Photoacoustic spectroscopic (PAS) detection of infrared absorption often produces spectra with enhanced intensities for weaker peaks, enabling the detection of features due to overtones and combinations, as well as less-abundant isotopic species. To illustrate this phenomenon, we present and discuss PAS infrared spectra of calcite (CaCO₃). We use linearization of rapid-scan spectra, as well as comparing step-scan and rapid-scan spectra, to demonstrate that saturation is not the driving force behind these enhanced intensities. Our results point to a new knowledge gap, since a theoretical basis for the enhancement of these weak bands has not yet been developed.

光声光谱（PAS）对红外吸收的检测通常会产生强度增强的光谱（用于弱峰），从而能够检测由于泛音和组合以及同位素含量较低而引起的特征。为了说明这种现象，我们介绍并讨论了方解石（CaCO <sub> 3 </ sub>）的PAS红外光谱。我们使用快速扫描光谱的线性化，以及比较步进扫描和快速扫描光谱，以证明饱和度不是这些增强强度的驱动力。我们的结果指出了新的知识鸿沟，因为尚未开发出增强这些弱带的理论基础。