Moran Geva | Searcharxiv

arXiv2023

Weak-Field Coherent Control of Ultrafast Molecule Making

Coherent control of ultrafast molecule making from colliding reactants is crucial for realizing coherent control of binary photoreactions (CCBP). To handle diverse excitation scenarios, feasibility with both weak and strong fields is essential. We experimentally demonstrate here the weak-field feasibility, achieving it even under thermally hot conditions typical of chemical reactions. The making of KAr molecules from hot pairs of colliding K and Ar atoms via resonance-mediated two-photon excitation is controlled by weak linearly-chirped femtosecond pulses. Negative chirps enhance the yield. Our experimental and ab initio results are in excellent agreement. New routes to CCBP are opened.

physics.chem-ph↗

arXiv2021

Coherent Control of Ultrafast Bond Making and Subsequent Molecular Dynamics: Demonstration of Final-State Branching Ratio Control

Quantum coherent control of ultrafast bond making and the subsequent molecular dynamics is crucial for the realization of a new photochemistry, where a shaped laser field is actively driving the chemical system in a coherent way from the thermal initial state of the reactants to the final state of the desired products. We demonstrate here coherent control over the relative yields of Mg$_2$ molecules that are generated via photoassociation and subsequently photodriven into different groups of final states. The strong-field process involves non-resonant multiphoton femtosecond photoassociation of a pair of thermally hot magnesium atoms into a bound Mg$_{2}$ molecule and subsequent molecular dynamics on electronically excited states. The branching-ratio control is achieved with linearly chirped laser pulses, utilizing the different chirp dependence that various groups of final molecular states display for their post-pulse population. Our study establishes the feasibility of high degree coherent control over quantum molecular dynamics that is initiated by femtosecond photoassociation of thermal atoms.

physics.atom-ph↗