Existence of Terahertz Rotors Detected in a Metal - Organic Framework

Existence of Terahertz Rotors Detected in a Metal-Organic Framework [2017]

 

 

Vibrations with a frequency of 1,000,000,000,000 oscillations per second — which scientists called the “Terahertz modes” — are playing a fundamental role in controlling the structural sturdiness and functions of porous materials, down to the molecular level. In this study published in PRL, we present the outcomes of an international collaborative effort, comprising large-scale experiments conducted at the high-resolution pulsed neutron source and third generation synchrotron radiation facility, in tandem with computational modeling studies to pinpoint the existence of Terahertz modes in a porous MOF structure. We show and explain, for the first time, the basis for a number of exhilarating vibrational motions intrinsic to MOF: (i) Rotational actions reminiscent to that of a hindered propeller (see clips above: computed by density-functional theory, DFT); (ii) Bouncing motions akin to that of a trampoline, and, (iii) Rocking movements of an unhinged framework produced by a shearing action. We have discovered that collective Terahertz motions are indeed ubiquitous in MOF materials, which could serve as a unique nanoscale platform not only to probe core physical mechanisms, but also to interrogate new phenomena previously thought to be intractable.