A local versus non-local t-matrix in the N(p, 2p)C reaction at 46 MeV

The angular distributions for the ¹⁴N(p, 2p)¹³C reactions at 46 MeV incident proton energy are calculated in the distorted wave t-matrix approximation (DWTA) where approximate optical-model waves are used. A comparison is made between the calculation using a local t-matrix to that of a non-local t-matrix. The (p, 2p) angular distribution is smaller in magnitude where a non-local t-matrix is employed compared to the calculation using a local t-matrix which implies that there is an overall enhancement of absorption associated with the non-local t-matrix. This also implies that differences between the local and non-local off-energy-shell effects can be significant. Parameter studies were undertaken for the distorted waves and bound state wave function and the effects on the angular distributions were similar in the local and non-local cases. The distortion effect due to the final-state focus phase dramatically changes the shape of the angular distribution. The calculations are considered to be a test of the off-energy-shell effects due to non-local interaction. This calculation is also a test of the approximate distorted waves at 46 MeV and the comparison to the ¹⁴N(p, 2p)¹³C data indicates that the distortion is reasonably well described.     

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.