MTLE Recalls Practice Test

In atomic spectroscopy, you need a light source that emits sharp, element-specific lines—unique wavelengths that identify a particular element. A hollow cathode lamp does exactly this: it uses the element of interest as the cathode, and when a discharge occurs in an inert gas, the excited atoms of that element emit characteristic, narrow emission lines. Those lines serve as precise references for detecting or quantifying the same element in a sample, giving high selectivity and sensitivity for element-specific measurements in both emission and absorption applications. Other lamps provide broad or non-targeted spectra. A tungsten lamp is a continuous spectrum source, not ideal for isolating specific wavelengths. A deuterium lamp is strong in the ultraviolet but isn’t tailored to the spectral lines of a particular element. A mercury lamp offers a limited set of lines, not the customizable, element-focused lines provided by a hollow cathode lamp.