Fig. 3: Measured harmonic emission times and VUV attosecond pulses.
a Measured harmonic spectrum (black line gray-filled area) and the emission times \({t}_{e}^{(q)}\) (red triangles). In the plot we have set \({t}_{e}^{(q=13)}=0\). b Dependence of the photoelectron harmonic yield on the delay between the VUV and M-IR pulses (raw data as dots, bandpass-filtered data as lines) obtained from the spectrogram in Fig. 1b. The photoelectron peaks oscillate with the frequency of the M--IR field ω0. The shift between the maxima of the harmonic photoelectron yield corresponds to the harmonic emission times (shown in (a)) which have been used to obtain the harmonic phase distribution. c Average temporal profile of the attosecond pulses constituting the attosecond pulse train. The blue-dashed line depicts the attosecond pulse in the attosecond pulse train in the case of Fourier Transform Limited (FTL). The red line shows the average attosecond pulse in the attosecond pulse train obtained using the measured phases. The duration of the measured pulse in the train is \({\tau }_{q=13...23}^{{{\rm{meas}}}.}\approx 950\) asec.
