Suppression of frequency-mixing effect for pm-level heterodyne interferometers based on "zero coupling" optical path length control.

Optical path length (OPL) noise resulting from stray light significantly constrains interferometry displacement measurements in the low-frequency band. This paper presents an analytical model considering the presence of stray light in heterodyne laser interferometers. Due to the cyclic nonlinear coupling effect, there will be some special OPLs of stray light, minimizing the frequency-mixing impact to zero. Consequently, we propose a noise suppression scheme that locks the OPL of stray light at the zero coupling point. Therefore, we significantly enhanced the interference displacement measurement noise within the low-frequency band. Experimental results show that the interferometer achieves a displacement noise level lower than 6 pm/Hz1/2 covering 1 mHz.

In situ assembly of nickel-based ultrathin catalyst film for water oxidation.

A nickel-based ultrathin catalyst film is assembled in situ from a solution of Ni(OAc)2 and a Schiff-base ligand L. The resulting ultrathin catalyst film shows a low overpotential of 330 mV, a steady current of 7 mA cm-2 for water oxidation over 10 h.

One-Pot Synthesis of 3-Substituted 4H-Quinolizin-4-ones via Alkyne Substrate Control Strategy.

Three-substituted 4H-quinolizin-4-ones were obtained via a facile method with good selectivity and high efficiency. On the basis of alkyne substrate control, the mild and cost-efficient reaction has a broad substrate scope (20 examples, up to 93% yield) and is also easy to scale up. Active sites on the products allow for further modifications. The alkyne substrate control strategy could be further extended to achieve more complex three-substituted 4H-quinolizin-4-one skeletons.