Photoelectron Soft X-Ray Fluorescence Coincidence Spectroscopy on Free Molecules

A technique for measuring core-level photoemission from free molecules in coincidence with the soft x-ray fluorescence decay is presented. Zero-kinetic-energy photoelectrons are detected in a time-of-flight electron spectrometer, and photons are collected in a large solid angle by a detector situated close to the interaction region. The coincidence spectrum of N2 shows an adiabatic 1s line, free from electron-electron postcollision interaction effects. The results open up new aspects on core-hole excitation-emission dynamics