Quantum Phase Analysis of Field-Free Molecular Alignment

TL;DR

This paper uses quantum phase analysis to explain complex phenomena in field-free molecular alignment induced by femtosecond laser pulses, revealing the physical origins of observed alignment behaviors.

Contribution

It provides a quantum mechanical explanation for phenomena in molecular alignment, highlighting the role of quantum phases in understanding alignment peaks and transitions.

Findings

Alignment peaks occur periodically with species-dependent shapes

Maximum alignment does not occur at the first peak

Transitions between aligned and anti-aligned states are very rapid

Abstract

We present quantum mechanical explanations for unresolved phenomena observed in field-free molecular alignment by a femtosecond laser pulse. Quantum phase analysis of molecular rotational states reveals the physical origin of the following phenomena: strong alignment peaks appear periodically, and the temporal shape of each alignment peak changes in an orderly fashion depending on molecular species; the strongest alignment is not achieved at the first peak; the transition between aligned and anti-aligned states is very fast compared to the time scale of rotational dynamics. These features are understood in a unified way analogous to that describing a carrier-envelope-phase-stabilized mode-locked laser.