Fig. 2
Experimentally measured harmonic signals. a–c are the spatially resolved harmonic spectra of Ar, H2, and D2. d shows the spatially integrated HHG signals for the spectra in a (dash-dotted line), b (solid line), and c (dashed line), respectively. For clarity, the dash-dotted line is multiplied by a factor of 0.2. e–h are the normalized harmonic signals of H15-H21 for Ar (dash-dotted line), H2 (solid line), and D2 (dashed line), respectively. Here, the laser intensity is 1.5 × 1014 W cm−2 and the pulse duration is 30 fs
