UV-Vis spectrophotometer for polymer characterization

一个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分光光度计和时间分辨荧光计等仪器的设计，以分别表征分子如何吸收和发射光。光可以根据其波长来表征，分别对应波长为475 nm、510 nm和650 nm的蓝色、绿色和红色。一个给定仪器用光表征分子的能力是由它的“光谱带宽”或波长分辨率来表征的。光谱带宽越小，对分子的表征越准确。我的实验室目前配备了一台有20年历史的分光光度计，这是我的部门10年前慷慨捐赠的。分光光度计的光谱带宽为2nm。在“过去”，时间分辨荧光计的典型光源是氢灯。氢灯发出的光很弱，因此荧光计的光谱带宽需要加宽，有时高达16纳米，以便获得足够的光进入荧光计。相对便宜、功能强大的时间分辨荧光仪激光源的出现，使荧光测量能够在1纳米的光谱带宽下完成，比我们20年前的分光光度计提供的光谱带宽小。因此，我们用荧光计通过分子发出的光来表征分子的能力现在比我们的分光光度计要好。这种情况是不幸的，因为现代分光光度计可以很容易地实现与1nm一样好的光谱带宽，甚至比1nm好得多。正是出于这个原因，我们要求资金购买更新，更好的分光光度计，其能力将与我们新升级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.