Attochemistry: Is Controlling Electrons the Future of Photochemistry?

Abstract

Controlling matter with light has always been a great challenge, leading to the ever-expanding field of photochemistry. In addition, since the first generation of light pulses of attosecond (1 as = 10 −18 s) duration, a great deal of efforts has been devoted to observing and controlling electrons on their intrinsic timescale. Because of their short duration, attosecond pulses have a large spectral bandwidth populating several electronically excited states in a coherent manner, i.e., an electronic wavepacket. Due to interference, such a wavepacket has a new electronic distribution implying a potentially different and totally new reactivity as compared to traditional photochemistry, and leading to the novel concept of "attochemistry". This nascent field requires the support of theory right from the start. In this Perspective, we discuss the opportunities offered by attochemistry, the related challenges, as well as the current and future state-of-art developments in theoretical chemistry needed to model it accurately.

Carrier-envelope-phase measurement of sub-cycle UV pulses using angular photofragment distributions

“…Moreover, the few-cycle attosecond laser pulses with carrier-envelope-phase (CEP) open the possibilities to capture and steer the dynamics at sub-cycle duration 4,5 . Few-cycle CEP-locked infrared (IR) pulses, especially its combination with an isolated attosecond extreme ultraviolet (XUV) pulse, have been explored by many groups and boosted ultrafast science into versatile degrees of freedom 2 , as for example, manipulating electron localization in molecular dissociation ionization 6 , steering charge localization following molecular photoionization 7 , quantum-phase control of absorption profile 8 , and many others about electronic dynamics in photoexcitation, photoionization and photoabsorption processes [9][10][11][12][13][14][15] . From the other side, these dynamics of the quantum systems induced by sub/few-cycle attosecond ultraviolet (UV) pulses can be used for an accurate characterization of these pulses.…”

Time evolution of entanglement of electrons and nuclei and partial traces in ultrafast photochemistry

“…It is made possible by the ultrafast optical excitation. [27][28][29] Ultrafast attosecond photoionization and the resulting entanglement between the photoelectron and a cation can also be used to probe the vibrational coherences of the cation. 30 To solve the dynamics it is practical to represent the Hamiltonian and other operators as matrices in a finite basis.…”

“…It is made possible by the ultrafast optical excitation. 27–29 Ultrafast attosecond photoionization and the resulting entanglement between the photoelectron and a cation can also be used to probe the vibrational coherences of the cation. 30…”

Tracing the vibrational dynamics of sodium iodide via the spectrum of emitted photofragments

“…29 This allows not only to monitor but also to control chemical reactions, which is the ultimate goal of attochemistry. 30 The imaging techniques presented above have been applied mostly to observe molecular motion in excited electronic states. Monitoring nuclear dynamics in the ground electronic state is not considered too frequently as the preparation of initial vibrational wave packets in the ground state is, in general, more cumbersome than in the excited state.…”