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Coherent Control of Photofragment Distributions Using Laser Phase Modulation in the Weak-Field Limit

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Coherent Control of Photofragment Distributions Using Laser Phase Modulation in the Weak-Field Limit


Niels E. Henriksen1

1Department of Chemistry, Technical University of Denmark, Building 207, Lyngby, Denmark

Recently, the possibility of quantum interference control of photochemical reactions in the weak-field limit has been discussed [1-4]. To that end, we demonstrate quantum interference control of the final state distributions of photodissociation fragments by means of pure phase modulation of the pump laser pulse in the weak-field regime [4-6]. One example is based on realistic wave packet calculations of the transient vibrational populations of the Br2(B,vf) fragment produced upon predissociation of the Ne-Br2(B) complex, which is excited to a superposition of overlapping resonance states using pulses with different phase modulation. Transient phase effects on the fragment populations are found to persist for long times (more than 50 ps) after the pulse is over. Another example is the non-adiabatic process: I + Br*  ←  IBr  →  I + Br, where the relative yield of excited Br* can be changed by pure phase modulation. This control can be extended beyond transient effects to “infinite time” by weak-field excitation via the bound A state of IBr.

References:

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[5] A.K. Tiwari, D. Dey, and N.E. Henriksen, Phys. Rev. A, 89, 023417 (2014).

[6] A. García-Vela and N.E. Henriksen, J.Phys.Chem.Lett. 6, 824 (2015).