Absolute absorption spectroscopy based on molecule interferometry

TL;DR

This paper introduces a novel interferometry-based method for measuring absolute photon absorption cross sections of neutral molecules, independent of beam density and fragmentation, enabling high-precision measurements even in dilute beams.

Contribution

The paper presents a new interferometry technique that allows for absolute absorption measurements without requiring knowledge of particle density or relying on fragmentation.

Findings

Method is feasible with existing technology.

High precision achievable in dilute molecular beams.

Applicable to internal state conversion and fluorescence detection.

Abstract

We propose a new method to measure the absolute photon absorption cross section of neutral molecules in a molecular beam. It is independent of our knowledge of the particle beam density, nor does it rely on photo-induced fragmentation or ionization. The method is based on resolving the recoil resulting from photon absorption by means of near-field matter-wave interference, and it thus applies even to very dilute beams with low optical densities. Our discussion includes the possibility of internal state conversion as well as fluorescence. We assess the influence of various experimental uncertainties and show that the measurement of absolute absorption cross sections is conceivable with high precision and using existing technologies.