The Beer-Lambert law is a core spectroscopic relationship widely used across the undergraduate chemistry curriculum and beyond. The derivation of this model is a common topic for upper-level chemistry courses. But, due to its abstract nature, this derivation can often seem like a mathematical exercise detached from the molecular origins of…

In this undergraduate physical chemistry laboratory experiment, students acquire a high-resolution infrared absorption spectrum of carbon dioxide and use their data to show that the rotational-vibrational state populations follow a Boltzmann distribution. Data are acquired with a mid-infrared laser source and infrared detector. Appropriate…