What is a common cause of stray light?

Stray light in spectrophotometric analysis typically refers to light that is not part of the desired measurement spectrum and can interfere with the accuracy of the results. The phenomenon of second-order spectra is a significant contributor to stray light. When a monochromator uses a light source that produces multiple wavelengths, it can produce harmonics (or second-order spectra) that can overlap with the wavelengths of interest. This can result in additional light reaching the detector, which does not belong to the primary spectral band being analyzed and thus leads to inaccuracies in quantification and detection limits.

In this context, dispersion from second-order spectra is a common mechanism by which stray light can occur, causing erroneous readings in spectrophotometry. Addressing this issue often involves using optical filters or correcting the system's calibration to minimize the effects of unwanted wavelengths. The other options, while they might affect overall instrument performance, do not specifically lead to the generation of stray light in the same manner as second-order spectra do.