Coherent Quantum Control of $S_2 \leftrightarrow S_1$ Internal Conversion in Pyrazine via $S_0 \to S_2/S_1$ Weak Field Excitation

TL;DR

This paper demonstrates how shaping laser pulses can coherently control the internal conversion process between $S_2$ and $S_1$ states in pyrazine, optimizing excitation and decay pathways simultaneously.

Contribution

It introduces a resonance-based control approach to manipulate internal conversion in pyrazine through laser pulse shaping, considering excitation and decay together.

Findings

Successful control achieved by optimizing laser amplitude and phase profiles.

Control effectiveness depends on resonance properties in $S_2$.

Resonance-based shaping enhances internal conversion manipulation.

Abstract

Coherent control of internal conversion (IC) between the first ($S_1$) and second ($S_2$) singlet excited electronic states in pyrazine, where the $S_2$ state is populated from the ground singlet electronic state $S_0$ by weak field excitation, is examined. Control is implemented by shaping the laser which excites $S_2$. Excitation and IC are considered simultaneously, using the recently introduced resonance-based control approach. Highly successful control is achieved by optimizing both the amplitude and phase profiles of the laser spectrum. The dependence of control on the properties of resonances in $S_2$ is demonstrated.