Beta-delayed proton precursors with 59≦Z≦62

The new, beta-delayed proton emitters¹²⁸Pr(3.2 _?0.4 ^+0.5 s),¹³⁰Pm(2.2 _?0.4 ^+0.6 s), and¹³²Pm(5.0 _?0.6 ^+0.8 s) have been observed at the on-line isotope separator OASIS. Also studied were¹²⁹Nd and¹³³Sm. Our on-going study of the decay properties of very neutron-deficient lanthanides has led to detailed information about beta-delayed proton emitters with 59≤Z≤62. The isotopes were produced at the SuperHILAC's on-line isotope separator OASIS [1] in reactions of⁴⁰Ca projectiles on⁹²Mo and⁹⁶Ru targets enriched to >95%. Decay studies were carried out in a low background spectroscopy laboratory. The isotope of interest was passed through a slit in the focal plane of the mass separator, transported ionoptically to a fast cycling tape, and periodically positioned between a silicon charged particle telescope, a HPGe x-ray detector, and a GAMMA-X Ge detector. Decays involving beta-delayed gamma rays and protons along with any coincident positrons, x-rays and gamma rays were measured event-by-event and written to computer tape for subsequent replay and analysis.     

Dithienylethene-Based Single Molecular Photothermal Linear Actuator

By employing a mechanically controllable break junction technique, we have realized an ideal single molecular linear actuator based on dithienylethene (DTE) based molecular architecture, which undergoes reversible photothermal isomerization when subjected to UV irradiation under ambient conditions. As a result, open form (compressed, UV OFF) and closed form (elongated, UV ON) of dithienylethene-based molecular junctions are achieved. Interestingly, the mechanical actuation is achieved without changing the conductance of the molecular junction around the Fermi level over several cycles, which is an essential property required for an ideal single molecular actuator. Our study demonstrates a unique example of achieving a perfect balance between tunneling width and barrier height change upon photothermal isomerization, resulting in no change in conductance but a change in the molecular length, which results in mechanical actuation at the single molecular level.