Drift of amplification factor and its effects in a tri-electrode electron gun†

The drift of the amplification factor p. should induce drifts of the emitted current I a in a fixed-bias circuit and the beam energy in a self-bias circuit.

The μ-drift due to the heat from the filament was measured, and also calculated from the I _A-drift for an hour. The relative μ-drift thus calculated was 1-3% in 10?min in a conventional gun, and it decreased to smaller than 003% in 10?min in an improved gun, where thermal expansion of the Wehnelt electrode was compensated by the movement of the filament supporter. Energy of the beam was 20 kev. The initial emitted current I _A(t= 0) was 198 μA in the conventional gun and 14.4 μA in the improved gun.

The relative energy-drift should be proportional to the relative μ-drift and inversely proportional to (μ+ 1). Accordingly, the relative energy-drift should be 1.3 × 10^?6; in 10?min in the conventional gun, while it should be smaller than 3 ×10^?6 in 10?min in the improved gun, when μ is assumed to be 100 in both guns.     

二芳基乙烯光致变色配合物的研究进展

二芳基乙烯化合物是最有可能实用化的有机光致变色化合物.结合自己的研究方向,从溶液相和晶体相2个方面评述了二芳基乙烯配合物在光致变色性能、无损读取、分子识别/捕获等方面的研究进展.研究表明,在大多数情况下,金属离子参与配位不会阻止配合物的光致变色反应.通过金属离子与二芳基乙烯配体的合理自组装,可以调控配合物的光物理和光化学性质.