Ultrafast Charge Transfer of a Valence Double Hole in Glycine Driven Exclusively by Nuclear Motion

Abstract

We explore theoretically the ultrafast transfer of a double electron hole between the functional groups of glycine after K-shell ionization and subsequent Auger decay. Although a large energy gap of about 15 eV initially exists between the two electronic states involved and coherent electronic dynamics play no role in the hole transfer, we find that the double hole is transferred within 3 to 4 fs between both functional ends of the glycine molecule driven solely by specific nuclear displacements and non-Born-Oppenheimer effects. The nuclear displacements along specific vibrational modes are of the order of 15% of a typical chemical bond between carbon, oxygen, and nitrogen atoms and about 30% for bonds involving hydrogen atoms. The time required for the hole transfer corresponds to less than half a vibrational period of the involved nuclear modes. This finding challenges the common wisdom that nuclear dynamics of the molecular skeleton are unimportant for charge transfer processes at the few-femtosecond time scale and shows that they can even play a prominent role. It also indicates that in x-ray imaging experiments, in which ionization is unavoidable, valence electron redistribution caused by nuclear dynamics might be much faster than previously anticipated. Thus, non-BornOppenheimer effects may affect the apparent electron densities extracted from such measurements.

Characterizing attosecond pulses in the soft x-ray regime

“…Besides the unprecedented temporal resolution, x-rays offer the ability to study the electronic environment around a specific atomic site within the material [9], and brings core-hole spectroscopy into the attosecond regime [10]. Attosecond x-ray pulses may find many applications in studies ranging from multi-orbital electronic dynamics [11] non-Born-Oppenheimer dynamics [12,13], charge-transfer processes in photochemical reactions [14] to structural [15] as well as insulator-metal [16,17] phase transitions in condensed matter systems.…”

Determination of Energy-Transfer Distributions in Ionizing Ion-Molecule Collisions

“…Ultrafast nuclear rearrangements have been also observed in pump-probe experiments [5]; such processes compete with the expected charge separation in multiply charged molecules [6][7][8]. Therefore, a detailed knowledge of the response of complex molecular systems to ionization or excitation and its influence on chemical reactivity is still a relevant topic today [9,10]. In this context, recent combined experimental and theoretical works have been very valuable in providing pictures of the ion-induced ionization or fragmentation of complex molecular systems [7,8,11,12].…”

Density matrix-based time-dependent configuration interaction approach to ultrafast spin-flip dynamics

“…Here, the nuclei are fixed at the ground state equilibrium positions, and thus we solve the electronic Schrödinger equation only. The question whether the nuclear motion can be neglected for the early-time dynamics has triggered an ongoing debate [27][28][29][30]. Here, we assume that the system is excited far from conical intersections and that the considered time interval is shorter than the relevant vibrational periods.…”