Molecular echoes in space and time

TL;DR

This paper presents a novel spatiotemporal analysis of molecular alignment echoes using coincidence Coulomb explosion imaging, revealing new spatially rotated and imaginary echoes, advancing understanding of molecular echo phenomena.

Contribution

It introduces the first direct imaging of molecular alignment echoes, uncovering previously unreported spatially rotated and imaginary echoes, and explores their dependence on pulse polarization.

Findings

Discovery of spatially rotated echoes dependent on polarization

Observation of imaginary echoes at negative times

First direct imaging of molecular alignment echoes

Abstract

Mountain echoes are a well-known phenomenon, where an impulse excitation is mirrored by the rocks to generate a replica of the original stimulus, often with reverberating recurrences. For spin echoes in magnetic resonance and photon echoes in atomic and molecular systems the role of the mirror is played by a second, time delayed pulse which is able to reverse the ow of time and recreate the original event. Recently, laser-induced rotational alignment and orientation echoes were introduced for molecular gases, and discussed in terms of rotational-phase-space filamentation. Here we present, for the first time, a direct spatiotemporal analysis of various molecular alignment echoes by means of coincidence Coulomb explosion imaging. We observe hitherto unreported spatially rotated echoes, that depend on the polarization direction of the pump pulses, and find surprising imaginary echoes at negative times.