High resolution slice imaging of a molecular speed distribution

High resolution slice imaging experiments are reported measuring the speed distribution of molecular fragments, recoiling at a most probable speed v(mp), with a full-width-half-maximum (FWHM) speed resolution near the permille level: FWHMv/v(mp) = 1.9 X 10(-3). We implemented a high resolution single-particle slice imaging detector and used a two-colour resonance-enhanced multi-photon ionisation (REMPI) scheme to reduce broadening of the speed distribution due to the electron kick. The results on the measurement of the CD3 speed distribution from photolysis of CD3I show that it is possible to image the three-dimensional speed distribution at a resolution down to FWHMv = 6.7 m s(-1), when the fragment has an absolute speed of v(mp) = 3473 m s(-1). The new experiments demonstrate the potential of slice imaging to measure with high resolution the three-dimensional speed distribution of a cloud of molecules.