A team of Chinese researchers has revealed that the noncyclic 3-D structure of water droplets starts to endure with pentamers at low finite temperatures. The team has developed a method of infrared spectroscopy of neutral clusters based on a tunable vacuum ultraviolet free-electron laser (VUV-FEL). This method forms a new standard for the study of vibrational spectra of a wide variety of neutral clusters that could not be analyzed previously. Using the VUV-FEL-based IR scheme, researchers measured the IR spectra of size-selected neutral water clusters. The breakthrough sheds light on the structural diversity of the hydrogen-bonding networks that are accountable for the major structural characteristics and properties of water in the condensed form.