Monitoring the effect of a control pulse on a conical intersection by time-resolved photoelectron spectroscopy

Abstract

We have previously shown how femtosecond angle-and energy-resolved photoelectron spectroscopy can be used to monitor quantum wavepacket bifurcation at an avoided crossing or conical intersection and also how a symmetry-allowed conical intersection can be effectively morphed into an avoided crossing by photo-induced symmetry breaking. The latter result suggests that varying the parameters of a laser to modify a conical intersection might control the rate of passage of wavepackets through such regions, providing a gating process for different chemical products. In this paper, we show with full quantum mechanical calculations that such optical control of conical intersections can actually be monitored in real time with femtosecond angle-and energy-resolved photoelectron spectroscopy. In turn, this suggests that one can optimally control the gating process at a conical intersection by monitoring the photoelectron velocity map images, which should provide far more efficient and rapid optimal control than measuring the ratio of products. To demonstrate the sensitivity of time-resolved photoelectron spectra for detecting the consequences of such optical control, as well as for monitoring how the wavepacket bifurcation is affected by the control, we report results for quantum wavepackets going through the region of the symmetry-allowed conical intersection between the first two 2 A 0 states of NO 2 that is transformed to an avoided crossing. Geometry-and energy-dependent photoionization matrix elements are explicitly incorporated in these studies. Time-resolved photoelectron angular distributions and photoelectron images are seen to systematically reflect the effects of the control pulse.

Electronic and nuclear flux analysis on nonadiabatic electron transfer reaction: A view from single‐configuration adiabatic born–huang representation

“…We also have found characteristic phenomena emerging from the electron transfer in alkali halides, with use of the full quantum mechanical methodology both for electrons and nuclei. The phenomena revealed include (i) direct observation of wavepacket bifurcation associated with nonadiabatic transitions in terms of femtosecond time‐resolved photoelectron spectroscopy, (ii) optical controllability of nonadiabatic transitions using the dynamical Stark effect or by symmetry braking of symmetry‐allowed conical intersection, (iii) anomalous photon emission by applying CW lasers on the intramolecular electron transfer systems, and (iv) laser‐assisted confinement of quantum wavepackets by the CW laser induced Floquet states coupled with the intrinsic nonadiabatic interactions, and so on.…”

Electronic quantum effects mapped onto non-Born-Oppenheimer nuclear paths: Nonclassical surmounting over potential barriers and trapping above the transition states due to nonadiabatic path-branching

“…24 For a high-energy passage across nonadiabatic regions, the surface hopping model is well accepted to conveniently describe nonadiabatic jump within the (classical) path dynamics. [25][26][27][28][29][30][31] On the other hand, it has been revealed by full-quantum studies [32][33][34] and experiments [35][36][37] that the passage of quantum wavepackets across nonadiabatic regions (avoided crossing and conical intersection) can be directly observed. In particular, the theory of time-resolved photoelectron spectroscopy has illustrated how the wavepacket bifurcations can be reflected in the photoelectron signals and how they can be dynamically controlled.…”

“…In particular, the theory of time-resolved photoelectron spectroscopy has illustrated how the wavepacket bifurcations can be reflected in the photoelectron signals and how they can be dynamically controlled. [32][33][34]38 The wavepacket bifurcation is indeed essential because it is a manifestation of electron-nuclear quantum entanglement induced by nonadiabatic interactions.…”

Lorentz-like force emerging from kinematic interactions between electrons and nuclei in molecules: A quantum mechanical origin of symmetry breaking that can trigger molecular chirality

“…5-7 for excellent reviews and the mathematical aspects), but we are more concerned with novel phenomena that arise from nonadiabatic interactions themselves. As such we have delineated, for instance, the direct observation of bifurcation of quantum mechanical wavepackets, [8][9][10][11][12][13][14][15] emergence of chaotic dynamics through bifurcation and merging of the vibrational wavepackets, 16,17 modulation and control of nonadiabatic interactions themselves such as the modification of the so-called symmetryallowed conical intersection by shining a laser in such a manner to break the relevant symmetry, 18,19 control of the crossing point making use of the dynamical Stark effects, [20][21][22] characteristic photon emission from a molecule of nonadiabatic intramolecular electron transfer that is placed in a CW laser field, [23][24][25][26] nonadiabatic electron wavepacket dynamics along branching paths, 3,[27][28][29][30][31][32][33][34][35][36] and so on. We here discuss another aspect of nonadiabatic interaction in breaking molecular symmetry.…”