Femtosecond resolution ultrafast ion reaction time measurement a pulsed‐laser field desorption time‐of‐flight spectroscopy

Abstract

Using a pulsed‐laser field desorption technique and an ion reaction time amplification scheme for the time‐of‐flight spectroscopy, dissociation by atomic tunneling of 4HeRh2+ in a field of ∼3 to 4.5 V/A has been measured to be 790±21 fs. This is the time for the ion to rotate 180°. A strong isotope effect by replacing 4He with 3He confirms the ion reaction to be produced by atomic tunneling of a mass dependent potential barrier.