水在中红外波段的强吸收有时会遮蔽水溶液中溶质的特征峰,从而干扰溶质的红外谱带归属和分析.提出了一种新方法,控制水峰的吸收强度逐渐变化(强→弱→消失),从而得到高质量的红外光谱.利用单次ATR附件,通过先扫描空ATR晶体N次,经短暂暂停后,再继续扫描载有纯水(或参比溶液)的ATR晶体M次,这样累加得到的背景单光束谱(N+M次扫描)中水的吸收强度就直接与扫描次数N和M相关.选择足够大的扫描次数N和合适的扫描次数M,就可以彻底扣除水峰的干扰.利用该方法,成功获得了K2CO3溶液和牛血清白蛋白(BSA)溶液的消除了水吸收峰的高质量红外光谱.实验结果证实新方法具有快速、高效等优点.文中也讨论了该方法的局限性。

Infrared spectral studies of aqueous solution have been severely limited by the strong water absorption.Usually,it is very difficult to experimentally achieve perfect compensation between the amount of water that contributes to the sample and background spectra.In the present paper,we introduced a new method to make the infrared bands of water disappear during the measurement of an infrared spectrum for aqueous solution.Both background spectrum of the empty ATR cell and that of the water on ATR cell are used in sequence.Qualified infrared spectra of 10% K2CO3 and 10% BSA aqueous solutions were successfully obtained by ATR accessory (single-reflection) without water interference.The experimental results demonstrated that the new method is fast,effective and powerful.The limitation of the new method is also discussed.