Researchers have developed a method for making simultaneous soft X-ray absorption spectroscopy (XAS) measurements of solid-liquid interfaces and bulk liquids. By controlling the thickness of the liquid layer, they obtained the O K-edge XAS spectrum of bulk H2O from a liquid H2O layer on a thin Au film using the transmission method, and they used the electron-yield method to obtain the XAS spectrum of the H2O/Au interface by measuring the drain currents from the Au surface following soft X-ray absorption. This method for obtaining simultaneous XAS measurements of solid-liquid interfaces and bulk liquids can be utilized to investigate the mechanisms of a variety of catalytic, electrochemical, and biological reactions involving solid-liquid interfaces.

Gravitational waves are tiny ripples in spacetime. Their first direct detection in 2015 marked a revolutionary moment in astronomy. Today, we have a thorough understanding of signals that travel far from their sources through quiet, nearly empty space, such as those emitted when black holes merge. In this case, the wave can be considered a minor disturbance on a silent background. The distinction between “background” and “wave” is clear, and the quantity measured by the detector—a tiny stretching and squeezing—is clearly determined.