Experimental comparison of frustrated tunnel ionisation in multi-cycle and few-cycle pulses

We present the first experimental evidence which qualitatively shows that frustrated tunnel ionization results in a larger number of excited neutrals per a tunnelling event for 6 fs pulses compared to 30 fs pulses. In addition, we also observe a less severe dependence on elliptical polarization for the 6 fs pulses. Furthermore, by varying the carrier envelope phase of the shorter pulse, we observe a modulation in the yield of excited neutrals which indicates possible control of electron trajectories.