红外杂化光谱及其在光谱分离领域的应用

A hybrid spectrum has been introduced to represent the spectrum of the real sample. A hybrid spectrum is obtained by two real spectra through linear combination, the two real spectra are obtained from the same sample but with different pathlengths or concentrations. And then, a series of hybrid spectra can be obtained by simply adjusting the component factor (hybridization coefficient) but no necessary requirement of sample preparation, thus showing different intensities. As the consequence, the spectrum of a real sample with a certain concentration or pathlength can be represented by a desired hybrid spectrum. For the hybrid spectrum applied to practical applications, it is the key to realize the high similarity between the real spectrum and substituted hybrid spectrum. In this project, we will investigate firstly the details of the correlation between the properties (such as sample pathlength, concentration and absorption coefficient) of two real sample spectra used to synthesize the hybrid spectrum and the spectral distortion of the hybrid spectrum; and then control the spectral distortion by experimental factors and error theory; finally achieve a hybrid spectrum with desired intensity and dismissed spectral distortion. Moreover, the method of the hybrid spectrum is superior in spectral background elimination by comparing to some conventional methods. The hybrid spectral method works well not only under the condition of Lambert-Beer law, most importantly, also suitable in the non Lambert-Beer system with strong molecular interactions.

不需制备样品就可获得相应样品的红外单光束谱或吸光率谱是光谱学家梦寐以求的目标。本研究将提出杂化光谱的概念，尝试用杂化光谱替代真实样品的光谱。杂化光谱由同一样品但厚度或浓度不同的两源光谱线性组合构成。改变杂化系数就可以得到不同的杂化光谱，每一杂化谱对应不同的强度，因此，适宜的杂化谱可以代表不同浓度（厚度）的真实样品光谱。控制杂化谱与其代表的真实谱高度类似是杂化谱能否得到实际应用的关键。本项目将研究两源光谱的样品参数（样品厚度，浓度，吸光系数等）与杂化谱失真程度的关系，利用实验参数和误差理论来控制杂化谱的失真程度，期望得到光谱强度可以任意调节但失真程度又可忽略的杂化谱。杂化谱的引入将为扣除背景干扰或光谱分离（样品单光束谱/背景单光束谱的比谱方式，吸光率谱差减方式）提供强有力的新方法。除了适用于满足朗伯比尔定律体系，杂化谱的重要优点是它也适用于存在分子间相互作用的非朗伯比尔复杂体系的背景扣除。

由于分子间相互作用，许多复杂体系不满足朗伯比尔定律。这种情形下，如果已知较低浓度c1的溶液光谱A1，则不能从理论上获得较高浓度c2的溶液光谱A2. 采用两边夹的原理，定义A1谱和A2谱的线性组合为杂化吸光率谱Ah，即Ah=xA1+(1-x）A2，x为杂化系数。改变杂化系数x，杂化谱的强度就会在A1谱和A2谱之间变化，因此可用杂化谱Ah来表达浓度在c1和c2间的任一浓度的溶液光谱。只要得到A1谱和A2谱，不需制备样品，浓度在c1和c2间的真实溶液的光谱都可以用杂化吸光率谱Ah来表达。由于采用了双边夹原理，杂化谱与它代表的真实光谱间的失真程度受到极大抑制，选择合适的A1与A2，杂化谱的失真抑制到可忽略不计的程度。通过引进杂化吸光率谱的概念，将光谱差减技术的应用推广到不满足朗伯比尔定律的体系，获得一种简便、快速、经济和适用范围广的获得高质量红外光谱的新方法。同样原理可定义杂化单光束谱和杂化反射率谱等。.测量时，实现了直接将干扰组分的吸收峰从红外光谱图上彻底扣除的目标。通过引进杂化单光束谱的概念，绕过合适的参比样品难以制备的难题，直接获得强度适宜的杂化参比单光束谱而彻底扣除溶剂或其它干扰组分的吸收峰，从而得到高质量的无其它组分吸收峰干扰的红外光谱。蛋白质水溶液获得了高质量的蛋白质红外光谱。解决了光谱测量时空气中水汽对光谱的干扰问题，水汽吸收峰不出现在最终的光谱图上，可与真空技术获得的光谱媲美，对痕量样品或弱信号体系的红外光谱测量具有重要意义。.NaCl水溶液的红外吸收不满足朗伯比尔定律，根据吸收率杂化谱的性质，利用回归分析，利用不同浓度的氯化钠溶液可以获得失真程度小的光谱，解决了实际工作中样品的光谱测量问题。.根据双边夹原理，创造性地提出了杂化吸光率谱和杂化单光束谱等概念，将杂化谱概念应用到光谱测量领域，扣除杂物光谱干扰，得到高质量的光谱，混合气体，溶液，固体测量时，都得到了令人满意的结果。