参比样品的吸收强度与红外光谱反常吸收

Absorbance of Infrared Bands of the Background Sample and Anomalous Absorption

红外光谱测量时,参比样品尽量选用IR透明材料或IR弱吸收材料,比如KBr窗片、CS2溶剂等。测溶液的红外光谱时,为扣除溶剂的影响,常选用溶剂作参比样品。如果溶剂有强的IR吸收峰,溶液IR谱上则会出现反常吸收现象。本文探讨了反常吸收峰与参比样品吸收强度的关系,提出了制备参比样品的原则和避免反常吸收而获得高质量红外光谱的注意事项,对复杂物质的红外光谱测量具有指导意义。

In the present paper,an absorbance spectrum was obtained by scanning the same sample(polystyrene film)both in background and sample single-beam measurements.It was found that a series of residual spikes appear in the strong absorption regions.The residuals are significant different from that of random noise.There should be a nearly straight line according to theory analysis while spikes appear.Therefore those spikes are called anomalous absorption.The experimental results indicate that anomalous absorption is related to the absorbance of infrared bands of the background sample.If the absorbance of an infrared band is lower than 1.0,anomalous absorption can be suppressed thoroughly.The reasons for anomalous absorption were discussed and how to prevent the appearance of anomalous absorption by selecting appropriate background samples were suggested.