Figure 1.

Map of ¹H spin noise spectra of the sample acetone:acetonitrile:chloroform (1:0.07:0.17)+5 % [D₆]DMSO by volume, recorded on a 500 MHz Bruker DRX spectrometer equipped with a TXI cryo-probe for different tuning and matching positions. The bold traces are noise signals of acetone, which were deconvolved to avoid interference caused by the narrow superimposed signals of the ¹³C satellites and of acetonitrile. Tuning/matching combinations, where spin noise signals form dips, are indicated by red frames. The FSTO (as found through small-flip angle pulse spectra, see Supporting Information) is highlighted in yellow, while a cyan-colored frame denotes the conventional tuning optimum (CTO), where γB₁ is maximum. Different shades of grey indicate the circuit’s thermal noise power level at each position (darker greys correspond to higher values).