In the last part , the differential pas technique , which combines the pas technique with the differential spectrum , overcomes the defect from the two techniques , making it has the both advantage of the pas technique , which is suitable for the measurement of the heavy diffusion > opacity sample , and the advantage of the differential spectrum which is capable of differentiating the overlap spectrum and shoulder peak , is present 第三部分提出導數(shù)光聲光譜技術,將光聲光譜技術和導數(shù)光譜結(jié)合起來,使導數(shù)光聲光譜技術同時具有光聲光譜技術的可適用于強散射,非透明的樣品測量和導數(shù)光譜可分辨重疊光譜,分辨肩峰的優(yōu)點,又克服各自的缺點。