Fig. 4: Benchmarking measurements.
Each row shows the time-gated electric field on the left and its Fourier-transformed spectrum on the right. a, The light-grey field represents atmospheric water molecules at 50% RH (16.5 μmol), while the black curve represents 8% RH (2.64 μmol). b, Two absorption modes are visible: a fundamental mode at 0.115 PHz and a combination band at 0.16 PHz. c, Liquid water molecules at 5.23 μmol (red) and 2.64 μmol (pink) along with pure acetic acid (brown) as a reference measurement. d, The molecular response of pure acetic acid is compared with that of aqueous solutions. e, Pure liquid ethanol at different volumes of 4.13 μmol, 16.5 μmol and 82.5 μmol. f, The weak combination peak centred at 0.130 PHz is observed at all three volumes.
