UV-Vis spectrophotometer for polymer characterization

分子如何吸收和发射光提供了该分子的明确特征。这一观察结果导致了仪器的设计，如荧光计和时间分辨荧光计，以表征分子如何吸收和发射光，分别。光可以根据其波长来表征，蓝色、绿色和红色分别对应于475 nm、510 nm和650 nm的波长。给定仪器用光表征分子的能力由其“光谱带宽”或波长分辨率表征。光谱带宽越小，分子的表征就越准确。我的实验室目前配备了一台有20年历史的分光光度计，这是10年前由我的部门慷慨捐赠的。分光光度计的光谱带宽等于2nm。在“旧时代”，时间分辨荧光计的典型光源是氢灯。氢灯发光微弱，因此荧光计的光谱带宽需要加宽，有时高达16 nm，以便获得足够的光进入荧光计。时间分辨荧光计相对便宜、功能强大的激光源的出现使荧光测量能够在1 nm的光谱带宽内完成，比我们20年前的分光光度计所提供的光谱带宽要小。因此，我们通过荧光计发出的光来表征分子的能力现在比我们的分光光度计更好。这种情况是不幸的，因为现代的微波计可以很容易地实现与1 nm一样好的光谱带宽，甚至比1 nm好得多。正是由于这个原因，我们要求资金购买一个更新，更好的分光光度计，其能力将与我们新购买的时间分辨荧光计相当。

How a molecule absorbs and emits light provides an unequivocal signature of that molecule. This observation led to the design of instruments such as spectrophotometers and time-resolved fluorometers to characterizehow molecules absorb and emit light, respectively. Light can be characterized in terms of its wavelength, the blue, green, and red colours corresponding to wavelengths of 475 nm, 510 nm, and 650 nm, respectively. The ability of a given instrument at characterizing a molecule with light is characterized by its "spectral bandwidth" or wavelength resolution. The smaller the spectral bandwidth and the more accurate is the characterization of the molecule. My laboratory is currently equipped with a 20 year-old spectrophotometer which was generouslydonated by my department 10 years ago. The spectral bandwidth of the spectrophotometer equals 2 nm. In the "old days", the typical light source of a time-resolved fluorometer was a hydrogen lamp. The hydrogen lampsemitted weakly so that the spectral bandwidth of the fluorometer needed to be broadened, sometimes up to 16 nm in order to obtain sufficient light into the fluorometer. The advent of relatively cheap, powerful laser sources for time-resolved fluorometers enables fluorescence measurements to be done with a spectral bandwidth of 1 nm, smaller than that afforded by our 20 year-old spectrophotometer. Consequently our ability to characterize molecules by the light they emit with the fluorometer is now better than that of our spectrophotometer. This situation is unfortunate because modern spectrophotometers can easily achieve a spectral bandwidth as good as, and even much better than 1 nm. It is for this reason that we request funds to purchase a newer, better spectrophotometer whose capabilities will be on a par with our newly upgradedtime-resolved fluorometer.