一个类Lehmer问题误差项的均值估计

研究了一个类Lehmer问题的误差项均值估计问题,利用解析方法与Cochrane和的性质给出了它的平均阶估计和一个一次混合均值的渐近公式,所得结果表明该类问题比Lehmer问题更加复杂.     

新型含双酚衍生物三枝氟硼二吡咯染料的合成及其光物理性能

以三聚氯氰为原料合成含醛基的二酚氧基取代中间体（1）; 1分别与酚衍生物（2a~2e）经取代反应制得三酚氧基中间体（3a~3e）; 3a~3e经缩合、氧化和配位等反应合成了5个新型的含双酚衍生物三枝氟硼二吡咯（BODIPY）荧光染料（4a~4e）,其结构经¹H NMR, ¹³C NMR和HR-MS(ESI)表征。4a~4e的最大吸收波长和发射波长分别位于499 nm和508 nm,荧光量子产率为0.41~0.55,显示出BODIPY荧光核典型的光物理性能。     

Temperature dependence of the photothermal laser coolina efficiency for a micro-cantilever

The relationship between the photothermal cooling efficiency of a micro-cantilever＇s mechanical mode and the en- vironmental temperature is studied. The micro-cantilever and a polished fiber end form a low finesse Fabry-Perot （FP） cavity. Experimental results in a temperature range from 77 K to 298 K show that temperature has an obvious influence on photothermal cooling efficiency. The photothermal cooling efficiency, ηph, at 100 K is 10 times that at 298 K. This accords well with the theoretical analysis that the high photothermal cooling efficiency can be achieved when photothermal response time, τph, and mechanical resonant frequency, ω0, are close to the optimal photothermal cooling condition ω0τph = 1. Our study provides an important approach for high effective photothermal cooling and high-sensitivity measurement for force microscopy.     

Temperature dependence of the photothermal laser cooling efficiency for a micro-cantilever

The relationship between the photothermal cooling efficiency of a micro-cantilever’s mechanical mode and the environmental temperature is studied. The micro-cantilever and a polished fiber end form a low finesse Fabry–Perot(FP)cavity. Experimental results in a temperature range from 77 K to 298 K show that temperature has an obvious influence on photothermal cooling efficiency. The photothermal cooling efficiency, ηph, at 100 K is 10 times that at 298 K. This accords well with the theoretical analysis that the high photothermal cooling efficiency can be achieved when photothermal response time, τph, and mechanical resonant frequency, ω0, are close to the optimal photothermal cooling condition ω0τph = 1. Our study provides an important approach for high effective photothermal cooling and high-sensitivity measurement for force microscopy.