of the electron angular distributions resulting from dissociative ionization. The asymmetry results from the coherent superposition of gerade and ungerade states of the remaining molecular ion in the region where the nuclear wave packet launched by the pump pulse in the neutral molecule is located. Hence, the variation of this asymmetry with the time delay between the pump and the probe pulses parallels that of the moving wave packet and, consequently, can be used to clock its field-free evolution. The performance of this method is illustrated for the H2 molecule. [ABSTRACT FROM AUTHOR]

time-dependent theoretical method is used to describe a UV pump-UV probe strategy to trace, at a femtosecond time scale, the motion of vibrational wave packets created in excited states of the hydrogen molecule by measuring single ionization probabilities. We use a spectral method to solve the time-dependent Schrödinger equation in full dimensionality, including correlation and all electronic and vibrational degrees of freedom. A pump pulse initially creates a vibrational wave packet in the intermediate electronic excited states of $$\hbox{H}_2$$. The frequency of the probe is chosen to ionize the target leaving the ion in a bound vibrational state. By varying the time delay between pulses, non-dissociative single ionization is enhanced or suppressed. Energy differential ionization probabilities are reported and compared with a model based on the Franck-Condon approximation. [ABSTRACT FROM AUTHOR]

With the advent of attosecond light pulses at the beginning of this century, the possibility to perform real‐time observations of electron motion in molecules has spurred impressive theoretical developments aimed at providing support and guidance to numerous, but still incipient, experimental efforts devoted to understand chemistry at its ultimate temporal frontier: the attosecond. The first real‐time observation of electron dynamics in a relatively large molecule, phenylalanine, was reported in 2014. This would have been difficult without the help of theory, since observations in this emerging field, recently coined attochemistry, are still indirect. While standard Quantum Chemistry methods can describe excited bound‐state dynamics, new approaches incorporating scattering theory formalisms are needed to understand the interaction with attosecond pulses. Indeed, due to their short wavelengths, lying in the XUV and X‐ray spectral regions, the interaction of such pulses with any molecule inevitably leads to ionization, which requires describing the molecular ionization continuum. Also, because of their short duration (i.e., large bandwidth), ionization is accompanied by the formation of a molecular electronic wave packet (i.e., a coherent superposition of electronic states), which evolves in time and dictates the fate of the molecule at the longer time scales where chemistry shows up. Although much has already been done up to date, current bottlenecks in the field are to account for electron correlations during the ionization process and for the coupled electron and nuclear dynamics that follows. Past and ongoing theoretical efforts are described here along with experimental work towards the solid establishment of attochemistry. This article is categorized under: Electronic Structure Theory > Ab Initio Electronic Structure MethodsSoftware > Quantum ChemistryTheoretical and Physical Chemistry > Spectroscopy [ABSTRACT FROM AUTHOR]